Concept usage in schizophrenic children.

This study compares concept usage and categorizing behavior among schizophrenic, normal, and brain-damaged children. Two sets of tasks were administered to each subject, the child being required to match an index object with one of a group of three choice objects. On the first task, the choice objects were related to the index object by class, function, or stimulus similarity; on the second task, the two choice objects were unrelated to the index object, while the remaining choice object was related by class or function. For both tasks the subjects were asked to state which of the choice objects was related to the index object, and why. Results indicated that the schizophrenic, normal, and brain-damaged children showed a significant improvement with increased age in utilizing class or function concepts. However, the schizophrenics, unlike the normal and brain-damaged children, did not benefit consistently from a reduction in stimulus competition. Within the schizophrenics, grouping by IQ revealed a dichotomous type of concept usage. Low IQ patients performed like the brain-damaged group; high IQ children failed to benefit from reduction in stimulus competition and produced more bizarre and irrelevant responses.