Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Michael O'Boyle


The purpose of the current research was to study the interhemispheric interaction in the brains of mathematically gifted youth, average ability adolescents, and college students. This study investigated the efficiency of interhemispheric interaction via the corpus callosum for brief displays of hierarchical stimuli under these conditions: (1) when both hemispheres have direct access to the visual information for performing global/local matches (i.e., bilateral redundant trials), (2) when the information necessary to perform such matches is divided between the visual-fields/hemispheres, thus forcing the hemispheres to exchange information to successfully perform the task (i.e., bilateral cooperative trials), and (3) when only one hemisphere has initial access to the information to perform global/local matches (i.e., unilateral trials). The college students produced the prototypical results with the right hemisphere (RH) superior for global processing and the left hemisphere (LH) for local processing. In addition, for college students, the LH showed aspects of metacontrol when information necessary to perform global/local matches was redundantly available to both hemispheres, whereas the RH showed metacontrol when the information necessary to perform global/local matches was split between the hemispheres. The average ability adolescents showed the prototypical results for local processing (i.e., LH faster for local processing), but showed no difference between the hemispheres for global processing. The mathematically gifted participants did not produce any reliable differences between hemispheres when processing hierarchical stimuli, which is consistent with previously obtained results showing bilateral involvement of the hemispheres in the gifted during basic information processing. Interestingly, average ability adolescents and college students exhibited considerable slowing and a greater number of errors in the cooperative viewing condition, while mathematically gifted adolescents were significantly faster and more accurate when the stimuli were divided between the visual-field/hemispheres suggesting enhanced interhemispheric cooperation as a unique functional characteristic of the mathematically gifted brain. Possible explanations for the pattern of performance by gifted individuals during the cooperative condition are examined (e.g., greater callosal connectivity in the gifted brain) and potential goals for future research with gifted participants are discussed.



Digital Repository @ Iowa State University,

Copyright Owner

Harnam Singh



Proquest ID


File Format


File Size

104 pages