Cognitive development

One of the major aspects of development that exercises parents and teachers alike is how best to improve the intellectual functioning of children, be that in language, reading, memory, or general intelligence. To what extent individual differences in these areas are predominantly related to heredity or to environment continues to be a popular, if sterile, source of argument. Clearly, the end result comes from an interaction between genetic predisposition and experience, but there remain issues of how best to manipulate the environment so as to help children gain their maximum potential. To that end, an understanding of modern behavioural genetics is essential (see Ch§ipter,,2:4..1 and Chapter,2.4.2). Here, some of the methodological issues involved in assessing babies' cognitive processes and findings in cognitive development, language, and memory are considered.

Getting inside the baby's head

Until babies start to speak, it is difficult to know what they are thinking. Fond parents interpret wind-driven grimaces as smiling; every child is seen as recognizing people and being smart from a young age. But how can one tell what really goes on inside a baby's head?

Fantz(35) developed an experimental method based on earlier work with chicks. Soon after hatching, chicks start pecking at things to eat. Presented with a variety of different-shaped objects, chicks preferred round to angular objects, and solid rather than two-dimensional objects. These preferences emerged even in chicks deprived of early experience, and so this innate preference was seen as having survival value as round solid objects the size of seeds are most likely to be edible.

Fantz decided to look at infants' eye movements and use fixation time as a measure of preference for different stimuli. Film recordings were made of light reflected off the baby's eyes. In a study of 30 infants tested weekly from 1 to 15 weeks of age, it was shown that the infants spent longer looking at complex than simple patterns. This demonstration of a clear perceptual preference in the first few weeks after birth gave the lie to the view that all begins as a 'big booming confusion'. Infants as young as 1 week show clear preference for human faces over other shapes presented to them some 10 inches (25 cm) away.

Fantz took advantage of the technology of the day. Since then, others have utilized measures of changes in temperature, galvanic skin response, and heartbeat to provide behavioural indices of preferences. In addition, not only have crude indices of time spent gazing at an object been utilized, but also investigators have used various indices from learning and conditioning paradigms. Shaffer and Parry (36) compared the performance of 6-month-old and 12-month-old children on a test where novel stimuli were presented within their reach. For the first seven presentations, the same 'nonsense' object was presented and both groups of children rapidly lost interest (or habituated). When a novel toy was shown on the eighth trial, both groups showed renewed interest, but only the older children were able to act on the information and be cautious in reaching out for the toy. One explanation of this finding is that knowledge and action are out of step in the second half of the first year. Visual recognition exerts no control over behaviour. But by 12 months, the infant can act on the information. This ability to tell known from unknown, to tell friend from foe, but also to be able to take appropriate action has obvious survival value.

Similar studies have shown that new-born babies recognize their mothers' voices, and also recognize the signature tunes of 'soap operas' that the mothers watched during the latter stages of pregnancy! Fagan(37) tested visual preference in 7-month-old babies and later measured their intelligence when they were 3 and 5 years old. The time spent looking at the novel stimulus when a baby had a correlation of 0.42 with performance on the later Picture Vocabulary Test. Thus it is becoming easier to measure various indices of baby's reactions, and some of these are found to be usefully predictive of later development and adjustment.

Piaget and cognitive development

Piaget was a biologist who studied amoebas in his doctoral research. Biological models found useful for that purpose clearly influenced the way he regarded cognitive development. He held to a sort of moving homeostasis—children develop a model of the world. New information that challenges that model is gradually assimilated and eventually the model accommodates the new ways of thinking—somewhat similar to an amoeba reaching out to a piece of food, surrounding it, and assimilating it.

According to his theory, children pass through three broad stages of thinking (see Box,1): a sensorimotor stage, a long stage where they think in terms of what he called concrete operations, and finally a stage where they can think logically.

Piaget's stage theory has been very influential, and helpfully sparked off a great deal of research which has led to a much better understanding of how children develop cognitively. However, his original models were somewhat simplistic, and to have seen only three major stages covering a period of such rapid development appears to be inadequate. Moreover, for the clinician, the question one often wants to raise is how this understanding can be used to bolster the reasoning of a child who is developmentally delayed—what Piaget witheringly dismissed as 'the American question'. Piaget tended to argue that children could not be hurried through the stages. However, critics soon argued that some of the regularities that were apparently replicated in his work owed more to the manner in which the tasks were presented to the child than to any necessary underlying cohesion in types of thinking.

A typical experiment is to give a child two pieces of clay that are identical. Then one is rolled out into a sausage and the child is asked if they remain the same. Alternatively, the child is shown two test tubes of differing diameters. The same amount of liquid is poured into each but, of course, reaches different heights. Which test tube has more liquid? Not surprisingly, younger children make more errors than older ones, and it has been shown that an understanding of conservation of mass (seeing that the quantity of material remains the same despite of changes in shape) is acquired around 7 to 8 years, while conservation of weight is not understood until 9 or 10 years. It is not until the age of 11 or 12 that the child typically thinks that each shape also occupies the same amount of space (i.e. understands conservation of volume).

Pregnancy And Childbirth

Pregnancy And Childbirth

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