Essay // Biological & Developmental Psychology: Frontal Lobes, Impulsiveness in Children & Jean Piaget’s Theory

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(Photo: Jez C Self / Frontal Lobe Gone)

Part 1 of 3 | Frontal Lobes (& Frontal Lobe Damage)

 

The Wisconsin Card Sorting Test (WCST; Grant & Berg, 1948; Heaton, Chelune,Talley, & Curtis, 1993) has long been used in Neuropsychology and is among the most frequently administered neuropsychological instruments (Butler, Retzlaff, & Vanderploeg, 1991).

The test was specifically devised to assess executive functions mediated by the frontal lobes such as problem solving, strategic planning, use of environmental instructions to shift procedures, and the inhibition of impulsivity. Some neuropsychologists however, have questioned whether the test can measure complex cognitive processes believed to be mediated by the Frontal lobes (Bigler, 1988; Costa, 1988).

The WCST test, until this day remains widely used in clinical settings as frontal lobe injuries are common worldwide. Performance on the WCST test is believed to be particular sensitive in reflecting the possibilities of patients having frontal lobe damage (Eling, Derckx, & Maes, 2008). On each Wisconsin card, patterns composed of either one, two, three or four identical symbols are printed. Symbols are either stars, triangle, crosses or circles; and are either red, blue, yellow or green.

At the start of the test, the patient has to deal with four stimulus cards that are different from one another in the colour, form and number of symbols they display. The aim of the participant would be to correctly sort cards from a deck into piles in front of the stimulus cards. However, the participant is not aware whether to sort by form, colour or by number. The participant generally starts guessing and is told after each card has been sorted whether it was correct or incorrect.

Firstly they are generally instructed to sort by colour; however as soon as several correct responses are registered, the sorting rule is changed to either shape or number without any notice, besides the fact that responses based on colour suddenly become incorrect. As the process continues, the sorting principle is changed as the participant learns a new sorting principle.

potbIt has been noted that those with frontal lobe area damage often continue to sort according to only one particular sorting principle for 100 or more trials even after the principle has been deemed as incorrect (Demakis, 2003). The ability to correctly remember new instructions with for effective behaviour is near impossible for those with brain damage: a problem known as ‘perseveration’.

Another widely used test is the ‘Stroop Task’ which sets out to test a patient’s ability to respond to colours of the ink of words displayed with alternating instructions. Frontal patients are known for badly performing to new instructions. As the central executive is part of the frontal lobe, other problems such as catatonia – a condition where patients remain motionless and speechless for hours while unable to initiate – can arise. Distractibility has also been observed, where sufferers are easily distracted by external or internal stimuli. Lhermite (1983) also observed the ‘Utilisation Syndrome’ in some patients with Dysexecutive Syndrome (Normal & Shallice, 1986), who would grab and use random objects available to them pathologically.

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Part 2 of 3 | Impulsiveness in Children

 

Image: PsyBlog

The Frontal lobe, responsible for most executive functions and attention, has shown to take years [at least 20] to fully develop. The Frontal lobe [located behind the forehead] is responsible for all thoughts and voluntary behaviour such as motor skills, emotions, problem-solving and speech.

In childhood, as the frontal lobe develops, new functions are constantly added; the brain’s activity in childhood is so intense that it uses nearly half of the calories consumed by the child in its development.

As the Pre-Frontal Lobe/Cortex is believed to take a considerable amount of at least 20 years to reach maturity (Diamond, 2002), children’s impulsiveness seem to be linked to neurological factors with the Pre-Frontal Lobe/Cortex; particularly, their [sometimes] inability to inhibit response(s).

The idea was supported by developmental psychologist and philosopher Jean Piaget‘s  Theory of Cognitive Development of Children [known for his epistemological studies] where he showed the A-not-B error [also known as the “stage 4 error” or “perseverative error”] is mostly made by infants during the substage 4 of their sensorimotor stage.

Researchers used 2 boxes, marked A and B, where the experimenter had repeatedly hid a visually attractive toy under the Box A within the infant’s reach [for the latter to find]. After the infant had been conditioned to look under Box A, the critical trial had the experimenter move the toy under Box B.

Children of 10 months or younger make the « perseveration error » [looked under Box A although fully seeing experimenter move the toy under Box B]; demonstrating a lack of schema of object permanence [unlike adults with fully developed Frontal lobes].

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Frontal lobe development in adults was compared with that in adolescents, e.g. Sowell et al (1999); Giedd et all (1999); who noted differences in Grey matter volume; and differences in White matter connections. Adolescents are likely to have their response inhibition and executive attention performing less intensely than adults’. There has also been a growing & ongoing interest in researching the adolescent brain; where great differences in some areas are being discovered.

The Pre-Frontal Lobe/Cortex [located behind the forehead] is essential for ‘mentalising’ complex social and cognitive tasks. Wang et al (2006) and Blakemore et al (2007) provided more evidence between the difference in Pre-Frontal Lobe activity when ‘mentalising’ between adolescents and adults. Anderson, Damasio et al (1999) also noted that patients with very early damage to their frontal lobes suffered throughout their adult lives.

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2 subjects with Frontal Lobe damage were studied:

1) Subject A: Female patient of 20 years old who suffered damages to her Frontal lobe at 15 months old was observed as being disruptive through adult life; also lied, stole, was verbally and physically abusive to others; had no career plans and was unable to remain in employment.

2) Subject B was a male of 23 years of age who had sustained damages to his Frontal lobe at 3 months of age; he turned out to be unmotivated, flat with bursts of anger, slacked in front of the television while comfort eating, and ended up obese in poor hygiene and could not maintain employment. [However…]

Reflexion

While research and tests have proven the link between personality traits & mental abilities and frontal brain damage, the physiological defects of the frontal lobe would likely be linked to certain traits deemed negative by a subject willing to be a functional member of society [generally Western societies].

However, personality traits similar to the above Subjects [A & B] may in fact not always be linked to deficiency and/or damage to the frontal lobes; as many other factors are to be considered when assessing the behaviour & personality traits of subjects; where [for example] violence and short temper may [at times] be linked to a range of factors and environmental events during development, or other mental strains such as sustained stress, emotional deficiencies due to abnormal brain neurochemistry, genetics, or other factors that may lead to intense emotional reactivity [such as provocation or certain themes/topics that have high emotional salience to particular subjects, ‘passion‘]

 

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Part 3 of 3 | Jean Piaget’s Theory of Cognitive Development (0 – 12 yrs)

Jean Piaget’s theory developed out of his early interest in observing animals in their natural environment. Piaget published his first article at the age of 10 about the description of an albino sparrow that he had observed in the park, and before the age of 18, journals had accepted several of his papers about molluscs. During his adolescent years, the young theorist developed a keen interest in philosophy, particularly “epistemology” [the branch of philosophy focused on knowledge and the acquisition of it]. However, his undergraduate studies were in the field of biology and his doctoral dissertation was once again, on molluscs.

For a short while, Piaget then worked at Bleuler’s psychiatric clinic where his interest in psychoanalysis grew. As a results, he moved to France and attended the Sorbonne university, in 1919 to study clinical psychology and also pursued his interest in philosophy. In Paris, he worked in the Binet Laboratory with Theodore Simon on the standardisation of intelligence tests. Piaget’s task was to monitor children’s correct response to test times, but instead, he became much more interested in the mistakes that children made, and developed the idea that the study of children’s errors could provide an insight into their cognitive processes.

Piaget came to realise that through the process and discipline of psychology, he had an opportunity to create links between epistemology and biology. Through the integration of the disciplines of psychology, biology and epistemology, Piaget aimed to develop a scientific approach to the understanding of knowledge – the nature of knowledge and the ways in which an organism acquires knowledge. As a man who valued richness and detail, Piaget was not at all impressed by the reductionist quantitative methods used by the empiricists of the time, however, he was influenced by the work on developmental psychology by Binet, a French psychologist who had pioneered studies of children’s thinking [his method of observing children in their natural setting was one that Piaget followed himself when he left the Binet laboratory].

Piaget later integrated his own experience of psychiatric work in Bleuler’s clinic with the observational and questioning strategies that he had learned from Binet. Out of this fusion of techniques emerged the “Clinical Interview” [an open-ended, conversational technique for eliciting children’s thinking (cognitive) processes]. It was the child’s own subjective judgement and explanation that was of interest to Piaget, as he was not testing a particular hypothesis, but rather looking for an explanation of how the child comes to understand his or her world. The method is not simple, and the team of Piaget’s researchers had to be trained for 1 year before they actually started collecting data. They were trained and educated about the “art” of asking the right questions and testing the truth of what the children said.

Piaget’s career was devoted to the quest for the mechanisms guiding biological adaptation, and also the analysis of logical thought [that derives from these adaptations and interaction with the exterior environment] (Boden, 1979). He wrote more than 50 books and hundreds of articles, correcting many of his earlier ideas in later life. At its core, the theory of Jean Piaget is concerned with the human need to discover and acquire deeper understanding and knowledge.

Piaget’s incredible output of concepts and ideas characterises his attitude towards constant construction and reconstruction of his theoretical system, which was quite consistent with his philosophy of knowledge, and perhaps indirectly to the school of thought of the mind as an “active” entity.

This section will explore the model of cognitive structure developed by Piaget along with the modifications and some of the re-interpretations that subsequent Piagetian researchers have made to the master’s initial ideas. Although many details have been questioned, it is undeniable that Piaget’s contribution to the understanding of thinking processes [cognitive] of both children and adults.

One great argument made by the theorist suggested that if we are to understand how children think we ought to look at the qualitative development of their problem-solving abilities.

Two famous examples from Piaget’s experiments will be considered that explore the thinking processes in children, showing how they develop more sophisticated problem-solving skills.

Example 1 – One of Piaget’s dialogue with a 7-year-old

Adult:    Does the moon move or not?
Child:    When we go, it goes.
Adult:    What makes it move?
Child:    We do.
Adult:    How?
Child:    When we walk. It goes by itself.

(Piaget, 1929, pp. 146-7)

From this example and other observations based on the similar theme, Piaget described a particular period in childhood which is marked by egocentrism. Since the moon appears to move with the child, she concluded that it does indeed do so. But as the child grows and her sense of logic follows, there is a shift from her own egocentric perspective where the child starts to learn to differentiate between what she sees and she “knows”. Gruber and Vonèche (1977) provide a good example of how an older child used her sense of logic to investigate the movement of the moon. This particular child had sent his younger brother for a walk down the garden while he himself remained immobile. The younger child reported that the moon moved with him, but the older boy realised from his observation that the moon did not move and could then disprove this wrong information with his brother.

Example 2 – Estimating the Quantity of a Liquid

FA Piaget Liquid Quantity

FIGURE A. Estimating a quantity of liquid

This example is taken from Piaget’s research into children’s understanding of quantity. Let us assume that John [aged 4] and Mary [aged 7] are given a problem; two glasses, A and B, are of equal capacity [volume] but glass A is short and wide and glass B is tall and narrow [See Figure A]. Glass A is filled to a particular height and the children would then be asked, separately, to pour liquid into glass B [tall and narrow] so that it would contain the same amount as glass A. Despite the striking proportional differences of the 2 containers, John could not grasp that the smaller diameter of glass B requires a higher level of liquid. To Mary, John’s response is incredibly senseless and stupid: of course one would have to add more to glass B. Piaget interestingly saw the depth of the argument that was in the responses of those children. John could not “see” that the liquid in A and the liquid in B are not equal, because his thought processes are using a mechanism that is qualitatively different in terms of reasoning and that is not yet developed [perhaps due to physiological/hardware limitations] and lacks the mental operations that would have allowed him to solve the problem. Mary, the 7 year old girl finds it hard to understand 4 year old John’s stupidity and why he could not perceive his error.

Facing this situation, Piaget brilliantly proposed that the essence of knowledge is “activity” – a line of thought and perspective adopted by many psychologists and intellectuals from the German and French school of Lacan quite opposite to the early British thoughts that assumed the mind to be “passive” and mostly shaped by the effects of the outside environment.  This argument is not only one that embraces human ingenuity and creativity and acknowledges our instinctual drives to thrive and succeed but also characterises the mind as an entity with high creative power instead of simple junction of neurons conditioned to react to stimuli from its environment almost helplessly as the “passive” school assumed it to be. Hence, to Piaget and ourselves, the essence of knowledge is “activity”, he could be referring to the infant directly manipulating objects and in doing so also learning about their properties. It may also refer to a child pouring liquid from one glass to another to find out which has more in it. Or it may refer to the adolescent forming hypotheses to solve a scientific dilemma. In the examples mentioned, it is important to note that the learning process of the child is taking place through “action”, whether physical (e.g. exploring a ball of clay) or mental (e.g. thinking of various outcomes and reflecting on what they mean). Piaget’s emphasis on activity was important in stimulating the child-centred approach to education, because he firmly believed that for lasting learning to occur, children would not only have to manipulate objects but also manipulate and define ideas. The major educational implications of Piaget will be discussed later in this section.

 

Assumptions of Piaget’s Theory of Development: Structure & Organisation

Through his carefully devised techniques, and using observations, dialogues and small-scale experiments, Piaget suggested that children progress through a series of stages in their thinking, each of which synchronises with major changes in the structure or logic of their intelligence. [See Table A]

TA Piaget - Stages of Intellectual Development

TABLE A. The Stages of Intellectual Development in Piaget’s Theory

Piaget named the main stages of development and the order in which the occurred as:

I. The Sensori-Motor Stage [0 – 2 years]
II. The Pre-Operational Stage [2 – 7 years]
III. The Concrete Operational Stage [7 – 12 years]
IV. The Formal Operational Stages [12 years but may vary from one child to the other]

Piaget’s structures are sets of mental operations, which can be applied to objects, beliefs, ideas or anything in the child’s world, and these mental operations are known as “schemas”. The schemas are characterised as being evolving structures, in other words, structures that grow and change from one stage to the next.

The details of each section of the 4 stages will be explored below, however it is fundamental that we first understand Piaget’s concept of the unchanging or “invariant” [to use his own term – this may be related to temperament but here it involves another set of abilities] aspects of thought, which refers to the broad characteristics of intelligent activity that remains constant throughout the human organism’s life.

These are the organisation of schemas and their adaptation through assimilation and accommodation.

Organisation: Piaget used this term to explain the innate ability to coordinate existing cognitive structures, or schemas, and combine them into more complex systems [e.g. a baby of 3 months old has gained the ability to combine looking and grasping, with the earlier reflex of sucking]. The baby is able to perform all three actions together when feeding from her mother’s breast or a feeding bottle, an ability that the new born child did not originally have in his/her repertoire. A further example would be Ben who at the age of 2 had learned to climb downstairs while carrying objects without dropping them, and also to open doors. This means that he could then combine all three operations to deliver newspaper to his grandmother in the basement flat. To note, each separate operation combines into a new action more complex than the sum of the parts.

The complexity of the organisation also grows as the schemas become more elaborate. Piaget described the development of a particular action schema in his son Laurent as he attempted to strike a hanging object. Initially, Laurent only made random movement towards the object, but at the age of 6 months the movements had evolved and were now deliberate, focused and well directed. As Piaget put it in his description, at 6 months old, Laurent possessed the mental structure that guided the action involved in hitting a toy. Laurent had also gained the ability to accommodate his actions to the weight, size and shape of the toy and its distance from him.

The next invariant function, adaptation is characterised by the striving of the organism for balance [or equilibrium] with the environment, and is achieved through the further processes of “assimilation” and “accommodation”. During the process of assimilation, the child’s repertoire of knowledge expands and he/she takes in [learns about] a new experience [and the knowledge acquired with it] and fits it into an existing schema. For example, a child may learn the words “dog” and “car”, and following this enigmatic event, the child may call all animals “dogs” [i.e. different animals taken into a schema related to the child’s understanding of dog], or all vehicles with four wheels are called “cars”. The process of accommodation balances this erroneous process, where the child adjusts an existing schema to fit in with the nature of the environment [i.e. from experience, the child begins to perceive that cats can be distinguished from dogs, and may develop schemas for these 2 different animals – also that cars can be distinguished from other vehicles such as trucks or lorries.

By these two processes, namely assimilation and accommodation, the child achieves a new state of equilibrium which is however not permanent as this balance is generally soon upset as the child assimilates further new experiences or accommodates her existing schemas to another new idea.

Equilibrium only seems to prepare the child for more disequilibrium through further learning and adaptation; these two processes occur together and cannot be thought of separately. Assimilation provides the child with consolidation for mental structures; and accommodation results in growth and change. All adaptations contains the components of both processes and striving for balance between assimilation and accommodation [Remember: Organisation  Adaptation + (Assimilation & Accommodation)] leads to the child’s intrinsic motivation to learn [This is also reminiscent of the psychodynamic school of thought as several processes colliding to find balance in its model of the mental life of the individual mind]. When new experiences are within the child’s response range in terms of abilities, then conditions are said to be at their best for change and growth to occur.


The Stages of Cognitive Development

To adepts of Piaget’s outlook, intellectual development is a continuous process of assimilation and accommodation. We will not describe the four stages identified in the development of cognition from birth to about 12 years old [in normal children]. This order is similar for all children but the age these milestones are achieved may vary from one child to another – with the stages being:

I. The Sensori-Motor Stage [0 – 2 years]
II. The Pre-Operational Stage [2 – 7 years]
III. The Concrete Operational Stage [7 – 12 years]
IV. The Formal Operational Stages [12 years but may vary from one child to the other]


I. The Sensori-Motor Stage (about 0 – 2 years) | Stage 1 of 4

During the sensori-motor stage the child changes from a newborn, who focuses almost entirely on immediate sensory and motor experiences, to a toddler who possesses a rudimentary capacity for thinking. Piaget described in detail the process by which this occurs, by documenting his own children’s behaviour. On the basis of such observations, carried over the first 2 years of life, Piaget divided the sensori-motor stage into 6 sub-stages. [See Table B]

TB Sub-stages of the sensori-motor period

TABLE B. Substages of the sensori-motor period according to Piaget

The first substage, reflex activity, included the reflexive behaviours and spontaneous rhythmic activity with which the infant is born. Piaget called the second substage primary circular reactions. He used the term “circular” to emphasise how children tend to repeat an activity, especially those that are pleasing or satisfying (e.g. thumb sucking). The term “primary” refers to simple behaviours that are derived from the reflexes of the first period [e.g. thumb sucking develops as the thumb is assimilated into a schema based on the innate suckling reflex].

Secondary circular reactions refer to the child’s willingness to repeat actions, but the word “secondary” is used here to point out the behaviours that are the child’s very own. In other words, she is not limited to just repeating actions based on early reflexes, but having initiated new actions, she can now repeat these if they are satisfying. However, at the same time, these actions tend to be directed outside the child (unlike simple actions like thumb sucking) and are aimed at influencing the environment around her.

This is Piaget’s description of his own daughter Jacqueline at 5 months old, kicking her legs (in itself a primary circular reaction) in what gradually ascends to a secondary circular reaction as the leg movement is repeated not just for itself, but is initiated in the presence of a doll.

Jacqueline looks at a doll attached to a string which is stretched from the hood to the handle of the cradle. The doll is approximately the same level as the child’s feet. Jacqueline moves her feet and finally strikes the doll, whose movement she immediately notices… The activity of the feet grows increasingly regular whereas Jacqueline’s eyes are fixed on the doll. Moreover, when I remove the doll Jacqueline occupies herself quite differently; when I replace it, after a moment, she immediately starts to move her legs again.

(Piaget, 1936, p. 182)

In displaying such behaviours, Jacqueline seemed to have established a general relation between her movement and the doll’s, and was also engaged in a secondary circular reaction.

Coordination of Secondary Circular Reactions, being substage 4 of the Sensori-motor period, and as the word “coordination” implies, it is particularly at this substage that children begin to combine different behavioural schema. In the following extracted section, Piaget described how his daughter (aged 8 months) combined several schemas, such as “sucking an object” and “grasping an object” in a series of coordinated actions when playing with a new object:

Jacqueline grasps an unfamiliar cigarette case which I present to her. At first she examines it very attentively, turns it over, then holds it in both hands while making the sound apff (a kind of hiss which she usually makes in the presence of people). After than she rubs it against the wicker of her cradle then draws herself up while looking at it, then swings it above her and finally puts it in her mouth.

(Piaget, 1936, p. 284)

Jacqueline’s behaviour illustrates how a new object is assimilated to various existing schema in the fourth substage. In the following stage, that of tertiary circular reactions children’s behaviours become more flexible and when they repeat actions they may do so with variations, which can lead to new results. By repeating actions with variations, children are, in effect, accommodating established schema to new contexts and needs.

The final sub-stage of the sensori-motor period is known as the substage of Internal Representations and it refers to the child’s achievement of mental representation. The previous substages the child has interacted with the world through her physical motor schema, another way of phrasing it would be that, she has acted directly on the world. In this final substage, she can now act “indirectly” on the world because she has developed the capacity to hold mental representations of the world – that is, she can now think and plan.

As evidence for children attaining the level of mental representation, Piaget pointed out that by this substage children have a full concept of object permanence. Piaget noticed that very young infants ignored even highly attractive objects once they were out of sight [e.g. a child reaching for a toy, but then the toy is suddenly covered with a cloth and it immediately leads to the child losing all interest in it and would not attempt to search for it, and might even just look away]. According to Piaget it was only after the later substages that children demonstrated an awareness [by searching and trying to retrieve the object] that the object was “permanently” present even if it was temporarily out of sight. Searching for an object that cannot be seen directly implies that the child has a memory of the object, i.e. a mental representation of it.

It is only towards the end of the sensori-motor period that children demonstrated novel patterns of behaviour in response to a problem. For example, if a child wants to reach for a toy and comes across an object between herself and the desired toy, younger children might just try and reach for the toy directly and it is possible that the child knocks over the object while reaching for the target toy – this is best described as “Trial and Error” performance. In the later substages, the child might solve the problem by instead first removing the object out of the way before reaching for the desired toy. Such structured behaviour suggests that the child was able to plan ahead, which indicates that he/she had a mental representation of what she was going to do.

An example of planned behaviour by Jacqueline was given where she was trying to solve the problem of opening a door while carrying two blades of grass at the same time:

She stretches out her right hand towards the knob but sees that she is cannot turn it without letting go of the grass. She puts the grass on the floor, opens the door, picks up the grass again and enters. But when she wants to leave the room things become complicated. She put the grass on the floor and grasps the door knob but then she realises that in pulling the door towards her she will simultaneously chase away the grass which she placed between the door and the threshold. She therefore picks it up in order to put it outside of the door’s zone of movement.

(Piaget, 1936, pp. 376-7)

Jacqueline solved the problem of the grass and the door before she opened the door. It is assumed that she would have had a mental representation of the problem, which permitted her to work out the solution, before she acted.

A third line of evidence for mental representations comes from Piaget’s observation of deferred imitation, that is when children carry out a behaviour that is a reflection of copied behaviour that was previously taken in by the developing child. Piaget provides a good example of this:

At 16 months old Jacqueline had a visit from a little boy of 18 months who she used to see from time to time, and who, in the course of the afternoon got into a terrible temper. He screamed and he tried to get out of a playpen and pushed it backward, stamping his feet. Jacqueline stood observing him in amazement, having never witnessed such a scene before. The following day, she herself screamed in her playpen and tried to move it, stamping her foot lightly several times in succession.

(Piaget, 1951, p. 63)

This suggests that if the little boy’s behaviour was repeated by Jacqueline a day later, she would have had to have retained an image of his behaviour, i.e. she had a mental representation of what she had seen from the day before, and that representation provided the basis for her own copy of the temper tantrum.

To conclude, during the sensori-motor period, the child advances from very simple and limited reflex behaviours at birth, to complex behaviours at the end of the period. The more complex behaviours depend on the progressive combination and elaboration of the schema, but are, at the beginning, limited to direct interactions with the world – thus, the name Piaget gave to this period because he thought of the child developing through her sensori-motor interaction with the environment. It is only towards the end of that period that the child is not limited to immediate interaction anymore because she has now developed the ability to mentally represent her world [mental representation], and with this ability the child can manipulate her mental images (or symbols) of her world, in other words, she can now act on her thoughts about the world as well as on the world itself.

 

Revisions of the Sensori-motor Stage

Jean Piaget’s observations of babies during this first stage lasting until 2 years of age, have been largely confirmed by subsequent reseachers, however Piaget may have underestimated children’s mental capacity to organize the sensory and motor information they take in. Several investigators have shown that children have abilities and concepts earlier than Piaget thought.

Bower (1982) examined Piaget’s hypothesis that young children did not have an appreciation of objects if they were not in sight. For this experiment, children a few months old were recruited and shown an object, and shortly after a screen was moved across in front of the object [so that it would be hidden/unseen from the child’s visual field], to then finally be moved back to its original position. This scenario was presented with 2 slight changes: in Condition 1 the object was still in place and hence seen again by the child when the screen was moved back to its original location; and in Condition 2, the object was removed so the child would perceive the object to have disappeared when the screen was moved back. After monitoring the children’s heart rate to measure changes [which reflect surprise]. To go back to Piaget’s assumptions from his qualitative observations, it would be assumed that children of a few months old do not retain information about objects that are no longer present, and if this was the case, we would not register any heart rate change because as there should be no element of surprise [i.e. the child would not expect an object to be there once the screen was moved back to its original location], thus in Condition 2, no reaction should be displayed by the children, however it was found that children displayed more surprise in Condition 2 and Bower inferred that the children would have had an expectation of the object to still be in its position or “re-appear” after the screen was moved back – this would be the evidence that young children must retain a mental representation of the object in their mind [could be interpreted as young children having some basic form of object permanence even if not properly developed at an earlier age than the assumptions of Piaget based on the results of his experimental methods].

In a further experiment, Baillargeon and DeVos (1991) showed 3-month-old children objects that moved behind a screen and then re-appeared from the other side of the screen. The upper half of the screen had a window and in one condition the children saw a short object move behind the screen [the object was small and below the level of the window and hence when it passed behind the screen it was completely out of sight / not visible, until it appeared at the other side of the screen].

In a second condition a taller object was passed behind the screen, and it was high enough to be seen through the window as it passed from one side to the other. Furthermore, Baillargeon and DeVos created an “impossible event” by passing the tall object through the screen without it appearing through the window, and it lead to the children displaying more interest by looking longer at the scenario than that with the small object. This lead to the argument that children reacted so, due to their expectation of the taller object to appear through the window, and hence this would suggest that young children early in the sensori-motor stage have an awareness of the continued existence of objects even when they are out of view. These results along with that of Bower (1982) seem to suggest that young children to have “some” understanding of object permanence earlier than assumed.

Another one of Piaget’s conclusion was also investigated further by another group of researchers who wanted to find out if children only developed planned action [which demonstrated their ability to form mental representations] at the end of the sensori-motor stage. Willatts (1989) placed an attractive toy on a cloth, out of the reach of 9-month-old children; the children could pull the cloth to access the attractive toy. However, the children could not reach the cloth directly since it was not accessible as Willatts placed a light barrier between the child and the cloth [the child had to move the barrier to reach the cloth]. The experiment showed that children were able to access the toy by carrying out appropriate the series of actions [i.e. first moving the barrier, then pulling the cloth to bring the toy within reach]. Most importantly, many of the children carried out the correct actions within the first occasion of being presented with the problem without the need of going through a “trial and error” phase. Willatts argued that for such young children to demonstrate novel planned actions, it may be inferred from such behaviour that they are operating on a mental representation of the world which they can make use of to organise their behaviour before carrying it out [This is also earlier than assumed by Piaget’s experiments].

Another point made by Piaget was that deferred imitation was an evidence that children should have a memory representation of what they had seen earlier. Soon after birth however it was found that babies are able to imitate the facial expression of an adult or the head movement (Meltzoff and Moore, 1983, 1989), however such imitation is performed in the presence of the stimulus being imitated. From Piaget’s experiments, it was initially deduced that stored representations are only achieved by children towards the end of the sensori-motor stage, however, Meltzoff and Moore (1994) showed that 6-week old infants could imitate a behaviour a day after they had seen the original behaviour. In Meltzoff and Moore’s study some children saw an adult make a facial gesture [e.g. sticking out her tongue] and others just saw the adult’s face while she maintained a neutral expression. The next day, all the children in the experiment saw the same adult, however this time, she kept a passive face. Compared to the children who had not seen any gesture, the children who had seen the tongue protrusion gesture the day before were more likely to make tongue protrusions to the adult the second time they saw her. Meltzoff and Moore argued that for the children to be able to perform those actions they would have had to have a mental representation of the action at a much earlier age than Piaget’s experiments concluded

 

II. The Pre-operational Stage (about 2 – 7 years) | Stage 2 of 4

This stage will be divided in 2 periods: (a) The Pre-conceptual Period (2 – 4 years) and (b) the Intuitive Period (4 – 7 years)


(a) The Pre-Conceptual Period (2 – 4 years)

The pre-conceptual period builds on the ability for internal, or symbolic thought to develop based on the latest advancements during the final stages of the sensori-motor period. During the pre-conceptual period [2 – 4 years old], we can observe a rapid increase in children’s language which, in Piaget’s view, results from the development of symbolic thought. Piaget unlike other theorists of language [who suggested that thought emerges from linguistic competence] argued that thought arises out of action and this idea is supported by research into cognitive abilities of deaf children who, despite limitations in language, have the abilities for reasoning and problem solving. Piaget argued that thought shapes language far more than language shapes thought [at least during the pre-conceptual period], and symbolic thought is also expressed in imaginative play.

However there are some limitations in the child’s abilities at the pre-conceptual period (2-4 years) of the pre-operational stage. The pre-operational child is still centred in her own perspective and finds it difficult to understand that other people can look at things differently. Piaget called this the “self-centred” view of the world and used the term egocentrism.

Egocentric thinking occurs due to the child’s belief that the universe is centred on herself, and thus finds it hard to “decentre”, that is, to take the perspective of another individual. The dialogue below gives an example of a 3-year-old’s difficulty in taking the perspective of another person:

Adult: Have you any brothers or sisters?
John: Yes, a brother.
Adult: What is his name?
John: Sammy.
Adult: Does Sammy have a brother?
John: No.

It is quite clear here that 3-year old John’s inability to decentre makes it hard for the child to realise that from Sammy’s perspective, he himself is a brother.

The egocentric trait at this particular period of development is apparent in their flawed perspective taking tasks. One of the most famous experiments carried out by Piaget is the three mountains experiment tasks, and it involves exploring children’s ability to see things from the perspective of another. In 1956, Piaget and Inhelder asked children between the ages of four and twelve [4 – 12 years old] to say how a doll would perceive an array of three mountains from different perspectives [i.e. by placing the doll at different locations].

FJ Piaget III Mountain Task.jpg

FIGURE J. Model of the mountain range used by Piaget and Inhelder viewed from 4 different sides

 

For example in Figure J, a child might be asked to sit at position A, and a doll would be placed at one of the other positions (B, C or D), then the child would be made to choose from a set of different views of the model, the view that the doll could see. When four and five year old children [4 and 5 years old] were asked to do this task, they often chose the view that they themselves could see (rather than the doll’s view) and it was not until 8 or 9 years of age that children could confidently work out the doll’s view. Piaget argued that this should be convincing in asserting that young children were still learning to manage their egocentricity and could not decentre from their own perspective to work out the perspective / view of the doll.

However, several criticisms have been made regarding the 3 mountain tasks, and one researcher, Donaldson (1978) pointed out that the tasks were unusual to use with young children who might not have a good familiarity with model mountains or be used to working out other people’s views of landscapes. Borke (1975) carried out a similar task to Piaget, but instead of using model mountains, he used the layout of toys that young children typically spend time with in play. She also altered the way that children were asked to respond to the question about what a different person’s view would be, and found that children as young as 3 or 4 years of age had some basic understanding of how another person’s perspective would be different from another position. This was much earlier than previously deduced from Piaget’s experiments, and shows that the type of objects and procedures used in a task can have a huge impact on the performance of the children. By using mountains, Piaget may have selected a far too complex content for such young children’s perspective-taking abilities to be demonstrated optimally.


Borke’s Experiment: Piaget’s Mountains Revised & Changes in the Egocentric Landscape

Borke’s main inquisition was about the appropriateness of Piaget’s three mountain tasks for such young children, and was concerned with the aspects of the task that were not related to perspective-taking and whether this might have adversely affected the children’s performance. These aspects were:

(i) the mountain from a different angle or not may not have sparked any interest or motivation in the children
(ii) the pictures of the doll’s views that Piaget had asked the children to select may have been too taxing for their intelligence
(iii) due to the task being unusual in nature, children may have performed poorly because they were unfamiliar with such a task

Borke considered if some initial practice and familiarity with the task would improve the children’s performance, and with those points in mind, Borke repeated the basic design of Piaget and Inhelder’s experiment but changed the content of the task, avoided the use of pictures and gave children some initial practice. She also used 4 three-dimensional  displays: there were a practice display and three experimental displays [see FIGURE B].

FB Borke's 4 three-dimensional displays

FIGURE B. A schematic view of Borke’s four three-dimensional displays viewed from above.

 

Borke’s participants were 8 three-year-old children and 14 four-year-old children attending a day nursery. Grover, a character from the popular children’s television show, “Sesame Street” was used for the experiment as a substitute for Piaget’s doll. There we 2 identical versions of each display (A and B), and Display A was for Grover and the child to look at, and Display B was on a turntable next to the child.

The children were tested individually and were first shown a practice display which consisted of a large toy fire engine. Borke placed Grover at one of the sides of the practice Display A so that Grover could view the fire engine from a point of view [perspective] that was different from the child’s own view of this display.

A duplicate of the fire engine [practice Display B] appeared on a revolving turntable, and Borke briefed the children, explaining that the table could be turned so that the child could look at the fire engine from ANY side. Children were then prompted to turn the table until their view of the Display B matched the exact perspective that Grover had while looking at Display A. If necessary, Borke even helped the children to move the turntable to the correct position or walked the children round Display A to show them the exact view [perspective] that Grover had in view

Once the practice session was over, the child was ready to take part in the experiment itself. This time, the procedures were similar, except no help was provided by the experimenter. Every single child was shown three dimensional displays, one at a time [see FIGURE B].

Display 1 included a toy house, lake and animals
Display 2 was based in Piaget’s model of three mountains
Display 3 included several scenes with figures and animals
Note: There were 2 identical copies of each display, and of course, children had to rotate the second  copy which was on a turntable to match the perspective [view] that Grover had in sight [as prepared in the practice session].

What Borke found was that most of the children in the experiment were able to work out Grover’s perspective for Display 1 [three and four-year-olds were correct in 80% of trials] and for Display 3 [three-year-olds were correct in 79% of trials and four-year-olds, in 93% of trials. However, for Display 2 [Piaget’s mountains], the three-year-olds were correct in only 42% of trials and four-year-olds in 67% of trials. Borke calculated an analysis of variance, and found that the difference between Displays 1 & 3 and Display 2 was significant at p < 0.001. As for errors, there were no significant differences in the children’s responses for any of the 3 positions – 31% of errors were egocentric [i.e. child rotated Display B to show their OWN view/perspective of Display A, rather than Grover’s view].

Borke successfully demonstrated that the task had a major influence on the perspective-taking performances of young children. When the display included toys that the children were familiar with and hence recognisable, and when the response involved rotating a turntable to work out Grover’s perspective, even the comparatively complex Display 3 task was successfully achieved by the children.

This seems to suggest that the poor performance by the children in Piaget’s original experiment involving three mountains was due in part to the unfamiliar nature of the objects that the children were shown.

Borke concluded that the potential for understanding the viewpoint of another was already present in children as young as 3 and 4 years of age, and this seems to be a reliable addition and revision to Piaget’s original assumption that children of this age are egocentric and incapable to taking the viewpoint of others. It now seems clear that although their perspective taking abilities may not be fully developed, they tend to make egocentric responses when they misunderstood the task, but when given the appropriate conditions, they show that they are capable of working out another’s viewpoint.

However, on a final note, it is important to also consider that Borke’s finding that children as young as three years can perform correctly in perspective-taking tasks stands in firm contrast to other researchers who have found that three-year-olds have difficulty realising another person’s perspective when the child and the other person are both looking at the same picture from different point of view [e.g. at the Louvres museum] (e.g., Masangkay et al, 1974).

 

(a) The Pre-Conceptual Period (2 – 4 years)… continued from above

Piaget use the three mountains task to investigate visual perspective taking and it was on the basis of this task that he concluded that young children were egocentric. There are also a variety of other perspective taking scenarios, and these include the ability to empathise with other people’s emotions, and the ability to know what other people are or may be thinking depending on the scene, setting and scenario (Wimmer and Perner, 1983). In other words, young children are less egocentric than Piaget initially assumed.

 

(b) The Intuitive Period (4 – 7 years)

At about the age of four, there is a further shift in thinking where the child begins to develop the mental operation of ordering, classifying and quantifying in a more systematic way. The term “intuitive” was particularly chosen by Piaget because the child is largely unaware of the principles that underlie the operations she completes and cannot explain why she has done them, nor can she carry them out in a fully satisfactory way, although she is able to carry out such operations involving ordering, classifying and quantifying.

Difficulties can be observed if a pre-operational child is asked to arrange sticks in a particular order. 10 sticks of different sizes from A (the shortest) to J (the longest), arranged randomly on a table were given to the children. The child was asked to arrange them in ascending order [order of length]. Some pre-operational children could not complete the task at all. Some other children arrange a few sticks correctly, but could not complete the task properly. And some put all the smaller ones in one and all the longer one in another. A more advance response was to arrange the sticks so that tops of the sticks when order even though the bottoms were not [See FIGURE C].

FC Pre-operational ordering different-sized sticks

FIGURE C. The pre-operational child’s ordering of different-sized sticks. An arrangement in which the child has solved the problem of seriation by ignoring the length of the sticks.

To sum up, the pre-operational child is not capable of arranging more than a very few objects in the appropriate order.

It was also discovered that pre-operational children also have difficulty with class inclusion tasks – those that involve part-whole relations. Let us assume that a child is given a box that contains 18 brown beads and 2 white beads; all the beads are wooden. When asked “Are there more brown beads than wooden beads?” [note that the question does not make sense since all the beads are made of wood but some are brown and some are white], the pre-operational child tends to say that there are “more brown beads”. The child at the intuitive-period of the pre-operational stage finds it hard to consider the class of “all beads” [wooden] and at the same time considering the subset of beads, the class of “brown beads”[wooden + brown].

This findings is generally true for all children in the pre-operational stage, irrespective of their cultural background. Investigators further found that Thai and Malaysian children gave responses that were very similar to those of Swiss children at this stage of life [4 – 7 years old] and in the same sequence od development [the intuitive period].

Here, a Thai boy who was shown a bunch of 7 roses and 2 lotus [all are in the class of flowers], states that there are more roses than flowers [problem with class of all flowers] when prompted by the standard Piagetian questions:

Child: More roses.
Experimenter: More than what?
Child: More than flowers.
Experimenter: What are the flowers?
Child: Roses.
Experimenter: Are there any others?
Child: There are.
Experimenter: What?
Child: Lotus
Experimenter: So in this bunch which is more roses or flowers?
Child: More roses.

(Ginsburg and Opper, 1979, pp. 130-1)

One of the most extensively investigated aspects of the pre-operational child’s thinking processes is what Piaget called “conservation”. Conservation refers to the understanding that superficial changes in the appearance of a quantity do not mean that there has been any real change in the quantity. For example, if we had 10 dolls placed in line, and then they were re-arranged in a circle, it would not mean that the quantity has been altered [i.e. if nothing is added or subtracted from a quantity then it remains the same – conservation].

Piaget’s experiments revealed that children in the pre-operational stage generally find it hard to grasp the concept that an object’s qualities remain intact even if it is changed in shape and appearance. A series of conservation tasks were used in the investigations and examples are given in FIGURE D and PLATE A.

FD Piaget - Tests de Conservation

FIGURE D. Some tests of conservation: (a) two tests of conservation of number (rows of sweets and coins; and flowers in vases); (b) conservation of mass (two balls of clay); (c) conservation of quantity (liquid in glasses). In each case illustration A shows the material when the child is first asked if the two items or sets of items are the same and illustration B shows the way that one item or set of items is transformed before the child is asked a second time if they are still similar.

PA Piaget - Conservation of Number

PLATE A. A 4-year-old puzzles over Piaget’s conservation of number experiments; he says that the rows are equal in number in arrangement (a), but not in arrangement (b) « because they’re all bunched together here ».

If 2 perfectly identical balls of clay are given to a child and if questioned about whether the quantity of clay being similar in both balls, the child will generally agree that it is. However, if one of the balls of clay is rolled and shaped into a sausage [see FIGURE D(b)], and the child is questioned again about whether the amount are similar, he/she is more likely to say that one is larger than the other. When asked about the reasons for the answer, they are generally unable to give an explanation, but simply say “because it is larger”.

Piaget suggested that a child has difficulty in a task such as this because she could only focus on one attribute at a time [e.g. if length is being focussed on, then she may think that the sausage shaped clay, being longer, has more clay it it. According to Piaget, for a child to appreciate that the sausage of clay has the same amount of clay as the ball would require an understanding that the greater length of the sausage is compensated for by the smaller cross section of the sausage. Piaget said that pre-operational children cannot apply principles such as compensation.

A further example to demonstrate this weakness in the child’s reasoning about conservation is through the sweets task [see FIGURE D(a)]. In this scenario, a child is shown 2 rows of sweets with a similar number of sweets in each row [presented with one to one layout] and when asked if the numbers match in each row, she will usually agree. Shortly after, one row of sweets is made longer by spreading them out, and the child is once again asked whether the number of sweets in similar in each row; the pre-operational child usually makes a choice between the rows suggesting that one has more sweets in it. He/she may for example think that the longer row means more objects [logic of the pre-operational child]. At this stage, the child does not realise that the greater length of the row of sweets is compensated for by the greater distance between the sweets.

Compensation is only one of several processes that can help children overcome changes in appearance; another process is known as “reversibility”. This is where the children could think of literally “reversing” the change; for example if the children imagine the sausage of clay being rolled back and reshaped into a ball of clay, or the row of sweets being pushed back together, they may realise that once the change has been reversed the quantity of an object or the number of items in the row remains similar to before. Pre-operational children lack the thought processes needed to apply principles like “compensation” and “reversibility”, and therefore they have difficulty in conservation tasks.

In the next stage, which is the third stage of development known as the “Concrete Operational Stage”, children will have achieved the necessary logical thought processes that give them the ability to use the required principles and handle conservation techniques and other problem-solving tasks easily.

 

Revisions of the Pre-Operational Stage

While Piaget claimed that the pre-operational child cannot cope with tasks like part-whole relations or conservations, because they lack the logical thought processes to apply principles like compensation. Other researchers have pointed out that children’s lack of success in some tasks may be due to factors other than ones associated with logical processes.

The pre-operational child seems to lack the ability to grasp the concept of the relationship between the whole and the part in class inclusion tasks, and will happily state that there are more brown beads than wooden beads in a box of brown and white wooden beads “because there are only two white ones”. Some other researchers have focussed their attention on the questions that children are asked during such studies and found them to be unusual [e.g. it is not often in every day conversation that we ask questions such as “Are there more brown beads or more wooden beads?”]

Minor variations in the wording of the questions that enhances and clarifies meaning can have positive effects on the child’s performance. McGarrigle (quoted Donaldson, 1978) showed children 4 toy cows, 3 black and 1 white, all were lying asleep on their sides. If the children were asked “Are there more black cows or more cows?” [as in a standard Piagetian experiment with a meaningless trap wording of the question] they tended not to answer correctly. McGarrigle found that in a group of children aged 6 years old, 25% answered the standard Piagetian question correctly, and when it was rephrased, 48% of the children answered correctly – a significant increase. From such an observation it was deduced that some of the difficulty of the task was in the wording of the question rather than just an inability to understand part-whole relations.

Donaldson (1978) put forward a different reason from Piaget as a cause for children’s poor performance in conservation tasks, he argued that children have a build in model of the world by formulating hypotheses that help them anticipate future events based on their past experiences. Hence, in the case of the child there is an expectation about any situation, and his/her interpretation of the words she hears will be influenced by the expectations she brings to the situation. When in a conservation experiment, for example, the experimenter asks a child if there are the same number of sweets in two rows [FIGURE D(a)]. Then one of the rows is changed by the experimenter while emphasising that it is being altered. Donaldson suggested that it is quite fair to assume that a child may be compelled to deduce that there would be a link between the change that occurred [the display change] and the following question [about the number of sweets in each row]; otherwise why would such a precise question come from an adult if there had not been any change? If the child is of the belief that adults only carry actions when they desire a change, then he/she might assume that a change has occurred.

McGarrigle and Donaldson (1974) explored this idea in an experiment with a character known as “Naughty Teddy”, and it was this character rather than the experimenter who changed the display layout and the modification was explained to the children as an “accident” [in such a context the child might have less expectation that a deliberate treatment had been applied to the objects, and there would be no reason to believe a change had taken place]. This procedure was setup in such a way because McGarrigle and Donaldson found that children were more likely to give the correct answer [that the objects remained the same after being messed up by Naughty Teddy] in this new context than in the classical Piagetian context.

Piaget was correct to point out the problems that pre-operational children face with conservation and other reasoning tasks. However, other researchers since Piaget have found out that, given the appropriate wording and context, young children seem capable of demonstrating at least some of the abilities that Piaget thought only developed later [even if these abilities are not well developed at such a stage].

Piaget also found that pre-operational children had difficulties when faced with tasks requiring “transitive inferences”. In this case, the children were showed 2 rods, A and B. Rod A was longer than Rod B, and then Rod A was taken out of sight of the children, who were then showed only Rod B and Rod C [B was longer than C]. When the children were then asked which rod was longer, Rod A or Rod C? Young children on the pre-operational stage find such questions hard and Piaget provided the explanation that these children cannot make logical inferences such as: if A is longer than B and B is longer than C, then A must be longer than C.

Bryant and Trabasso (1971) also considered transitive inference tasks and wondered whether children’s difficulties had more to do with remembering all the specific information about the objects rather than making an inference [i.e. for children to respond correctly they would not only have to make an inference but also remember the lengths of all the rods they had seen]. Bryant and Trabasso proposed that it was possible that young children [with brains still growing and developing physiologically] who have limited working memory capacity, were unable to retain in memory all the information they needed for the task.

In another scenario, children were faced with the similar task in an investigation of transitive inferences, however this time they were trained to remember the lengths of the rods [they were trained on the comparisons they needed to remember, i.e., that A was longer than B, and B was longer than C]. It is only when Bryant and Trabasson were satisfied that the children could remember all the information were they asked the test question [i.e. which rod was longer? A or C?]. The experimenters found that children could now answer correctly. So, the difficulty that Piaget noted in those tasks was more to do with forgetting some of the information needed to make the necessary comparisons, rather than a failure in making logical inferences.

 

III. The Concrete Operational Stage (about 7 – 12 years) | Stage 3 of 4

At the age of about 7 years old, the thinking processes of children change once again as they develop a new set of strategies which Piaget called “concrete operations”. These strategies are considered concrete because children can only apply them to immediately present objects. However, thinking becomes much more flexible during the concrete operational period because children lose their tendency to simply focus on one aspect of the problem, rather now, they are able to consider different aspects of a task at the same time. They now have processes like compensation and reversibility [as explained earlier in understanding volume], and they now succeed on conservation tasks. For example, when a round ball of clay is transformed into a sausage shape, children in the concrete operational stage will say, “It’s longer but it’s thinner” or “If you change it back, it will be the same.”

Conservation of number is achieved first [about 5 or 6 years], then this is followed by the conservation of weight [around 7 or 8], and the conservation of volume is fully understood at about 10 or 11 years old. Operations like addition and subtraction, multiplication and division become easier at this stage. Another major shift comes with the concrete operational child’s ability to classify and order, and to understand the principle of class inclusion. The ability to consider different aspects of a situation at the same time enables a child to perform successfully in perspective taking tasks [e.g. in the three mountains task of Piaget, a child can consider that she has one view of the model and that someone else may have a different view].

However, there are still some limitations on thinking, because children are reliant on the immediate environment and have difficulty with abstract ideas. Take the following question: “Edith is fairer than Susan. Edith is darker than Lily. Who is the darkest and who is the fairest?” Such a problem is quite difficult for concrete operational children who may not be able to answer it correctly. However, if children instead are given a set of dolls representing Susan, Edith and Lily, they are able to answer the question quickly. Hence, when the task is made a “concrete” one, in this case with physical representations, children can deal with the problem, but when it is presented verbally, as an abstract task, children have difficulty. Abstract reasoning is not found within the repertoire of the child’s skills until the latter has reached the stage of formal operations.

 

Revisions of the Concrete Operational Stage

A great amount of Piaget’s observations and conclusions about the concrete operational stage have been broadly confirmed by subsequent research. Tomlinson-Keasey (1978) found that conservation of number, weight and volume are acquired in the order stated by Piaget.

As in the previous stage, the performance of children in the concrete operational period may be influenced by the context of the task. In some context, children in concrete operational period may display more advanced reasoning that would typically be expected of children in that stage. Jahoda (1983) showed that 9-year-olds in Harare, Zimbabwe, had more advanced understanding of economic principles than British 9-year-olds. The Harare children, who were involved in the small business of their parents, had strong motivation to understand the principles of profit and loss. Jahoda set up a mock shop and played a shopping game with the children. The British 9-year-olds could not provide any explanation about the functioning of the shop, did not understand that a shopkeeper buys for less than he sells, and did not know that some of the profit has to be set aside for the purchase of new goods. The Harare children, by contrast, had mastered the concept of profit and could understand trading strategies. These principles had been grasped by the children as a direct outcome of their own active participation in running a business. Jahoda’s experiment, like Donaldson’s studies (1978), indicated the important function of context in the cognitive development of children.

 

IV. The Formal Operational Stage (12 years old) | Stage 4 of 4

During the third period of development, the Concrete operations stage, we have seen that the child is able to reason in terms of objects [e.g., classes of objects, relations between objects) when the objects are present. Piaget argued that only during the period of Formal Operations that young people are able to reason hypothetically, now they no longer depend on the “concrete” existence of objects in the real world, instead they now reason with verbally stated hypotheses to consider logical relations among several possibilities or to deduce conclusions from abstract statements [e.g. consider the syllogistic statement, “all blue birds have two hearts”; “I have a blue bird at home called Adornia”; “How many hearts does Adornia have?” The young person who has now reached formal operational thinking will give the correct answer by abstract logic, which is: “Two hearts!” Children within the previous stage will generally not get past complaining about the absurdity of the scenario.

Young people are now also better at solving problems by considering all possible solutions systematically. If requested to formulate as many combinations of grammatically correct words from the letters A, C, E, N, E, V, A, a young person at the formal operational stage could first consider all combination of letters AC, AE, AN, etc., verifying if such combinations are words, and then going on to consider all three letter combinations, and so on. In the earlier stages, children would attend to such tasks in a disorganised and unsystematic fashion.

Inhelder and Piaget (1958) explained the process of logical reasoning used by young people when presented with a number of natural science experiments. An example of one of their task, “The Pendulum Task” can be seen in Figure E.

FE Piaget - Pendulum Prob

FIGURE E. The pendulum problem. The child is given a pendulum, different lengths of string, and different weights. She is asked to use these to work out what determines the speed of the swing of the pendulum (from Inhelder and Piaget, 1958).

 

The young person as the participant here is given a string [that can be shortened or lengthened], and a set of weights, and then asked to figure out what determines the speed of the swing of the pendulum. The possible factors are the length of the string, the weight at the end of the string, the height of the release point and the force of the push. In this particular scenario the solutions to the solving the problem are all in front of the participant, however the successful reasoning involves formal operations that would also have to incorporate a systematic consideration of various possibilities, the formulation of hypotheses (e.g., “What could happen if I tried a heavier weight?”) and logical deductions from the results of trials with different combinations of materials.

The other tasks investigated by Inhelder and Piaget (1958) included determining the flexibility of metal rods, balancing different weights around a fulcrum, and predicting chemical reactions. These tasks mimic the steps required for scientific inquiry, and Piaget argued that formal scientific reasoning is one of the most important characteristic of formal operational thinking. From his original work, carried out in schools in Geneva, Piaget claimed that formal operational thinking was a characteristic stage that children or young people reached between the ages of 11 and 15 years – having previously gone through the earlier stages of development.

 

Revision of the Formal Operational Stage

Piaget’s claim has been rectified by recent research, more researchers have found that the achievement of formal operational thinking is more gradual and haphazard than Piaget assumed – it may be dependent on the nature of the task and is often limited to certain domains.

FF Piaget - Proportion of boys at different Piagetian stg

FIGURE F. Proportion of boys at different Piagetian stages as assessed by three tasks (from Shayer and Wylam, 1978).

Shayer et al. (1976; Shayer and Wylam 1978) gave problems such as the pendulum task [FIGURE E] to school children in the UK. Their results [see FIGURE F] showed that by 16 years of age only about 30% of young people had achieved “early formal operations” [Is this shocking compared to French speaking Europe where Piaget implemented his theory? Could this provide a partial explanation to the lack of personality, emotion, creativity, openness, depth and sophistication in some populations? Interesting questions…]. Martorano (1977) gave ten of Piaget’s formal operational tasks to girls and young woman aged 12 – 18 years in the USA. At 18 years of age success on the different tasks varied from 15% to 95%; but only 2 children out of 20 succeeded on all ten tasks. Young people’s success on one or two tasks might indicate some formal operational reasoning, but their failure on other tasks demonstrated that such reasoning might be limited to certain tasks or contexts. It is highly likely that young people only manage to achieve and apply formal reasoning across a range of problem tasks much later during their adolescence.

Formal thinking has been shown by some researchers as an ability that can be achieved through training, FIGURE G shows the results of such a study by Danner and Day (1977), where they mentored students aged 10 years, 13 years and 17 years in 3 formal operational tasks. As expected, training had a limited effect on the 10-year-olds, but it had marked effects at 17 years old. In summary, it seems that the period from 11 – 15 years signals the beginning of the potential for formal operational thought, rather than its achievement. Formal operational thought may only be used some of the time, in the domains we are generally familiar with, are trained in, or which have a great significance to us – in most cases formal thinking is not used. After all, we tend to know areas of life where we should have thought things out logically, but in retrospect realise we did not do so [without any regrets sometimes].

FG Piaget - LvL of availability of formal thought

FIGURE G. Levels of availability of formal thought. Percentage of adolescents showing formal thought, with and without coaching (from Danner and Day, 1977).

The Educational Implications of Jean Piaget’s Theory of Cognitive Development

Piaget’s theory was planned and developed over many decades throughout his long life, and at first, it was slow to make any productive impact in the UK and the USA, but from the 1950s its ambitious, embracing framework for understanding cognitive growth was becoming the accepted and dominant paradigm in cognitive development.

Whatever the shortcomings are with Piaget’s theory, it impossible to deny his ingenious contributions, as his approach provided the most comprehensive description of cognitive growth ever put forward on earth. It has had considerable impact in the domains of education, most notably for child-centred learning methods in nursery and infant schools, for mathematics curricula in the primary school, and for science curricula at the secondary school level.

Piaget argued that young children’s thinking processes are quite different from that of an adult, and they also view he world from a qualitatively different perspective. It goes with the logic that a teacher must make a firm effort to adapt to the child and never assume that what may be appropriate for adults should necessarily be right for the child. The idea of “active learning” is what lies at the heart of this child-centre approach to education. From the Piagetian perspective, children learn better from actions rather than from passive observations [e.g., telling a child about the properties of a particular material is less effective than creating an environment in which the child is free to explore, touch, manipulate and experiment with different materials. A good teacher should recognise that each child needs to construct knowledge for him or herself, and active learning results in deeper understanding.

 

JeanPiaget

« Our real problem is: what is the goal of education? Are we forming children who are only capable of learning what is already known? Or should we try to develop creative and innovative minds capable of discovery from the preschool age through life? » – Jean Piaget (1896 – 1980)

So, how can a teacher promote active learning on the part of the pupil? First, it should be the child rather than the teacher who initiates the activity. This should not lead us to allow the child a complete freedom to do anything they want to do, but rather a teacher should set tasks which are finely adjusted to the needs of their pupils and which, as a result, are intrinsically motivating to young learners. For example, nursery school classrooms can provide children with play materials that encourage their learning; set of toys that encourage the practice of sorting, grading and counting; play areas, like the Wendy House, where children can develop role-taking skills through imaginative and explorative play; and materials like water, sand, bricks and crayons that help children make their own constructions and create symbolic representations of the objects and people in their lives. From this range of experiences, the child develops knowledge and understanding for herself, and a good teacher’s role is to create the conditions in which learning may best take place, since the aim of education is to encourage the child to ask questions, try out experiments and speculate, rather than accept information and routine conventions unthinkingly – this also allows the child to learn and be creative about her subjective experience which is unique and different to any other child.

(1919) Jaroslava &amp; Jiri by Alphonse Mucha (1860 - 1939)

(1919) Jaroslava & Jiri, The Artist’s Children by Alphonse Mucha (1860 – 1939)

Secondly, a teacher should be concerned with the process rather that the end-product. This is in line with the belief that a teacher should be interested in the reasoning behind the answer that a child gives to a question rather than just in the correct answer. Conversely, mistakes should not be penalised, but treated as responses that can give a teacher insights into the child’s thinking processes at that time.

The whole idea of active learning resulted in changed attitudes towards education in all its domains. A teacher’s role is not to impart information, because in Piaget’s view, knowledge is not something to transmitted from an expert master teacher to an inexpert pupil. It should be the child, according to Piaget, who sets the pace, where the teacher’s role is to create situations that challenge the child [creatively] to ask questions, to form hypotheses and to discover new concepts. A teacher is the guide in the child’s process of discovery, and the curriculum should be adapted to each child’s individual needs and intellectual level.

In mathematics and science lessons at primary school, children are helped to make the transition from pre-operational thinking to concrete operations through carefully arranged sequences of experiences which develop an understanding for example of class inclusion, conservation and perspective-taking. At a later period, a teacher can also encourage practical and experimental work before moving on to abstract deductive reasoning. Through this process, a teacher can provide the conditions that are appropriate for the transition from concrete operational thinking to the stage of formal operations.

The post-Piagetian research into formal operational thought also has strong implications for teaching, especially science teaching in secondary schools. The tasks that are used in teaching can be analysed for the logical abilities that are required to fulfil them, and the tasks can then be adjusted to the age and expected abilities of the children who will attempt them.

Considering the wide range of activities and interests that appear in any class of children, learning should be individualised, so that tasks are appropriate to individual children’s level of understanding. Piaget did not ignore the importance of social interaction in the process of learning, he recognised the social value of interaction and viewed it as an important factor in cognitive growth. Piaget pointed out that through interaction with peers, a child can move out of the egocentric viewpoint. This generally occurs through cooperation with others, arguments and discussions. By listening to the opinion of others, having one’s own view challenged and experiencing through others’ reactions the illogicality of certain concepts, a child can learn about perspectives other than her own [egocentric]. Communication of ideas to others also helps a child to sharpen concepts by finding the appropriate words.

SigmundFreudYouthAge

 

« Everyone knows that Piaget was the most important figure the field has ever known… [he] transformed the field of developmental psychology. »

(Flavell, 1996, p.200)

« Once psychologists looked at development through Piaget’s eyes, they never saw children in quite the same way. »

(Miller, 1993, p.81)

« A towering figure internationally. »

(Bliss, 2010, p.446)

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References

  1. Anderson, S.W., Bechara, A., Damasio, H., Tranel, D., Damasio, A.R. (1999) Impairment of social and moral behaviour related to early damage in human prefrontal cortex. Nat Neurisci, 2(11), 1032-7
  2. Baillargeon, R and DeVos, J. (1991). Object permanence in young infants: further evidence. Child Development, 62, 1227-46.
  3. Blakemore, S.J., Den Ouden, H., Choudhury, S., Frith, C. (2007). Adolescent development of the neural circuitry for thinking about intentions. Social Cognitive and Affective Neuroscience, 2(2), 130-9
  4. Bliss, J. (2010). Recollections of Jean Piaget. The Psychologist, 23, 444-446.
  5. Boden, M. A. (1979). London: Fontana.
  6. Borke, H. (1975). Piaget’s mountains revisited: Changes in the egocentric landscape. Developmental Psychology, 11, 240-3.
  7. Bower, T.G.R. (1982). Development in Infancy, 2nd San Francisco: W. H. Freeman
  8. Bryant, P. E. and Trabasso, T. (1971). Transitive inferences and memory in young children. Nature, 232, 456-8.
  9. Butler, M., Retzlaff, P., & Vanderploeg, R. (1991). Neuropsychological test usage. Professional Psychology: Research and Practice, 22, 510-512
  10. Danner, F. W. and Day, M. C. (1977). Eliciting normal operations. Child Development, 48, 1600-6.
  11. Demakis, G. J. (2003). A meta-analytic review of the sensitivity of the Wisconsin Card Sorting Test to frontal and lateralized frontal brain damage. Neuropsychology, 17, 255-264
  12. Diamond A. (2002). Normal development of prefrontal cortex from birth to young adulthood: cognitive functions, anatomy, and biochemistry. In: Stuss DT, Knight RT, editors. Principles of frontal lobe function. New York: Oxford University Press. P 466-503
  13. Donaldson, M. (1978). Children’s Minds. London: Fontana.
  14. Eling, P., Derckx, K., & Maes, R. (2008). On the historical and conceptual background of the Wisconsin Card Sorting Test. Brain and Cognition, 67, 247-253
  15. Flavell, J.H. (1996). Piaget’s legacy. Psychological Science, 7, 200-203.
  16. Giedd, J.N., Blumenthal, J., Jeffries, N.O., Castellanos, F.X., Liu, H., Zijdenbos, A., et al. (1999). Brain development during childhood and adolescence: a longitudinal MRI study. Nat Neurosci, 2, 861-863
  17. Ginsburg, H. and Opper, S. (1979). Piaget’s theory of intellectual development: An introduction. Englewood Cliffs, NJ: Prentice-Hall.
  18. Grant, D.A. and Berg, E.A. (1948). A Behavioural Analysis of Degree Impairment and Ease of Shifting to New Responses in Weigh-Type Card Sorting Problem. Journal of Experimental Psychology, 39, 404-411
  19. Gruber, H. & Vonèche, J.J. (1977). The Essential Piaget. London: Routledge & Kegan Paul.
  20. Heaton, R.K., Chelune, G.J., Talley, J.L., Kay, G.G., & Curtis, G. (1993). Wisconsin Card Sorting Test manual: Revised and expanded. Odessa, FL: Psychological Assessment Resources
  21. Inhelder, B. and Piaget, J. (1958). The growth of logical thinking from Childhood to Adolescence. London: Routledge & Kegan Paul.
  22. Jahoda, G. (1983). European ‘lag’ in the development of an economic concept: a study in Zimbabwe. British Journal of Developmental Psychology, 1, 113-20.
  23. Lhermitte, F. (1983) “Utilization Behaviour” and its relation to lesions of the frontal lobes. Brain, 106, 237-255
  24. Martorano, S. C. (1977). A developmental analysis of performance on Piaget’s formal operations tasks. Developmental Psychology, 13, 666-72.
  25. Masangkay, Z.S., McCluskey, K.A., McIntyre, C. W., Sims-Knight, J., Vaughn, B. E. and Flavell, J.H. (1974). The early development of inferences about the visual percepts of others. Child Development, 45, 237-46.
  26. McGarrigle, J. and Donaldson, M. (1974). Conservation accidents. Cognition, 3, 341-50.
  27. Meltzoff, A and Moore, M. (1983). Newborn infants imitate adult facial gestures. Child Development, 54, 702-9.
  28. Meltzoff, A.N and Moore, M. K. (1989). Imitation in newborn infants: exploring the range of gestures imitated and the underlying mechanisms. Development Psychology, 25, 954-62.
  29. Miller, P.H. (1993). Theories of Developmental Psychology (3rd edn). Englewood Cliffs, NJ: Prentice-Hall.
  30. Miller P, Wang XJ (2006) Inhibitory control by an integral feedback signal in prefrontal cortex: A model of discrimination between sequential stimuli. Proc Natl Acad Sci USA, 103(1), 201-206
  31. Norman, D.A., & Shallice, T. (1986). Attention to action: Willed and automatic control of behaviour. (Center for Human Information Processing Technical Report No. 99, rev. ed.) In R.J. Davidson, G.E. Schartz, & D. Shapiro (Eds.), Consciousness and self-regulation: Advances in research, (pp. 1-18). New York: Plenum Press
  32. Piaget, J and Inhelder, B. (1956). The Child’s Conception of Space. London: Routledge & Kegan Paul.
  33. Piaget, J. (1929). The Child’s Conception of the World. New York: Harcourt Brace Jovanovich.
  34. Piaget, J. (1936/1952). The Origin of Intelligence in the Child. London: Routledge & Kegan Paul.
  35. Piaget, J. (1951). Play, Dreams and Imitation in Childhood. London: Routledge & Kegan Paul.
  36. Shayer, M. and Wylam, H. (1978). The distribution of Piagetian stages of thinking in British middle and secondary school children: II. British Journal of Educational Psychology, 48, 62-70.
  37. Shayer, M., Kuchemann, D.E. and Wylam, H. (1976). The distribution of Piagetian stages of thinking in British middle and secondary school children. British Journal of Educational Psychology, 46, 164-73.
  38. Smith, P., Cowie, H. and Blades, M. (2003). Understanding children’s development. 4th ed. pp.388-416.
  39. Sowell ER, Thompson PM, Holmes C.J., Jernigan, T.L., Toga A.W. (1999). In vivo evidence for post-adolescent brain maturation in frontal and striatal regions. Nat Neurosci, 2, 859-861
  40. Willatts, P. (1989). Development of problem solving in infancy. In A. Slater and G. Bremner (eds), Infant Development. Hillsdale, NJ: Lawrence Erlbaum
  41. Wimmer, H. and Perner, J. (1983). Beliefs about beliefs: representations and constraining function of wrong beliefs in young children’s understanding of deception. Cognition, 13, 103-28.

Actualisé: 12 Juillet 2018 | Danny J. D’Purb | DPURB.com

____________________________________________________

While the aim of the community at dpurb.com has  been & will always be to focus on a modern & progressive culture, human progress, scientific research, philosophical advancement & a future in harmony with our natural environment; the tireless efforts in researching & providing our valued audience the latest & finest information in various fields unfortunately takes its toll on our very human admins, who along with the time sacrificed & the pleasure of contributing in advancing our world through sensitive discussions & progressive ideas, have to deal with the stresses that test even the toughest of minds. Your valued support would ensure our work remains at its standards and remind our admins that their efforts are appreciated while also allowing you to take pride in our journey towards an enlightened human civilization. Your support would benefit a cause that focuses on mankind, current & future generations.

Thank you once again for your time.

Please feel free to support us by considering a donation.

Sincerely,

The Team @ dpurb.com

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Essay // Biopsychology: How our Neurons work

neuron-cell-complete-diag

(Image: WPClipArt)

As vast as our universe is, so are its complexities. One of the most complex of objects in it remains the human brain, an organ which when fully grown requires 750 millilitres of oxygenated blood every minute to maintain normal activity – of the total amount of oxygen delivered to the body’s tissues by the arteries, 20 % is consumed by the brain which only makes up 2% of the body’s weight. It also has 100 billion neurons with each connected to 7000 others, leading to a surprising 700 trillion connections. This complexity is far from excessive as we study the importance of the construction of the brain for civilisation and all life on our planet. This fascinating organ is not only at the basis of low-level biological tasks such as heart rate monitoring, respiration and feeding, but it is also vital in the evolution of our behaviours for survival (e.g. perceiving, learning and making rapid decisions). At the heart of human existence, it is also the organ allowing the human organism to explore higher abilities unique to its kind such as thoughts, emotions, consciousness and love.

While nearly 50% of the Central Nervous System and Peripheral Nervous System are neurons, they are supported by glial cells. The ratio of Neurons to glial cells in the human brain is close to 1:1 (Azevedo et al., 2009) and glial cells come in 3 important types:

Firstly, astrocytes [also known as ‘star cell’] produce chemicals needed for neurons to function such as extracellular fluid, provide nourishment [linked to blood vessel] and clean up dead neurons. They also help keep the neuron in place.

Secondly, oligodendrocytes support the axon by creating a myelin coating which increases the speed and efficiency of axonal conduction [in the PNS myelin is produced by Schwann cells].

Thirdly and lastly, microglia works with the immune system by protecting the brain from infections while also being responsible for inflammation in cases of brain damage.

Neurons are cells that are devised to ensure the reception, conduction, and transmission of electrochemical signals and come in several types depending on their structure and function. The 3 main types are Multipolar, Bipolar and Unipolar neurons.

MBU

Most neurons in the brain are multipolar, and these have many extensions from their body: one axon and several dendrites. Bipolar neurons have two extensions: one consisting of dendrites and one of axon and are typically specialised sensory pathways (e.g. vision, smell, sight and hearing).  Unipolar neurons are cells with a single extension (an axon) from their body and are mostly somatosensory (e.g. touch, pain, temperature, etc). Although existing in variety, all neurons perform the same overall function: to process and transmit information.

The neuron is composed of three main parts, firstly the cell body [also known as the ‘soma’] is a primary component of the neuron that integrates the inputs received by the neurons to the axon hillock. The body or soma is between 5 and 100 microns in diameter (a micron is one-thousandth of a millimetre) surrounded by a membrane and hosts the cytoplasm, the nucleus and a number of organelles. The cytoplasm resembles jelly-like substances and is in continuous movement, with the nucleus containing the genetic code of the neuron that is used for protein synthesis (e.g. of some types of neurotransmitters). The neuron’s metabolism is dependent on the organelles that perform chemical synthesis, generate and store energy; and provide the structural support (similar to a skeleton) for the neuron.

Secondly, we have the dendrites [derived from Greek ‘Dendron’] which are branched cellular extensions emanating from the cell body that receive most of the synaptic contacts from other neurons. It is important to note that dendrites only receive information from other neurons and cannot transmit any of it to them; their purpose is to propagate information to the axon.

Thirdly, axons which can measure from up to a few millimetres to one metre in length, transmit information from the soma to other neurons, ending with the terminal buttons which store chemicals used for inter-neuron communication. There are 2 types of axons. The first type – myelinated axons – are covered with a fatty, white substance known as myelin which is a sheath that has gaps at places known as the nodes of Ranvier. Myelin acts as a catalyst in making electric transmission faster and more efficient by insulating the axon. Hence, with myelinated axons, myelin is vital for effective electric transmission, and its loss leads to serious neurological diseases such as multiple sclerosis, The second type of axons are not covered by myelin, resulting in a slower electric transmission.ANeuron

TheNeuron

Neurons are always active, even when no information is being received from other neurons, and must feed themselves (through blood vessels), maintain physiological parameters within a certain range (homeostasis), and maintain their electrical equilibrium, which is essential in the transmission of information.

The terminal buttons [also known as Axon terminals] are button-like endings of the axon branches which release the information to other neurons via neurotransmitter molecules through synaptic vesicles stored within itself. The neurotransmitter is then diffused across the synaptic cleft [gap between 2 membranes] where a depolarisation from incoming action potentials lead to the opening of Calcium channels and Ca+ triggers vesicles to fuse with pre-synaptic membrane, releasing the neurotransmitter into the synaptic cleft which diffuses across and binds with receptors of the next neuron’s post-synaptic membrane’s receptors; causing particular ion channels to open.

synaptic cleft

Post synaptic potentials further defines the opening credentials. Excitatory Post Synaptic Potential (EPSP) is the result of depolarisation (+ve) which increases the positive charge after allowing Sodium (Na+) ions inside. Another result could be an Inhibitory Post Synaptic Potential (IPSP) which would be caused by the hyperpolarisation (-ve) due to the opening of Chloride (Cl-) channels. The summation carried out by the Axon Hillock calculates whether it reaches the threshold, if it does; an Action Potential in the Postsynaptic Neuron is triggered and excess neurotransmitter is taken back by the pre-synaptic neuron and degraded by enzymes.

The Neural Signature of Learning

Learning is the process through which memories are formed and it is assumed to be the result of enduring changes in the synapses between neurons – a mechanism called long-term potentiation (LTP), which is the strengthening of connections between two neurons by the synaptic chemical change. Memory storage is the strengthening or weakening of synaptic connections. Hebbian learning is a key principle for long-term potentiation (LTP)“neurons that fire together, wire together” (Hebb, 1949), meaning that any two cells or system of cells that are repeatedly active at the same time will tend to become ‘associated’ – and recent studies seem to also suggest that the growth of new synapses foster learning. A new memory is a change to the nervous system as a result of learning, i.e. a memory is the internal representation of knowledge acquired through experience.

New experiences change the nervous system, a phenomenon known as “neuroplasticity”. One solid example of this process of neuroplasticity is given in the study done by Maguire et al. (2000): where the volume of the hippocampus [an area of the brain essential for learning & memory] of London Taxi Drivers were compared with that of a control group, with the hypothesis that extensive experience with spatial navigation and resulting increase in spatial memory might have led to enduring changes in the brain. Eventually, as predicted the hippocampal volume of the London Taxi Drivers was significantly larger than the normal people in the control group. Furthermore, the hippocampal volume in the taxi drivers correlated positively with the amount of time spent on the job. From such an experiment, it was deduced that new experiences can still change the nervous system in adulthood.

Hebb argued convincingly that enduring changes in the efficiency of synaptic transmission were the basis of long-term memory. If we assume that the repetition of a reverberatory activity induces lasting cellular changes that adds to its stability when an axon of Cell A is near enough to excite a Cell B and repeatedly takes part in its activation, some growth process or metabolic change takes place in one or both cells such that Cell A’s efficiency as one of the cells activating Cell B is increased.

Scientific evidence for Hebb’s law has been repeatedly found, i.e. when a neuron fires, an action potential travels to the end of the axon, where synaptic vesicles release neurotransmitters into the synaptic cleft, these neurotransmitters bind to the postsynaptic receptors on dendrite and trigger an action potential in the next neuron. The strength of such a synaptic connection between neurons is not fixed, but depends on the amount of postsynaptic receptors, the sensitivity of the postsynaptic receptors and the amount of neurotransmitters released by the presynaptic neuron. Correlated activity of presynaptic and postsynaptic neurons result in an increase in the strength of this synaptic connection between neurons, known as long-term potentiation [first observed by Terje Lomo in 1966]. This is the neural signature of learning.

A neuron codes information through its “spiking rate”
 [response rate] which is the number of action potentials propagated per second. Some neurons may have  a high spiking rate in some situations (e.g. during speech), but not others (e.g. during vision), while others may simply have a complementary profile. Neurons that respond to the same type of information are generally grouped together, this leads to the functional specialisation of brain regions. The input a neuron receives and the output that it sends to another neuron is related to the type of information a neuron carries. For example, information about sounds is only processed by the primary auditory cortex because this region’s inputs are from a pathway originating in the cochlea and they also send information to other neurons involved in a more advanced stage of auditory processing (e.g. speech perception). For example, if it were possible to rewire the brain such that the primary auditory cortex was to receive inputs from the retinal pathway instead of the auditory pathway (Sur & Leamey, 2001), the function of that part of the brain would have changed [along with the type of information it carries] even if the regions themselves remained static [with only inputs rewired]. This is worthy of being noted as when one considers the function of a particular cerebral region: the function of any brain region is determined by its inputs and outputs – hence, the extent to which a function can only be achieved at a particular location is a subject open to debate.

Gray matter, white matter and cerebrospinal fluid

Neurons in the brain are structured to form white matter [axons and support cells: glia] and gray matter [neuronal cell bodies]. The white matter lies underneath the highly convoluted folded sheet of gray matter [cerebral cortex]. Beneath the white matter fibers, there is another collection of gray matter structures [subcortex], which includes the basal ganglia, the limbic system, and the diencephalon. White matter tracts may project between different regions of the cortex within the same hemisphere [known as association tracts) and also between regions across different hemispheres [known as commissures; with the most important being the corpus callosum]; or may project between cortical and subcortical regions [known as projection tracts]. A number of hollow chambers called ventricles also form part of the brain, these are filled with cerebrospinal fluid (CSF), which serves important functions such as carrying waste metabolites, transferring messenger signals while providing a protective cushion for the brain.


Reflections: From biology to psychology

In the classic essay on the “Architecture of Complexity”, Simon (1996) noted that hierarchies are present everywhere at every level in natural systems – taking the field of physics as an example, in particular the way elementary particles form atoms, atoms form molecules, and molecules form more complex entities such as rocks. Furthering this metaphor as an example, we may also wish to look at the organisation of a book: letters, words, sentences, paragraphs, sections and finally chapters.

In biological systems, a similar type of hierarchical structure can be found at many levels, particularly in the way the brain is organised. Simon seems to convincingly argue that complex systems’ evolution would have had to have benefited from some degree of stability, which is precisely enabled by hierarchical organisation. The main idea is that hierarchical organisations typically have a degree of redundancy – that is, the same functions at the particular level can be carried out by different components; and if one component fails, the system is only slightly affected since other components could perform the functions to some extent. Systems that lack systematic hierarchical organisation tend to lack this degree of flexibility, and a system as complex as the human brain must have a strong hierarchical organisation, or it would not have been able to evolve into such a complex organ.

HierarchyOfTheCentralNervousSystemTheHumanLimbicSystem.jpg

Using the Limbic system [diagram above] as an example of each level’s specialisation, it is possible to understand how it is responsible for a particular set of functions related but also separate from other parts of the brain. The Limbic system is essential in allowing the human organism to relate to its environment based on current needs and the present situation with experience gathered. This very intriguing part of the brain may in fact be the source of – what many might call – “Humanity” in man as it is responsible for the detection and subsequent expression of emotional responses. One of its parts, the amygdala is implicated in the detection of fearful or threatening stimuli, while parts of the cingulate gyrusare involved in the detection of emotional and cognitive conflicts. Another part, the hippocampus is of major importance in learning and memory; it lies buried in the temporal lobes of each hemisphere along with the amygdala. Other structures of the Limbic system are only visible from the ventral surface [underside] of the brain; the mamillary bodies are two small round protrusions that have traditionally been implicated in memory (Dusoir et al., 1990), while the olfactory bulbs are located under the surface of the frontal lobes with their connections to the limbic system underscoring the importance of smell for detecting environmentally salient stimuli (e.g. food, animals, cattle, cars, etc) and its influence on mood and memory.

One of the main insight of Simon’s analysis is that scientists should be thankful to nature for the existence of hierarchies, since they make the task of understanding the mechanisms involved easierIt can be achieved by simply focusing on one specific level rather than trying to understand the phenomena in all its complexities – because each level has its own laws and principles. On initial approximation, what happens at lower levels may end up being averaged without taking into account all the details and the happenings at the higher levels, which may unfairly be considered as constant.

AttenboroughDarwin

Naturalist, David Attenborough / Image: Darwin & the tree of life (2009)

Focusing on a popular example, we could look at the biologist and naturalist Charles Darwin when he formulated his theory of evolution. At that time, the structure of DNA [which would be discovered 70 years later] was not a major concern of his, furthermore the latter did not have to consider the way the Earth came to exist. Instead, what the biologist did was to focus on an intermediate level in the hierarchy of natural phenomena (e.g. primates, animals, birds, insects, etc): how species evolved over time. Such example also seems to illustrate a vital point in this analysis: the processes involved at the level we are interested in can be understood by analysing the constraints provided by the levels below and above. What happens at the low levels (e.g. the biochemical level) and what happens at high levels (e.g. the cosmological level) limit how any species evolve; and if the biochemistry of life had been disrupted, and if our planet did not provide the appropriate environmental elements and conditions for life to flourish, evolution would simply not have happened. As science progresses and shatters many outdated perspectives at looking at life & nature on planet Earth, links are being made between these different levels of explanation.

It is now firmly accepted among intellectuals from evidence gathered in Biopsychology (also known as Neuroscience) that the acquisition of skills is dependent on an organism’s ability to learn and develop throughout its lifetime, and DNA is an important factor at the biochemical level for the transmission of heredity traits postulated by Charles Darwin. Hence, human evolution is a process that is continuous, multifaceted, complex, creative & ongoing; and intelligent design [e.g. psychological, educational, linguistic, biological, genetic, philosophical, environmental, dietary, etc] is an undeniably important factor for the intelligent evolution of human societies.

EverythingPossibleUglyFactHuxley

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References

  1. Azevedo, F.A.C., Carvalho, L.R.B., Grinberg, L.T., Farfel, J.M., Ferretti, R.E.L., Leite, R.E.P., Jacob Filho, W., Lent, R. & Herculano-Houzel, S. (2009) Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain. Journal of Comparative Neurolology , 513 , 532-541.
  2. Dusoir, H., Kapur, N., Byrnes, D. P., McKinstry, S., & Hoare, R. D. (1990). The role of diencephalic pathology in human-memory disorder-evidence from a penetrating paranasal brain injury. Brain , 113 , 1695-1706.
  3. Gobet, F., Chassy, P. and Bilalic, M. (2011). Foundations of cognitive psychology. 1st ed. New York: McGraw-Hill Higher Education.
  4. Hebb, D. O. (1949). Organization of behaviour. NJ: Wiley and Sons.
  5. Lomo, T. (2003). The discovery of long-term potentiation. Philosophical Transactions of the Royal Society B: Biological Sciences, 358(1432), pp.617-620.
  6. Maguire, E., Gadian, D., Johnsrude, I., Good, C., Ashburner, J., Frackowiak, R. and Frith, C. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences, 97(8), pp.4398-4403.
  7. Pinel, J. (2014). Biopsychology 8th ed. Harlow: Pearson.
  8. Simon, H. A. (1996). The sciences of the artificial (3rd edn). Cambridge: The MIT Press.
  9. Sur, M. & Leamey, C. A. (2001). Development and plasticity of cortical areas and networks. Nature Reviews Neuroscience , 2 , 251-262.

Updated: 15th of June 2018 | Danny J. D’Purb | DPURB.com

____________________________________________________

While the aim of the community at dpurb.com has  been & will always be to focus on a modern & progressive culture, human progress, scientific research, philosophical advancement & a future in harmony with our natural environment; the tireless efforts in researching & providing our valued audience the latest & finest information in various fields unfortunately takes its toll on our very human admins, who along with the time sacrificed & the pleasure of contributing in advancing our world through sensitive discussions & progressive ideas, have to deal with the stresses that test even the toughest of minds. Your valued support would ensure our work remains at its standards and remind our admins that their efforts are appreciated while also allowing you to take pride in our journey towards an enlightened human civilization. Your support would benefit a cause that focuses on mankind, current & future generations.

Thank you once again for your time.

Please feel free to support us by considering a donation.

Sincerely,

The Team @ dpurb.com

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Essay // Biopsychology | The Temporal Lobes: Vision, Sound & Awareness

The temporal lobe consists of all the tissues located underneath the lateral (Sylvian) fissure and anterior to the occipital cortex (FIGURE A). The subcortical temporal lobe structures include the limbic cortex, the amygdala, and the hippocampal formation (FIGURE B). The connections to and from the temporal lobe extend to all areas of the brain. Typical symptoms of temporal-lobe disorder or damage generally include drastic deficits in affect and personality, memory problems, and some form of deficits of language.

001 sylvian

FIGURE A. Anatomy of the Temporal Lobe | (A) The 3 Major gyri visible on the lateral surface of the temporal lobe. (B) Brodmann’s cytoarchitectonic zones on the lateral surface. Auditory areas are shown in yellow and visual areas in purple. Areas 20, 21, 37 and 38 are often referred to by von Economo’s designation, TE. (C) The gyri visible on a medial view of the temporal lobe. The uncus refers to the anterior extension of the hippocampal formation. The parahippocampal gyrus includes areas TF and TH.

002 sylvian

FIGURE B. Internal Structure of the Temporal Lobe | (TOP) Lateral View of the left hemisphere showing the positions of the amygdala and the hippocampus buried deeply in the temporal lobe. The vertical lines show the approximate location of the coronal sections in the bottom illustration. (BOTTOM) Frontal views through the left hemisphere illustrating the cortical and subcortical regions of the temporal lobe.

Subdivisions of the Temporal Cortex

10 temporal areas were identified by Brodman, however many more have recently been discovered in monkeys, and this finding suggests that humans too may have many more areas to explore. The temporal areas on the lateral surface can be divided into those that are auditory (FIG. A. (B), Brodman areas 41, 42 and 22) and those that make up the Ventral Visual Stream on the lateral temporal lobe (FIG. A. (B), areas 20, 21, 37 & 38). These regions specific to vision are often referred to as the Inferotemporal Cortex or by von Economo’s designation, TE.

003 Rhesus.jpg

FIGURE C. Cytoarchitectonic Regions of the Temporal Cortex of the Rhesus Monkey | (A) Brodmann’s Areas. (B) Von Bonin and Bailey’s Areas. (C and D) Lateral and ventral views of Seltzer and Pandya’s parcellation showing the multimodal areas in the superior temporal sulcus. Subareas revealed in part C are generally NOT visible from the surface.

A huge amount of cortex can be found within the sulci of the temporal lobe as shown in the frontal views at the bottom of FIGURE B, particularly the lateral (Sylvian) fissure which contains the tissue forming the insula: an area that includes the gustatory cortex and the auditory association cortex. The Superior Temporal Sulcus (STS) divides the superior and middle temporal gyri, and also contains a fair amount of neocortex. FIGURE C. shows the many subregions of the Superior Temporal Sulcus, the multi-modal, or polymodal cortex that receives input from auditory, visual, and somatic regions, and from another two polymodal regions (frontal & parietal) along with the paralimbic cortex.

005 MultiMonkeyCortex

FIGURE D. Mutlisensory Areas in the Monkey Cortex | Coloured areas represent regions where anatomical or electrophysiological data or both types demonstrate multisensory interactions. Dashed lines represent open sulci. (After Ghazanfar and Schroeder, 2006.)

The medial temporal region (limbic cortex) includes the amygdala and the adjacent cortex (uncus), the hippocampus and surrounding cortex (subiculum, entorhinal cortex, perirhinal cortex), and the fusiform gyrus (see FIGURE B). The entorhinal cortex is Brodmann’s area 28, and the perirhinal cortex comprises Brodmann’s areas 35 and 36.

Cortical areas TH and TF at the posterior end of the temporal lobe (see FIGURE C) are often referred to as the parahippocampal cortex. The fusiform gyrus and the inferior temporal gyrus are functional parts of the lateral temporal cortex (see FIGURE A and FIGURE B).

Connections of the Temporal Cortex

One major fact about the temporal lobes is that they are rich in internal connections, afferent projections from the sensory systems, and efferent projections to the parietal and frontal association regions, limbic system, and basal ganglia. The corpus callosum connects the neocortex of the left and right temporal lobes, whereas the anterior commissure connects connects the temporal cortex and the amygdala.

006 CorpusCallosumAnteriorComissure

004 Connections

FIGURE E. Major Intracortical Connections of the Temporal Lobe | (A) Auditory and visual information progresses ventrally from the primary regions toward the temporal pole en route to the medial temporal regions. Auditory information also forms a dorsal pathway to the posterior parietal lobe. (B) Auditory, visual, and somatic outputs go to the multimodal regions of the superior temporal sulcus (STS). (C) Auditory and visual information goes to the medial temporal region, including the amygdala and the hippocampal formation.  (D) Auditory and visual information goes to two prefrontal regions, one on the dorsolateral surface and the other in the orbital region (area 13).

Five distinct types of cortical-cortical connections have been revealed through studies on the temporocortical connections of the monkey (see FIGURE E), and each projection pathway subserves a particular function:

  1. A Hierarchical Sensory Pathway. This pathway is essential for stimulus recognition. The hierarchical progress of connections derives from the primary and secondary auditory and visual areas, ending in the temporal pole (see FIGURE E (A)). The visual projections form the ventral stream of visual processing , whereas the auditory projections form a parallel ventral stream of auditory processing.
  2. A Dorsal Auditory Pathway. Projecting from the auditory areas to the posterior parietal cortex (FIGURE E(A)), the pathway is analogous to the dorsal visual pathway and thus concerned with directing movements with respect to auditory information. The dorsal auditory pathway likely has a role to play in the detection of the spatial location of auditory inputs.
  3. A Polymodal Pathway. This pathway is a series of parallel projections from the visual and auditory association areas into the polymodal regions of the superior temporal sulcus (see FIGURE E(B)). The polymodal pathway seems to underlie the categorisation of stimuli.
  4. A Medial Temporal Projection. Vital for long-term memory, the projection from the auditory and visual association areas into the medial temporal, or limbic, regions goes first to the perirhinal cortex, then to the entorhinal cortex, and finally into the hippocampal formation or the amygdala or both (see FIGURE E(C)). The hippocampal projection forms the perforant pathway – disturbance of this projection leads to major dysfunction in hippocampal activity.
  5. A frontal-lobe projection. This series of parallel projections, necessary for various aspects of movement control, short-term memory, and affect, reaches from the temporal association areas to the frontal lobe (see FIGURE E(D)).

These five projection pathways play a unique and major role in temporal-lobe functions.

A Theory of Temporal Lobe Functions

The temporal lobe is multi-functional and comprises the primary auditory cortex, the secondary auditory and visual cortex, the limbic cortex, and the amygdala and hippocampus. The hippocampus works in combination with the object-recognition and memory functions of the neocortex and has a fundamental role in organising memories of objects in space. The amygdala is also responsible for adding affective tone (emotions) to sensory input and memories.

Based on the cortical anatomy, 3 basic sensory functions of the temporal cortex can be identified:

  1. Processing auditory input
  2. Visual object recognition
  3. Long-term storage of sensory input

Temporal-lobe functions are best explained by considering how the brain analyses and processes sensory stimuli as they enter the nervous system. A good example would be a hike in the woods where on a journey, one would notice a wide variety of birds. Furthering this example, let us assume that the individual on the hike decides to keep a mental list of all the birds encountered to report to his/her sister who happens to be an avid nature lover and birder. Now let us assume that the individual upon exploring has encountered a rattlesnake in the middle of his/her path; it is highly likely that he/she would change direction and look for birds in a safer location. Let us now consider the temporal-lobe functions engaged in such activity.

Sensory Processes

We shall use the hiking example above to explain the processes as we progress. In the case of birds of different types, the awareness of specific colours, shapes and sizes would be vital, and such a process involving object recognition is the function of the ventral visual pathway in the temporal lobe.

Speed is also of the essence in such natural situations since birds may not remain static for extended amounts of time, thus, we would tend to spot them fast from sighting to sighting (e.g. lateral view vs rear view). The development of categories for object types is vital to both perception and memory, and this depends on the inferortemporal cortex. The process of categorisation may also require some form of directed attention, since some aspects of a stimuli tend to play a more important role in the process of classification than do others [e.g. language, culture & speech in human beings].

For example, classifying two different types of yellow birds would require attention to be directed away from colour, to instead focus on shape, size and other individual characteristics. It has been revealed that damage to the temporal cortex leads to deficits in identifying and categorising stimuli. However, such a patient would have no difficulty in the location of stimulus or in recognising that the object is physically present, since these activities are functions of another part of the brain: the posterior parietal and primary sensory areas respectively.

As the individual would continue the journey to spot birds, he/she may also hear a bird song, and this stimulus would also have to be matched with the visual input. This process of matching visual and auditory information is known as cross-modal matching, and likely depends on the cortex of the superior temporal sulcus.

As the journey progresses, the individual may come across more and more birds which would require the formation of memory for later retrieval of their specificity. Furthermore, as the birds vary, their respective names would have to be accessed from memory; these long-term memory processes depend on the entire ventral visual stream as well as the paralimbic cortex of the medial temporal region.

Affective Responses

Using the encounter with the snake as an example, the individual would first hear the rattle, which is an alert of the reptilian danger, and stop. Next, the ground would have to be scanned visually to spot the venomous creature, to identity it while dealing with a rising heart rate and blood pressure. The affective response in such a situation would be the function of the amygdala. The association of sensory input (stimulus) and emotion is crucial for learning, because specific stimuli become associated with their positive, negative or neutral consequences, and behaviour is shaped/modified accordingly.

If such an affective system was to be cancelled out from a person’s brain, all stimuli would be treated equallyconsider the consequences of failing to associate a rattlesnake, which is venomous, with the consequences of being bitten. Furthering the example, consider an individual who is unable to associate good & positive feelings (such as honesty, warmth, trust & human love) to a specific person.

Laboratory animals with amygdala lesions/damage generally become extremely placid and lack any form of emotional reaction to threatening stimuli. For example, monkeys that were formerly terrified of snakes become indifferent to them [and of the fatal consequences] and may reach and pick them up.
Spatial Navigation

When the decision to change directions is made by the individual, the hippocampus becomes active and it contains cells that code places in space that allow us to navigate in space and remember our position [location].

As the general functions of the temporal lobes [sensory, affective & navigational] are considered it is fairly obvious how devastating the consequences on behaviour would be for a person who loses them: the inability to perceive or remember events, including language and loss of affect. However, such a person lacking temporal-lobe function would still be able to use the dorsal visual system to make visually guided movements and under many circumstances, would shockingly appear completely normal to many.

The Superior Temporal Sulcus & Biological Motion

The hiking example above has lacked an additional temporal-lobe function, a process that most animals engage in known as biological motion: movements that have particular relevance to a particular species. For example, among humans in Western Europe, many movements involving the eyes, face, mouth, hands and body have social meanings – the superior temporal sulcus analyses biological motion.

007 Superior Temporal Sulcus

FIGURE F. Biological Motion | Summary of the activation (indicated by dots) of the Superior Temporal Sulcus (STS) region in the left (A) and right (B) hemispheres during the perception of biological motion. (After Allison, Puce, and McCarthy, 2000.)

The STS plays a role in categorising stimuli from received multimodal inputs. One major category is social perception, which involves the analysis and response of actual or implied bodily movements that provide socially relevant information about a person’s actual state. Such information has an important role to play in social cognition, or « Theory of Mind », that allows us to develop hypotheses about another individual’s intentions. For example, the direction of an individual’s gaze provides some information about what that person is attending (or not attending) to.

In a review, Truett Allison and colleagues proposed that cells in the superior temporal sulcus have a key role to play in social cognition. For example, cells in the monkey STS respond to various forms of biological motion including the direction of eye gaze, facial expression, mouth movement, head movement and hand movement.

In the case of advanced social animals such as primates, the ability to understand and respond to biological motion is critical information needed to infer the intention of others. As shown in FIGURE F , imaging studies revealed the activation along the STS during the perception of a variety of biological motion.

One major correlate of mouth movements is vocalisation, and so it is possible to predict that regions of the STS are also implicated in perceiving the specific sounds of a particular species. In monkeys for example, cells in the Superior Temporal Gyrus, which is adjacent to the STS and sends connections to it, show a preference for « monkey calls ». In humans too, imaging studies have revealed that the superior temporal gyrus is activated by both human vocalisations and by melodic sequences.

The activation in some part of the superior temporal sulcus in response to a combination of visual stimulus (mouth movements) and talking or singing could be predicted, and presumably sophisticated speech and vocal performances (singing) are perceived as complex forms of biological motion. Hence, it is fairly obvious that people with temporal-lobe injuries that lead to impairments in the analysis of biological motion will likely be correlated with deficit in social awareness/judgement. Indeed, the studies of David Perrett and his colleagues illustrate the nature of processing in the STS, who revealed that neurons in the superior temporal sulcus may be responsive to particular faces viewed head-on, faces viewed in profile, the posture of the head, or even the specific facial expressions. Perrett also found that some STS cells are extremely sensitive to primate bodies that move in a particular direction, another characteristic biological motion (see FIGURE G below). Such finding is quite remarkable since the basic configuration of the primate stimulus remains identical as it moves in different directions; solely the direction changes.

008 NeuronalSensitivity

FIGURE G. Neuronal Sensitivity to Direction of Body Movements | (Top) Schematic representation of the front view of a body. (Bottom) The histogram illustrates a greater neuronal response of STS neurons to the front view of a body that approaches the observing monkey compared with the responses to the same view of the body when the body is moving away, to the right and to the left, or is stationary. (After Perrett et al., 1990.)


Visual Processing in the Temporal Lobe

visualstream

All visual information goes through the Lateral Geniculate Nucleus (LGN) which is part of the thalamus. The LGN directs visual information into the brain where most of it is sent straight to the occipital cortex/lobe. The dorsal and ventral streams are primary pathways to visual cortex V1 located around the calcarine fissure in the occipital lobe [V1 is critical for sight, loss leads to blindness]. It is believed that human beings possess two distinct visual systems.

When visual information leaves the occipital lobe (visual cortex), it follows two streams:

1) The Ventral Stream begins with V1 and passes through vision region V2, then V4 and to the inferior temporal cortex. It is known as the “What Pathway” and is responsible for processes related to form recognition and object representation; and is also linked to the formation of long-term memory. The ventral stream is associated to a concept of “vision in the brain”, which allows humans to make sense of the visual information they receive. Vartanian & Skov (2014) have recently found activity in the anterior insula [emotion experiencing part] and in the ventral stream when viewing art paintings. Sustained damage to the ventral stream would allow a subject to see, perceive colours, movements, understand the underlying expectation of meaning to an object or face; but yet fail to perceive “what” the object/face is. This condition is known as agnosia which means the “failure to know”; where patients lose the ability to identify by sight but have no difficulties with memory for word or descriptive language.

OpticRadiations56Visual agnosia appears to be the result of not a primary vision problem but an associative function in the brain to give definition.

Lissauer (1890) defined 2 types of visual agnosias; apperceptive visual agnosia and associative visual agnosia.

In the apperceptive type subjects cannot identify, draw, copy but identify the object upon touch (Benson and Greenberg, 1969). In associative visual agnosia, subjects can “perceive” the object but cannot associate it with correct vocabulary; showing that the knowledge is present along with touch recognition and verbal description but not object identification; although they can copy even if extensive time is taken on simple figures.

2) The Dorsal Stream also known as the “where” stream begins with V1, goes through vision region V2, then through the dorsomedial area and V5, then to the posterior parietal cortex. Known as the “Where” or “How” Pathway it is believed to play a major part in the processing of motion, location of particular objects in the viewer’s range, fine motor controls of the arms and eyes. Damage to the dorsal stream disrupts visual spatial perception and visually guided behaviour; but not conscious visual perception.

The famous case of A.T the woman who could not grasp unfamiliar objects seen had her dorsal route interrupted due to a lesion of the occipitoparietal region. She was able to recognise objects & demonstrate size with fingers but was incorrect in object directed movements along with ability to properly grip with her fingers; instead tried grabbing awkwardly with bad finger synchronisation.


FFA [Fusiform Face Area] & PPA [Parahippocampal Place Area]

010 FFA&amp;PPA

The selective activation of the FFA [Fusiform Face Area] an the PPA [Parahippocampal Place Area] related to categories of visual stimulation that include a wide range of different exemplars of the specific categories raises the interesting question of how such dissimilar objects could be  treated equivalently by specialised cortical regions. Different views of the same object are not only linked together as being the same, but different objects appear to be linked together as being part of the same category as well. Such an automatic categorisation of sensory information has to be partially learned since most humans categorise unnatural objects such as cars or furniture; the brain is unlikely to be innately designed for such categorisations.

To understand how the brain learns such processes, researchers have looked for changes in neuronal activity as subjects learn categories. Kenji Tanaka started by attempting to determine the critical features for activating neurons in the monkey inferotemporal cortex. Tanaka and his colleagues presented a range of three-dimensional animal and plant representations to find the effective stimuli for specific cells, then they tried to determine the necessary and sufficient properties of theses cells. They found that most cells in the TE (see FIGURE C) require complex features for activation such as orientation, size, colour and texture.

009 ColumnarOrganisation

FIGURE H. Columnar Organisation in Area TE | Cells with similar but slightly different selectivity cluster in elongated vertical columns, perpendicular to the cortical surface.

As shown in FIGURE H, Tanaka has found that cells with similar, although slightly different selectivity, tend to cluster vertically in columns. These cells were not similar in their stimulus selectivity; so an object is likely represented not by the the activity of a single cell but rather by the activity of many cells within a columnar module.

Two remarkable features of the inferotemporal neurons in monkeys have also been described by Tanaka and others. First, the stimulus specificity of these neurons is altered by experience. In a period of one year, monkeys were trained to discriminate 28 complex shapes. The stimulus preferences of inferotemporal neurons were then determined from a larger set of animal and plant models. Among the trained monkeys, 39% of the inferotemporal neurons gave a maximum response to some of the stimuli used in the training process, compared with only 9% of the neurons in the naïve monkeys.

These results confirm that the temporal lobe’s role in visual processing is not fully determined genetically but is subject to experience even in adults. It can be speculated that such experience-dependent characteristics allows the visual system to adapt to different demands in a changing visual environment. This is a feature important for human visual recognition abilities that have demands in forests that greatly differ from those on open plains or in urban environments. Furthermore, experience-dependent visual neurons ensure that we can identify visual stimuli that were never encountered in the evolution of the human brain.

The second interesting feature of inferotemporal neurons is that they may not only process visual input but also provide a mechanism for the internal representation of the images of objects. Joaquin Fuster and John Jervey demonstrated that, if monkeys are shown specific objects that are to be remembered, neurons in the monkey cortex continue to discharge during the « memory » period. Such selective discharges of neurons may provide the basis for visual imagery, i.e. the discharge of groups of neurons that are selective for characteristics of particular objects may create a mental image of the object in its absence.

Could human faces be special?

La Joconde (1503 - 1506) Léonard de Vinci dpurb d'purb website

« La Joconde » par Léonard de Vinci (1503 – 1519)

Most humans on earth spend more time in the analysis of faces that any other single stimulus. Infants tend to look at faces from birth while adults are particularly skilled at identifying faces despite large variations in the expressions and viewing angles, even when the faces are modified visually [with beards, spectacles, or hats]. Faces also have an incredible number of muscles to convey a wealth of social information, and humans are unique among all primate species in spending a great deal of time in looking directly at a wide range of faces from other members of our species on earth. The importance of faces as visual stimuli has led to the assumption that special pathways exist specifically for human faces, and several lines of evidence support the view. 

012 HumanNeuralSystemForFacePerception

FIGURE I. A Model of Distributed Human Neural System for Face Perception | The model is divided into a core system (TOP), consisting of occipital and temporal regions, and an extended system (BOTTOM), including regions that are part of neural systems for other cognitive functions. (After Haxby, Hoffman, and Gobbini, 2000.)

The face-perception system is extensive and includes regions in the occipital lobe as well as several different regions of the temporal lobe. Figure I above summarises a model by Haxby and his colleagues in which different aspects of facial perception (such as facial perception VS identity) are analysed in core visual areas in the temporal part of the visual stream. This model has also included other cortical regions as an « extended system » that includes the analysis of other facial characteristics such as emotion and lip reading. The key point to note is that the analysis of human faces is unlike any other stimuli: faces may indeed be special objects to the brain. A clear asymmetry exists in the role of the temporal lobes in facial analysis: right temporal lesions/damage have a greater effect on facial processing that do similar left temporal lesions/damage. Even in normal subjects, researchers have noted the asymmetry in face perception.

011 SplitFacesTest

FIGURE J. The Split-Faces Test | Subjects were asked which of the two pictures, B or C, most closely resembles picture A. Control subjects chose picture C significantly more often than picture B. Picture C corresponds to that part of picture A falling in a subject’s left visual fied. The woman pictured chose B, closer to the view that she is accustomed to seeing in the mirror. (After Kolb, Milner, and Taylor, 1983).

Photographs of faces as illustrated in FIGURE J, were presented to subjects. Photographs B and C are composites of the right or left sides, respectively, of the original face shown in Photograph A. When asked to identify the composite most similar to the original face, normal subjects consistently matched the left side of photograph A to its composite in photograph C. Participants did so whether the photographs were presented inverted or upright. Furthermore, patients with either right temporal or right parietal removals failed to consistently match either side of the face in either the inverted or upright scenario.

These results of the split-faces do not simply provide evidence for asymmetry in facial processing but also raises the issue of the nature of our perceptions of our own faces. Self-perception seems to provide a unique example of visual perception, since the image of our face tends to come from the mirror whereas the image that the world has of our face comes from each individuals direct view, and the inspection of FIGURE J illustrates the implications of this difference.

Photograph A is the image that most people perceive of the female subject shown above. Since humans have a left-visual-field bias in their perception, most right-handers choose photograph C as the picture most resembling the original A. However, upon asking the female subject in the photograph to choose the photograph most resembling her, she chose photograph B, as her common view of herself in the mirror seemed to match her choice although it is the reverse of most other people.

This intriguing consequence is the simple result of most people’s biased self-facial image of their opinion of personal photographs. Members of the general public tend to complain about their photographs not being photogenic, that their photographs are never taken at the correct angle, and other complaints about the image. The truth is that the problem may be rather different: people are accustomed to seeing themselves in the mirror and hence when a photograph is presented, most are biased to look at the side of the face that is not normally perceived selectively in the mirror, hence the person has a glimpse of himself/herself from the eyes of the rest of the world. Indeed people tend to not see themselves as others see them – the greater the asymmetry of a human face, the less flattering the person will see his or her image to be.

One major critical question about facial processing and the FFA remains however. Some researchers have argued that although face recognition appears to tap into a specialised face area, the exact same region could be used for other forms of expertise and is not specific for faces. For example, imaging studies have revealed that real-world experts show an overlapping pattern of activation in the FFA for faces in control participants, for car stimuli in car experts, and for bird stimuli in bird experts. The main scientific view is that the FFA is fairly plastic as a consequence of perceptual experience and training, and is innately biased to categorise complex objects such as faces but can also be recruited for other forms of visual categorisation expertise.

Does Your Face Tell People How Healthy You Are

Study: Does your face tell people how healthy you are? / Henderson, A., Holzleitner, I., Talamas, S. and Perrett, D. (2016). Perception of health from facial cues. Philosophical Transactions of the Royal Society B: Biological Sciences, 371(1693), p.20150380.


Auditory Processing in the Temporal Lobe

A cascade of mechanical and neural events in the cochlea, the brainstem, and, eventually, the auditory cortex that results in the percept of sound is stimulated whenever a sound reaches the ear. Similarly to the visual cortex, the auditory cortex has multiple regions, each of which has a tonotopic map.

015 Auditory Mapping.jpg

Although the precise functions of these maps are still to be fully understood, the ultimate goal lies in the perception of sound objects, the localisation of sound, and the decision about movements in relation to sounds. A great amount of cells in the auditory cortex respond only to specific frequencies, and these are often referred to as sound pitches or to multiples of those frequencies. Two of the main and most important types of sound for humans are music & language.

Speech Perception

Unlike any other auditory input, human speech differs in three fundamental ways.

  1. Speech sounds come mainly from three restricted ranges of frequencies, which are known as formants. FIGURE K(A) shows sound spectrograms of different two-formant syllables. The dark bars indicate the frequency bands seen in more detail in FIGURE K(B), which shows that the syllables differ both in the onset frequency of the second (higher) formant and in the onset time of the consonant. Notice that vowel sounds are in a constant frequency band, but consonants show rapid changes in frenquency.
  2. The similar speech sounds vary from one context in which they are heard to another, yet all are perceived as being the same. Thus, the sound spectrogram of the letter « d » in English is different in the words « deep », « deck » and « duke », yet a listener perceives all of them as « d ». The auditory system must have a mechanism for categorising varying sounds as being equivalent, and this mechanism must be affected by experience because a major obstacle to learning a new language in adulthood remains the difficulty of learning equivalent sound categories. Thus, a word’s spectrogram depends on the context – the words that precede and follow it (there may be a parallel mechanism for musical categorisation).
  3. Speech sounds also change very rapidly in relation to one another, and the sequential order of the sounds is critical to understanding. According to Alvin Liberman, humans can perceive speech at rates of as many as 30 segments per second. Speech perception at the higher rates is truly astonishing, because it far exceeds the auditory system’s ability to transmit all the speech as separate pieces of auditory information. For example, non-speech noise is perceived as a buzz at a rate of only about 5 segments per second.It seems fairly obvious that the brain must recognise and analyse language sounds in a very special way, similar to the echolocation system of the bat which is specialised in the bat brain. It is highly probable that the special mechanism for speech perception is located on the left temporal lobe. This function may not be unique to humans, since the results of studies in both monkeys and rats show specific deficits in the perception of species-typical vocalisations after left temporal lesions.
013 Speech Sounds

FIGURE K. Speech Sounds | (A) Schematic spectrograms of three different syllables, each made up of two formants. (B) Spectrograms of syllables differing in voice onset time. (After Springer, 1979.)


Music Perception

Music is different from language since it relies on the relations between auditory elements rather than on individual elements. And a tune is not defined by the pitches of the tones that constitute it but by the arrangement of the pitches’ duration and the intervals between them. Musical sounds may differ from one another in three major aspects: pitch (frequency), loudness (amplitude) and timbre (complexity).

014 BreakingDownSound

FIGURE L. Breaking Down Sound | Sound waves have 3 physical dimensions – frequency (pitch) amplitude (loudness) & timbre (complexity) – that correspond to the perceptual dimensions

  • Pitch (Frequency) refers to the position of a sound on the musical scale as perceived by the listener. Pitch is very clearly related to frequency: the vibration rate of a sound wave. Let us take for example, middle C, described as a pattern of sound frequencies depicted in FIGURE M. The amplitude of the acoustical energy is conveyed by the darkness of the tracing in the spectrogram. The lowest component of this note is the fundamental frequency of the sound pattern, which is 264 Hz, or middle C. Frequencies above the fundamental frequency are known as overtones or partials. The overtones are generally simple multiples of the fundamental (for example, 2 x 264, or 528 Hz; 4 x 264, or 1056 Hz), as shown in FIGURE M. Overtones that are multiples of the fundamental freqency are known as harmonics.
  • Loudness (Amplitude) refers to the magnitude of a sensation as judged by a given person. Loudness, although related to the intensity of a sound as measured in decibels, is in fact a subjective evaluation described by simple terms such as « very loud », « soft », « very soft » and so forth.
  • Timbre (Complexity) refers to the individual and distinctive character of a sound, the quality that distinguishes it from all other sounds of similar pitch and loudness. For example, we can distinguish the sound of a guitar from that of a violin even thought they may play the same note at a similar loudness.
016 SpectrographicDisplay

FIGURE M. Spectrographic Display of the Steady-State Part of Middle C (264 Hz) Played on Piano | Bands of acoustical energy are present at the fundamental frequency, as well as at integer multiples of the fundamental (harmonics). (After Ritsma, 1967)

If the fundamental frequency is cancelled out from a note by the means of electronic filters, the overtones are sufficient to determine the pitch of the fundamental frequency – a phenomenon known as periodicity pitch.

The ability to determine pitch from the overtones alone is likely due to the fact that the difference between frequencies of various harmonics is equal to the fundamental frequency (for example, 792 Hz – 528 Hz = 264 Hz = the fundamental frequency). The auditory system can determine this difference, and hence one perceives the fundamental frequency.

One major aspect of pitch perception is that, although we can generate (and perceive) the fundamental frequency, we still perceive the complex tones of the harmonics, and this is known as the spectral pitch. When individual subjects are made to listen to complex sounds to then be asked to make judgements about the direction of shifts in pitch, some individuals base their judgement on the fundamental frequency and others on the spectral pitch. This difference from one to the other is not based or related to musical training but rather to a basic difference in temporal-lobe organisation. The primary auditory cortex of the right temporal lobe appears to make this periodicity-pitch discrimination.

1885 - 1886 - The Beginner (Margare Perry) y Elisabeth (Lilla) Cabot Perry (1848 - 1933)

1885 – 1886 – The Beginner (Margaret Perry) by Elisabeth (Lilla) Cabot Perry

Robert Zatorre (2001) found that patients with right temporal lobectomies that include the removal of primary auditory cortex (area 41 or Heschl’s gyrus) are impaired at making pitch discriminations when the fundamental frequency is absent but are normal at making such discriminations when the fundamental frequency is present, however their ability to identify the direction of the pitch change was impaired.

Timing is a critical component of good music, and two types of time relations are fundamental to the rhythm of musical sequences:

(i) The segmentation of sequences of pitches into groups based on the duration of the sounds

(ii) The identification of temporal regularity, or beat, which is also professionally known as meter.

Both of these two components could be dissociated by having the subjects tap a rhythm versus keeping time with the beat (such as the spontaneous tapping of the foot to a strong beat)

Robert Zatorre and Isabelle Peretz came to the conclusion after analysing studies of patients with  temporal-lobe injuries as well as neuroimaging studies, that the left temporal lobe plays a major role in temporal grouping for rhythm, while the right temporal lobe plays a complementary role in meter (beat). However, the researchers also observed that a motor component of rhythm is also present, and it is broadly distributed to include the supplementary motor cortex, premotor cortex, cerebellum, and basal ganglia.

RareDicesOfGodHawking

In seems clear that music is much more than the perception of pitch, rhythm, timbre and loudness. Zatorre and Peretz reviewed the many other features of music and the brain, including faculties such as music memory, emotion, performance (both singing and playing), music reading, and the effect of musical training. The importance of memory to music is inescapable since music unfolds over time for one to perceive a tune.

The retention of melodies is much more affected by injuries to the right temporal lobe, although injury to either temporal lobe impairs the learning of melodies. While both hemispheres contribute to the production of music, the role of the right temporal lobe appears to be greater in the production of melody, and the left temporal lobe appears to be mostly responsible for rhythm. Zatorre (2001) proposed that the right temporal lobe should have a special function in extracting pitch from sound, regardless of whether the sound is speech or music. However, when processing speech, the pitch (frequency) will contribute to the « tone » of the voice, and this is known as prosody.

Earlier, we learned from Kenji Tanaka’s studies of visual learning about how cells in the temporal lobe alter their perceptual function with experience [training]. Unsurprisingly, the same appears to be valid for musical experience. Zatorre and Peretz reviewed noninvasive imaging studies and concluded not only that the brains of professional musicians have more-pronounced responses to musical information than to those of non-musicians [or non musically oriented], but also that the brains of musicians have a completely different morphology in the area of Heschl’s gyrus. Peter Schneider and his colleagues estimated the volume of gray and white matter in Heschl’s gyrus and found much larger volumes in both temporal lobes in the musicians (see FIGURE N).

017 MusicandBrainMorphology.jpg

FIGURE N. Music and Brain Morphology | (A) At left, a three dimensional cross section through the head showing the primary auditory cortex (AC) in each hemisphere, with the location of auditory evoked potentials shown at red and blue markers. At right, reconstructed dorsal views of the right auditory cortical surface showing the difference in morphology among three people. Heschl’s gyrus is shown in red. (B) Examples from individual brains of musicians (top row) and non-musicians (bottom row) showing the difference in morphology between people who hear fundamental frequency and those who hear spectral pitch. Heschl’s gyrus is bigger on the left in the former group and bigger on the right in the latter group. Note: Heschl’s gyrus is bigger overall in the musicians. (From: Schneider, Sluming, Roberts, Scherg, Goebel, Specht, Dosch, Bleeck, Stippich and Rupp, 2005).

These gray matter differences are positively correlated with musical proficiency, i.e. the greater the gray-matter volume, the greater the musical ability. It has also been revealed that fundamental-pitch listeners exhibit a pronounced leftward asymmetry of gray-matter volume in Hechl’s gyrus, whereas spectral-pitch listeners have a rightward asymmetry, independent of musical training (see FIGURE N (B)). The results of these studies from Schneider imply that innate differences in brain morphology are related to the way in which pitch is processed and that some of the innate differences are related to musical ability. Practice and experience with music seem likely to be related to anatomical differences in the temporal cortex as well, however the relation may be difficult to demonstrate without brain measurements before and after intense training in music.

Although the role of the temporal lobes in music is vital [similar to language which is also distributed in the frontal lobe], music perception and performance also include the inferior frontal cortex in both hemispheres. Sluming et al. (2002) have demonstrated that professional orchestral musicians have significantly more gray matter in Broca’s area on the left. Such frontal-lobe effect may be related to similarities in aspects of expressive output in both language and music. The main point however, is that music likely has widespread effects on the brain’s morphology and function that science has only started to unravel.

018 NeanderthalBoneFlute

This bone flute found in Hohle Fels cave is believed to be around 43, 000 years old and comes as evidence that, like modern humans, Neanderthals likely had complementary hemispheric specialisation for music and language, which means that these abilities seem to have biological & evolutionary roots. While this assumption seems obvious for language, it comes as less obvious for music, which has often been perceived as an artifact of culture. However considerable evidence suggests that humans are born with a predisposition for music processing. Young infants display learning preferences for musical scales and are biased towards perceiving the regularity (such as harmonics) on which music is built. One of the strongest evidence for favouring the biological basis of music is that a surprising number of humans are tone deaf, a condition known as congenital amusia. It is believed that these amusic types of humans have an abnormality in their neural networks for music, and no amount of musical training leads to a cure. [Credit: Jensen / University of Tubingen]


Asymmetry of Temporal-Lobe Function

Epileptiform abnormalities have often been linked to sensitive temporal lobes, and the surgical removal of the abnormal temporal lobe tends to benefit patients suffering from epilepsy. These surgical cases have also allowed neuropsychologists to study the complementary specialisation of the right and left temporal lobes.

From a comparison of the effects of right and left temporal lobectomy by Brenda Milner and her colleagues, it has been revealed that specific memory defects vary depending on the side of the lesion. Deficits in non-verbal memory (e.g. faces) is associated to damage to the right temporal lobe, and deficits in verbal memory to the left temporal lobe.

In a similar sense, right temporal lesions would be associated with deficits in processing certain aspects of music, while left temporal lesions would be associated with deficits in processing speech sounds. However, much remains to be learnt and discovered regarding the relative roles of the left and right temporal lobes in social and affective behaviour. Right, but not left, temporal-lobe damage/lesions lead to impairments in the recognition of faces and facial expressions; so it seems fairly obvious that these two sides play different roles in social cognition. From experience, clinical cases suggest that left and right temporal lobe lesions have different effects on personality. Liegeois-Chauvel and colleagues studied musical processing in large groups of patients with temporal lobectomies, and confirmed that injury to right superior temporal gyrus impairs various aspects of processing necessary for the discrimination of melodies. Furthermore, a dissociation between the roles of the posterior and anterior regions of the superior temporal gyrus on different aspects of music processing suggest their relative localisation within the superior temporal gyrus.

Hence, it would be incorrect to assume that the removal of both temporal lobes merely doubles the symptoms of damage seen in unilateral temporal lobectomy. Bilateral temporal-lobe removal produces dramatic effects on both memory and affect that are orders of magnitude greater than those observed subsequent to unilateral lesions.

*****

References

  1. Fuster, J.M. & Jervey, J.P. (1982). Neuronal firing in the inferotemporal cortex of the monkey in a visual memory task. Journal of Neuroscience. 2, 361-375
  2. Kolb, B. and Whishaw, I. (2009). Fundamentals of human neuropsychology. NY: Worth Publishers
  3. Liegeois-Chauvel, C., Peretz, I., Babai, M., Laguitton, V., and Chauvel, P. (1998). Contribution of different cortical areas in the temporal lobes to music processing. Brain. 121, 1853-1867.
  4. Perrett, D. I., Harries, M. H., Benson, P. J., Chitty, A. J. & Mistlin, A. J. (1990). Retrieval of structure from rigid and biological motion: An analysis of the visual responses of neurones in the macaque temporal cortex. In A. Blake & T. Troscianko, Eds. AI and the Eye. New York: Wiley
  5. Tanaka, J. W. (2004). Object categorisation, expertise and neural plasticity. In M.S. Gazzaniga, Ed. The Cognitive Neurosciences III, 3rd ed. Cambridge, Mass.: MIT Press
  6. Tanaka, K. (1993). Neuronal Mechanism of object recognition. Science, 262, 685-688

 

Updated July, 2nd, 2017 | Danny J. D’Purb | DPURB.com

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