A longitudinal study of developmental changes in children's problem-solving strategies between 3 and 9 years
Previous studies of children's use of problem-solving strategies have been cross-sectional, and narrowly defined. These have described age-related development across a wide range of cognitive competencies. Parallel with this child development literature, studies in both humans and animals have linked active reduction of error in problem-solving to inhibitory function of a mature and intact hippocampus, and also to the frontal lobes. The present study was designed to investigate the development of availability and use of strategies by children in problem-solving tasks, and whether development of inhibitory ability is the underlying and enabling process for this. 96 children aged 3 years (N=32), 5 years CN=32), and 7 years (N=32), fully representative of sex and socioeconomic status, were each given a battery of six experimental tasks, (Wisconsin Card Sorting Test, Spontaneous Alternation, Oddity Problem, Two-Choice Discrimination Learning, Three-Choice Discrimination Learning and Attributes Task) on four separate, equal interval testing occasions over two years. Pre-tests of non-verbal intelligence, verbal comprehension and conceptual tempo were administered, prior to the first testing. The tasks were selected, following pilot study, to elicit behavioural evidence of problem-solving strategies, which might be dominant at different ages. Strategy was defined as a reflection of hypothesis forming and testing in a problem for solution. The results show age-related changes in the use of perseveration and alternation strategies, with indications of more complex strategies available to the 7 year old group. Strategies, once available, were differentially used in tasks within a testing, and appear to be linked to the cognitive demand of a task. In discussion, it is argued that the results from the use of the longitudinal design support a concept that a further functional system of inhibitory ability is developing from about 4 years of age. Both the hippocampus and frontal lobes appear to be implicated in this system which is seen as the process underlying the development of planning ability and active reduction of error. It is finally concluded that the emergent system of inhibitory ability is not unitary, but an elaboration of earlier abilities. This is reflected by the changes observed in availability and use by children of strategies for problem-solving. The development of their repertoire thus appears to be by the addition of new strategies, and their elaboration.