Comparative study of the cognitive development of the infant with down's syndrome
Morss, John R.
This thesis investigates the cognitive development of the mentally handicapped infant in comparison with that of the normal infant. It has been claimed that the course of cognitive development in the infant with Down's Syndrome ('mongolism') can be explained as a 'slowed down' version of the development exhibited by the normal infant (as described by Piaget and others). In this thesis criticism is made of this 'slow development' theory. It is argued that such a formulation can, at best, offer a description of certain differences in developmental outcome (namely the delayed emergence of critical achievements on the part of the Dawn's Syndrome infant). It cannot explain why such differences occur. The necessity for analysis to proceed beyond a level of 'first emergence' is demonstrated by the findings of a comparative longitudinal study of cognitive development in the Down's Syndrome and the normal infant. It is shown that the nature of both success and failure on tasks relating to cognitive development is different between the two populations. It is argued that such differences must be seen as more fundamental than delays in outcome, and that an adequate explanatory model must therefore concern itself with the former. A theoretical account is presented which focuses attention on the manner in which competence is acquired, rather than on the formal properties of such competence. It is argued that for the Down's Syndrome infant, in contrast to the normal infant, acquisition and change cannot be posited to take place with respect to high levels of organisation of response. On the basis of this account, a prediction is derived concerning the efficacy of techniques designed to enhance the performance of the Down's Syndrome infant. Evidence is presented to show that enhancement can occur if appropriate restructuring of task presentation is made. It is also demonstrated that such enhancement is not exhibited by formally matched younger normal infants, under the same conditions. This finding confirms the view that the cognitive development of the Down's Syndrome infant must be seen as different from the normal, rather than merely 'slower'. General implications for both the normal and the handicapped infant are discussed. With respect to the latter, particular attention is paid to the role of deliberate intervention in early development.