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Capacity constraints on reasoning : developmental aspects Pachev, Gueorgui Stefanov


The development of children's reasoning has often been associated with the attainment of strategies, higher-order concepts, or a broader knowledge-base. Several researchers have argued that these achievements are parallelled and influenced by a child's capacity to process a fixed amount of information in the context of a reasoning task. It is assumed that children's processing resources increase with age and that this increase allows children to acquire the more complex forms of reasoning, advanced strategies, etc. Insufficient resources, on the other hand, prevent children from performing at a higher level. The present study had two goals: (1) to provide evidence for the increase of resources with age, and (2) to explore the effects asociated with the limited-capacity of the processes involved in reasoning. Two dual-task paradigms were combined in the pursuit of these goals. One paradigm allowed for identifying the level of a task, at which performance was capacity-limited. Age-groups with different amount of resources were expected to exhibit capacity-limited performance at different task-levels. The second approach, based on introducing additional processing load, allowed for comparing the effects of charging the Capacity-limits of different processes involved in reasoning. Eighty-six children from three age-groups were given a matrices-completion task at four levels of difficulty. The task was performed either alone or concurrently with a second task. The secondary task was administered in the beginning or in the middle of some trials, thus disrupting processes at the initial stage and processes at the executive part of the solution. Capacity-limited performance was detected at the third and fourth level of the task for the first two age-groups, respectively. There was an indication that the oldest subjects would exhibit capacity-limited performance at levels beyond the fourth one. Reasoning performance deteriorated when the secondary task disrupted the operation of the executive processes. The additional load introduced in the beginning of a trial, however, did not affect the level of reasoning performance or resulted in improvement in certain conditions. The results were interpreted as supporting the hypothesis that the capacity factor operates as a necessary but not a sufficient condition for the development of reasoning.

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