Cognitive development

Ulric Neisser (1967): the term "cognition" refers to all processes by which the sensory input is transformed, reduced, elaborated, stored, recovered, and used.

Piaget's constructionist theory of cognitive development

• Concerned with the origins of knowledge: where does knowledge and thought come from? Piaget thought that studying development could provide the answers to this
• Development caused by interaction of heredity and environment: inheritance of certain ways of acting on the world which predispose the infant to acquire environmental input which in turn changes the ways in which they act on/think about the world
• Internally generated (active) processes construct cognition i.e assimilation and accommodation
• Stage-wise domain-general development: cognitive developments affect performance across multiple domains of knowledge

Piaget viewed intellectual growth as a process of adaptation to the world. This happens through:

• Assimilation: using an existing schema to deal with a new object or situation
• Accommodation: when the existing schema doesn't work and needs to be changed to deal with a new object/situation
• Equilibration: force which moves development along. Piaget believed that cognitive development didn't progress at a steady rate, but rather in leaps and bounds. Equilibrium occurs when a child's schemas can deal with most new information through assimilation. However, an unpleasant state of disequilibrium occurs when new information can't be fitted into existing schemas (assimilation). We seek to restore balance by mastering the new challenge (accommodation). Once the new information is acquired the process of assimilation with the new schema will continue until the next time we need to make an adjustment to it

Piaget's 4 stages of cognitive development: sensorimotor (birth - 2 years), pre-operational (2-7 years), concrete operational (7-11 years), formal operational stage (11+)

Piaget (1954) observed that 6 month olds show a striking neglect of objects once hidden. At 8 months, infants have some object permanence but struggle with the A B task: "suppose an object is hidden at point A: the child searches for it and finds it. Next the object is placed in B and is covered before the child's eyes; although the child has continued to watch the object and has seen it disappear in B, he nevertheless immediately tries to find it in A" - Piaget. However, the child will look at the B position while they uncover A.

Piaget argued that infants initially define hidden objects as existing in relation to their own action of retrieving them - still an egocentric understanding of objects. Piaget's methods largely depend on manual abilities. It may be that babies understand things about objects but just cannot/do not act on them.

Kellman & Spelke (1983) modified habituation: habituated 4-month-olds demonstrated to a partially occluded rod looking preference for a broken rod over a complete rod. Spelke uses this as evidence for innate understanding that common motion signifies that the object is unified behind the occluder. They exhibited preference for the broken rod which suggests they saw this as novel stimuli; they knew the rod was complete behind the occlusion. 

Spelke et al (1992): at 3 and 4 months of age, infants are not able to talk about objects, produce and understand object-directed gestures, locomote around objects, reach for and manipulate objects, or even see objects with high resolution. Nevertheless, such infants can represent an object that has left their view and make inferences about its occluded motion.

Challenge to Piaget: babies have an innate understanding of objects which is independent of action. Infants can think symbolically and logically about their environment without construction through action. Looking-time studies have more recently shown that infants appear to have knowledge of spatial layouts (Kaufman & Needham, 1999), number and maths (Wynn, 1992), and false belief (Onishi & Baillargeon, 2005).

But, if infants know that objects are permanent, why do they not retrieve them in manual tasks? Research by Hood, Carey & Prasada (2000) have shown that on some tasks, even 2 year olds appear ignorant of some of the principles which Spelke claims 2.5 month olds can reason about. 2.5 month olds understand solidity (shown through longer looking times at impossible events in which solidity is violated), but when 2 year olds are shown similar events and asked to search for the object, they disregard the solidity of the dividing surface.

Manual retrieval is constrained by the maturation of particular brain areas e.g frontal lobe maturation and executive function (Diamond, 1991).

In the A not B error, infants seem to demonstrate they do know where the correct place to search is as they will stare at the A position whilst lifting B. Diamond argued that infants know where the object is, but are unable to inhibit a habitual response (object knowledge, but no response inhibition).

Others have argued that you need different kinds of knowledge about objects to demonstrate understanding in looking time and reaching tasks. Looking behaviour demonstrates a type of knowledge which does not meet Piaget's more stringent criteria for object permanence.

Piaget described early and middle childhood as the period of concrete operations in which children develop their abilities to think about objects.

Preoperational: children prepare for concrete operations - they recapitulate everything they learned in the sensorimotor period, but in the realm of thought (rather than action) - egocentrism is still an important aspect of thought.

Concrete operational: children develop an ability to think logically about objects

Piaget considered the central development of the concrete operational stage to be "reversible thought": an ability to imagine the opposite of a perceived transformation. Reversibility enables children to understand what remains invariant (e.g when a row of counters is spread out, the number remains invariant, despite changes in length). Piaget argued that reversibility had influences across domains of knowledge. This attainment marked the transition between preoperational and concrete operational sub-periods.

Conservation: Piaget investigated children's understanding of "invariance" across transformations. In the task, children are shown two equal rows of counters, almost all can say both rows have same quantity. Children then watch a transformation of one of the rows (the counters are spread out) and asked if the rows contain the same quantity. Younger children will usually say no, but older children answer yes. Piaget concluded that young (pre-operational) children don't understand quantity. This conservation problem is found in volume too (matter and liquid).

Class inclusion: children shown line of beads which includes 4 yellow and 9 brown beads. Asked if there are more beads, or brown beads. Child usually answers that there are more brown beads; this is because they cannot simultaneously consider the subclass and inclusive class of beads without reversible thought.

Perspective taking: children were placed in fixed position in front of a 3D array and asked to imagine what it would look like from another side. 4-year olds typically pick their own view. Piaget argued this was due to an inability to reverse perceptual transformations

Margaret Donaldson argued that children don't understand the experimental situation in many of Piaget's tasks and may be mislead by the experimenter's actions and repeated questions.

McGarrigle & Donaldson (1974) tackled the complexity of the conservation task by introducing the "naughty teddy" - they assumed children may respond incorrectly in the counter task as they have seen the experimenter make the change, and it seems pertinent to respond differently in response to the repeated question. Thus, having the "naughty teddy" to make the transformation improved younger children's performance.

Peter Bryant argued that Piaget's research methods place unrealistic demands on children's memory. 

Bryant & Trabasso (1971) argued that the main problem for children in Piaget's task was in remembering the premises (in the transitivity task children shown bars A>B and B>C, could not infer difference between A and C after being shown these premises). When children were trained to remember the premises before they made the inference, children in the preoperational period could pass easily.

Key points

• Concerned with the development of cognitive processes (memory, attention, etc.) - how does memory/attention etc develop and how does this impact on performance across a range of tasks
• More agnostic about the causes of development - some theorists advocate the role of environmental input, but many appeal to maturational improvement. Generally more compatible with a nativist position on the development of knowledge
• Some argue that changes in capacity limitations are the most important, others point to the development of cognitive complexity and strategies
• Quibble with Piaget on the nature of the stages

Improvements in short-term memory capacity with age: phonological memory, visuospatial memory, and complex working memory are all shown to improve with age (Gathercole, 1999)

5-year old can manage to store around ~4 items in short-term memory, 12-year olds ~6-7 items, and adults ~8 items. Reduced short-term memory has implications on a wide range of abilities: reading, maths, etc.

Even though children's phonological short-term span changes, a large factor in this is motivation to remember - they are better when the task interests them (Dempster, 1985). Short-term visual memory capacity is adult-like by the end of the first year of life (Ross-Sheehy, Oaks, & Luck, 2003)

An important factor in short-term memory is use of processing strategies such as rehearsal. Ability to rehearse is a better predictor of short-term memory performance than age. This kind of observation brought the working memory model (which emphasises processing strategies) to the forefront in explaining development.

Executive function is a term used to describe how we organise our knowledge so that it can be deployed usefully; it is central to our use of cognitive strategies. Prefrontal cortex is strongly implicated in these functions. It groups several kinds of mental phenomena:

• working memory
• attention shifting
• problem solving
• planning
• inhibition

Classic executive functions task in infancy is the cloth-pulling task (Willatts, 1999). Infants are presented with an object which they can only retrieve by an intermediary action (pulling it towards them on a supporting cloth). 7 month olds would retrieve the object without watching it during their response. 8 month olds demonstrated intentional means-end behaviour - looking at their 'goal' when pulling the 'means'. A successful intentional response required executive functions: holding the goal in mind, inhibiting response to goal, and planning a sequence of actions.

Manual retrieval of hidden objects requires means-end coordination. Piaget invokes knowledge (object permanence) whereas others argue that working memory and inhibition are important (e.g Diamond, 1990).

In the AB error Diamond observed that infants looked in the correct place, but searched manually in the wrong place. He argued that infants know where the object is but are unable to inhibit a habitual response (object knowledge, but no response inhibition). Information processing approaches are well-matched with nativist accounts of cognitive development (knowledge is there, but we have to wait for the executive processes to mature).

There are lots of advances in executive function beyond infancy and right through to childhood. Two tasks used in early childhood are: the reverse contingency task or dimension change card sort (Zelazo et al, 1996)

Windows task (Russell et al, 1991)

• Prize is hidden in one of two opaque boxes and the child chooses a box for the experimenter by pointing at it
• Whoever finds the treat wins - teaches the child that the other person will get whatever they point at
• Windows are then put in the boxes so the child can see where the prize is. 4 year olds succeed and point away from it. 3 year olds perform exceptionally poorly pointing at the prize they want. Difficulty with inhibiting goal response

Dimension change card sort task (Zelazo, Frye & Rapus, 1996) developed the DCCS to test executive function (cognitive control) in 3 and 4 year olds

• Children asked to sort a stack of blue stars and red faces either by colour or shape. Halfway through the game the rules changes
• Despite answering correctly to questions concerning the games rules, at 3 years children typically continue sorting cards with respect to the first dimension even if the rules have changed

Children can demonstrate more competence early on with executive tasks involving control of more implicit knowledge rather than explicit rules.

Bremner et al (2007) used an incidental learning method to train 2 year olds on a sequence of movements and then asked them to repeat that sequence or generate a new sequence. 2 year olds were able to do this. Difficulties may be with executive control of explicit rules rather than control or inhibition per se.

Maturational: changes in simple capacity-like processes like inhibition and short-term memory duration. Appealingly simple and might be particularly important in infancy

Conceptual: appeal to changes in the way children think about problems. More complicated and probably accounts for more of the data in childhood

Developmentalists have tended to overlook the effect of the social context on cognitive development. Social context is primarily concerned with how children come to understand the logical and physical properties of the physical world.

Doise et al (1975): found that 6-7 year olds working together performed better than they had done individually (on spatial and liquid conservation tasks). Each child gave individually appropriate explanations at post test.

Light (1994) showed that 11 year old children who had worked together jointly on session 1 and 2 performed better than those who worked individually in session 3. Effect of peer interaction has been shown in other Piagetian tasks, with older children and adolescents.

Ames & Murray (1982): non-conserving children can learn from peer interaction with other non-conservers - pre-test 6-7 year old children selected who failed conservation of volume and length tasks. They were either paired with peers who also failed, but gave different answers(1), given correct model answers(2), or corrected feedback(3). Only children in condition 1 showed a marked gain in performance at immediate and delayed post-tests.

Doise & Mugny (1984): conflicting opinion will not inevitably lead to cognitive gain. The capacity of a child to learn is constrained by what they already know. It requires a small gap between child's previous understanding and the new ideas to work.

There is controversy about the exact features of social interaction that promote cognitive development. The debate concerns the relative importance of external and internal processes. Some contend that children learn from social interaction through the internalisation of correct answers (imitation). Bijstra (1991) found intermediate conservers gained from peer interaction. However, it was the presence of the correct answer rather than conflict resolution that causes development and cognitive gain.

Others contend that the presence of the correct answer during the peer interaction is irrelevant. The existence of sociocognitive conflict rather than the quality of the ideas is important.

Howe (1990-1992): most successful groups of children were those where the peers initially had different ideas. Both peers showed gains, even the more advanced peer improved.

"The entire history of the child's psychological development shows us that, from the very first days of development, its adaptation to the environment is achieved through social means, through people surrounding it" (Vygotsky & Luria).

Vygotsky's emphasis on the social origins of human development fitted with some of the critiques of Piagetian theory and discontent with the cognitivist approach.

Piaget viewed a child's cognitive development as "a manifestation of the child's largely unassisted activities" (Wood, 1988). Vygotsky (1978) saw social or sign mediation as central to human development. The "simple stimulus-response process is replaced by a complex mediated act".

The child acquires patterns of social interaction (which become internalised) that are moulded in the form of tangible objects or sign systems. Leontiev: e.g of baby feeding with a spoon. Infant handles a spoon as they would any natural object. Handling slowly, but radically, becomes reorganised by adult intervention to conform to specific social use. Not merely learning the physical properties, but mastering the social modes of acting with those things

Early sign operations in children (Leontiev (1932): answer a set of questions without using certain colour words. Task 1 = no rules. Task 2 = 2 forbidden colours + no repetition. Task 3 = same rules as 2 but given 9 coloured cards as aids to playing the game. 5-6 year olds showed little improvement between 2 and 3. 8-13 year olds showed sharpest drop in errors between 2 and 3.

In school-age children we see a rapid development of sign operation or mediated thinking. 3 basic stages in the development of mediated remembering

• Pre-school children are not capable of mastering their behaviour by organising special stimuli. Coloured cards are of little help
• Introduction of cards as a system of auxiliary, external stimuli raises the effectiveness of school-age children. The auxiliary stimulus is a psychological instrument acting from the outside
• Auxiliary stimuli are emancipated and the sign becomes internalised within the child's mind

Zone of proximal development (ZPD): developed by Vgotsky - it is the difference between what a learner can do without help, and what they can't do. Vygotsky stated that a child follows an adult's example and gradually develops the ability to do certain tasks without help. Vygotsky believed that the role of education is to give children experiences that are within their zones of proximal development, thereby encouraging and advancing their individual learning such as skills and strategies. Vygotsky used the ZPD as a conceptual tool to capture the relationship between the social and individual levels of functioning.

Rutland & Campbell (1996): ZPD scores for all phases of testing correlated significantly with IQ. Addition of ZPD scores increased variance explained by 31% to 51%.

Education should not follow the lead of development (Piaget 'ready'), but education should aim at the leading edge of the child's ZPD, so engaging the child in socially mediated activity which ultimately leads to internalisation.

Young children often talk in monologues to themselves when engaged in activity. Piaget argued that this was a sign of a children's egocentrism. Language development as an outcome of cognitive development - language as an add-on. Piaget explained that as language develops, children lose private speech - it is an indicator of poorly-developed speech.

Vgotsky argued that these monologues perform the function of regulating action. The child solves a practical task with the help of not only eyes and hands, but also speech (Vygotsky & Luria, 1993). External speech as the beginning of the internalisation process leads to inner speech (dialogue with ourselves). External speech is still possible if the task is very hard.

For Piaget, language is a 'by-product' of cognitive development. For Vygotsky, language is central to the structuring and development of thought.

Berk (1994): longitudinal study in which children were observed while doing math work at their desks in the classroom. Private speech moved from external to more internal forms from ages 7-10. children with greater private speak tended to have higher maths achievement scores a year later, suggesting private speech facilitates learning.

Limitations in inner speech may account for the well-established executive impairments in autism spectrum disorder (Hill, 2004).

Russell-Smith et al (2014): performed a computer-based sorting test (CST, Heaton, 1993) to assess cognitive flexibility under 4 conditions: (1) baseline, (2) articulatory suppression - repeatedly verbalise the word 'Monday' in time with a metronome, (3) concurrent mouthing task - open and close mouth throughout, (4) verbalising their strategies aloud. ASD children do not use inner speech to the same extent, or with the same effectiveness as typically developing children when performing executive tasks.

Criticisms of Vygotsky

• Notion of internalisation and cognitive reconstruction is under specified. What structures or mechanisms mediating between the social and individual levels?
• Not possible to empirically prove Vygotsky's general genetic law of cultural development, since through the process of internalisation collective mental representations are transformed to different individual representations
• Vygotsky's main objective was to recontruct the general principles of developmental psychology, on the basis of fresh presuppositions. He died young, leaving others to properly flesh out his work

Jerome Bruner developed Vygotsky's ideas to expand on the mechanisms by which others can help development. He pioneered the idea of scaffolding - other people helping a child developing skills. It involves helpful, structured interaction between an adult and child, with the aim of helping the child achieve a specific goal

Vocabulary spurt: first words are often spoken around the first birthday. Babies typically have around 10 words or so by 18 months, but by 2 years of age children are learning an average of 1 new word every waking hour.

We need language for communication and maintenance of social groups/bonding. Researchers have argued that our brains are evolved to cope with the social groups we exist in. Dunbar (1993) shows that the average social group size of primate species holds a very strong relationship to brain size.

Language is typically divided into:

• Phonology: speech sounds and the rules by which they're combined; phonemes are the smallest units of sound which affect meaning
• Pragmatics: what to say and when to say it (politness, relevance etc)
• Grammar: the ways in which words and sentences are formed from smaller units of meaning. Morhpology concerns the make-up of words, and syntax concerns sentence structure.

Children can understand around 100 words at 18 months, but can typically only produce about 10. We know about comprehension from parental reports, but also studies in which babies' looking behaviour is observed whilst objects are being named. Children certainly pay attention to language well before they can speak it.

Speech sound discrimination is often measured using a preferential head turn procedure. The infant is trained to expect a visual reward when speech sounds change. Researchers can then probe whether speech sounds are differentiated by looking for an anticipatory head turn response. There's evidence that infants can distinguish many phonemes by 1 and 2 months of age (Eimas et al, 1971). 

Werker & Tees (1984) showed that phoneme discrimination is prominent at 6 months of age, but by 12 months babies lose the ability to discriminate speech sounds not differentiated in their native tongue.

Quine (1960): points out the difficulty of learning words via his idea of the "inscrutability of reference". When people refer to objects, how do we know what aspect of an object they're referring to? Markman (1989) proposed that infants use "word learning" assumptions to get around this problem

• the whole object assumption: that labels refer to the whole object
• mutual exclusivity assumption: that objects only have one name

Hollich et al (2007): taught infants the names of novel objects which could be disassembled into parts. At a test, 12 month olds preferred to look at the whole object than either of its parts when it was named subsequently. Strong evidence for the whole object assumption.

• Pre-linguistic: crying, cooing, babbling
• Holophrastic stage (12-18 months): one word utterances used effectively in combination with gestures
• Two-word stage (18-24 months): two word sentences
• Telegraphic stage (24-36 months): 3 or more word sentences
• Post-telegraphic stage (36+ months): complex combinations

Behaviourist account (Skinner, 1954): argued that parents selectively reinforce the infants' speech sounds which are most appropriate in a given context. Language is acquired through imitation (modelling) and reinforcement (positive and negative). Correct utterances are positively reinforced, enhancing the child's language development

Nativist (Chomsky): humans have an inbuilt capacity to acquire language through the Language Acquisition Device (LAD). The LAD is a language organ that is hardwired into our brains at birth, and because of this, we're born with the ability to understand and develop language (and especially grammar). Chomsky argues there are universal aspects of language which must be a result of a human biological preparation for language acquisition

Cognitive (Piaget): language acquisition is part of a wider development of understanding. Language is dependent on knowledge and understanding that is acquired through cognitive development

English-speaking children have to learn both regular and irregular forms of the past tense

• Regular morhpology (90% of verbs): talk -> talked, ram -> rammed, pit -> pitted
• Irregular morphology (10% of verbs): hit -> hit, come -> came, sleep -> slept, go -> went

Initially, children's early inflections are correct.

Dual-route model (Pinker & Prince, 1988): innate "rule" route deals with regular verbs. Exceptions route (learned) deals with irregulars. Errors in the middle of development occur due to overuse of the "rule system".