Divergent thinking and hemisphericity
This study investigated the relationship between divergent thinking, assessed by the Product Improvement and Unusual Uses tests of the Torrance Tests of Creative Thinking (1974), and hemisphericity. Hemisphericity, cerebral hemispheric dominance for language function, was assessed by a dichotic listening technique. Sex, age, hand preference, and verbal expression (assessed by a subtest of the Illinois Test of Psycholinguistic Abilities) were controlled. Subjects were selected at three age levels: four years, seven years, and ten years. For the four-year-old group, the findings indicated that a significant positive relationship existed between the fluency and flexibility scores on the Product Improvement task and right dominant subjects; while a significant negative relationship existed between the flexibility scores on the Unusual Uses test and right dominant subjects. In an effort to explain these contradictory findings, the low correlation between the flexibility scores on the Product Improvement and Unusual Uses tasks was noted and discussed in terms of the possibility that these two tests were not measuring the same construct.
The effect of hemisphericity on divergent thinking did not reach significance for any other age group. No meaningful interactions were found when the following independent variables were analyzed: sex x hemisphericity, age x hemisphericity, hand preference x hemisphericity, and verbal expression x hemisphericity.
When cerebral dominance was examined across the three age groups, there was an increase in mixed dominance with increasing age. This finding was discussed with regard to the physiological maturation of the corpus callosum which may contribute to interhemispheric communication. Further discussion acknowledged that with an increase in age and cognitive growth comes the ability to better use both cerebral hemispheres.
Several limitations were considered in the discussion of the results of this study. These included: insensitivity of tests, attentional factors, the role of memory in the dichotic listening task, technical limitations associated with equipment, and the paucity of previous research on which to build in the area of hemisphericity and its relationship to creativity.
It was concluded from the findings of this study that for preschool age subjects, there is a positive relationship between right hemispheric dominance for language and the fluency and flexibility scores on the Product Improvement Task. With regard to the development of hemisphericity, the findings of this study indicated a trend toward greater mixed dominance with increasing age.