Sensory-motor infants, infants within in the Piaget first stage between birth and 2 years, gain mainly physical knowledge from “doing”. If infants can not see or touch an object they stop trying to find it. Once they develop the ability to recognise that a hidden object still continues to exist, they start searching for it. Ability to represent the object in their mind is a crucial step on the path towards what Piaget called abstract symbolic thought. This ability to think about an object seen previously, even if it is no longer present is a development from the achievements gained by assimilation and accommodation. However, again this development depends on the parallel development of the sensorimotor experiences of the infant. If this neurobiological development isn’t occurring then the infant’s cognitive development of abstract symbolic representation will be constrained. It also depends on whether or not the infant’s memory skills are developing. If this is not the case then being able to think about an object seen earlier when it is no longer present would not be possible. So it can be seen that neurobiological development can have a constraining effect on cognitive development if the two are not running parallel to one another.
Neurobiological development of a certain region in the prefrontal cortex, just in front of the motor projection area (Gleitman. H. 1999), constrains cognitive development of object permanence and the search process. This is concluded by looking at the A-not –B effect, where an infant will continue to search at the place where they previously found the toy instead of where they have seen it being placed. Having previously reached for A a few times this response is primed and although the infant appears to be aware of the move of the toy to a different location (evident by the fact that they look to location B when reaching for A) they are unable to override this recently primed reaction. So it seems that the infant has seen the move but not been able to transform this information to their motor response of reaching for the correct location. This it is suggested is down to the maturation of the prefrontal cortex, which is behind the cognitive development of the infant. The infant has to wait for the neurobiological development of this area of the brain to catch up before it can coordinate what it sees with what it does in response. These connections between the prefrontal cortex and the infant’s results in the A-not-B effect test have been shown in an experiment by Diamond, A. & Goldman-Rakic. Their work on rhesus monkeys with lesions reports evidence linking the dorsolateral prefrontal cortex with one of the cognitive abilities that emerges in infants between 7- 12 months of age (Diamond & Goldman-Rakic, 1989).
Our intelligence and cognitive development reflects the specific physical circumstances in which it develops (Thornton, S. 2002). The genetic blue print with which we are born is a necessary precondition for all development. We will never fly like birds or walk on water like some insects, no matter how much we practice. The Nativist approach to development argues that cognitive development is matter of maturation. Development is largely motivated by some form of physical maturation, a predetermined progression of growth that is based on neural changes. This physical maturation can be seen in the increase in brain size in the first months of infancy. This is due to the increase in synaptic connections in the cortex, a process which continues well into school years. So if the brain is getting more and more complex as dendritic growth and synapse formation progress it stands to reason that cognitive complexity would follow suit. However, it also stands to reason that cognitive complexity would be constrained by neural development as it would need to wait until the appropriate connections and so on to be formed.
Some other constraints on cognitive development are to do with the blue print with which the infant is born. The processes that guide development of the human brain are so various and complex, there are many ways in which they can go wrong (Rosenzweig, 2002). The many factors that control brain development, such as migration, differentiation and synapse formation, are subject to failures that can have profound effects on the cognitive development of the infant. For example, exposure to drugs or alcohol during the foetal stage results in 40% of exposed infants developing behavioural impairments. This is due to the abnormal development of the brain associated with Fetal Alcohol Syndrome and can include the lack of a corpus callosum connecting the two hemispheres. The lack of neurobiological development can have sever effects on the infant’s cognitive development, constraining its ability to form the necessary social skills to get on in life. This is also the case with some genetic disorders which also effect neurobiological development. For example, Down syndrome which results from a chromosomal abnormality. This results in abnormal formation of dendritic spines and behavioural dysfunctions.
So in conclusion it can be seen that neurobiological development can have a profound constraint on cognitive development reasons. If neurobiological development is not progressing alongside cognitive development then this can cause constraints as the cognitive development is dependent on the neurobiological. This was seen with the development of the infants object permanence and abstract symbolic thought formation. Cognitive development is an outcome of various factors not one that stands alone. Certain aspects seem to be driven by physical maturation and others through interaction with the environment through sensory-motor capabilities developed in the womb.
References!
Gleitman, H., Fridlund, A. J. & Reisberg, D. 1999. Psychology. (5th Ed) P533-572.
Diamond, A. &Goldman-Rakic, P. S. 1989. Comparison of human infants and rhesus monkeys on Piaget’s AB task: evidence for dependence on dorsolateral prefrontal cortex. Experimental Brain Research, 1989; 74; (1) 24-40
Rosenzweig, Breedlove & Leiman. 2002. Biological Psychology. (3rd Ed) P184-205
