Effects of Workload Division on Interhemispheric Processing in Complex Semantic Tasks: Evidence from Reaction Time Differences

An ongoing controversy over factors inducing the advantages of interhemispheric processing conveys complex neuronal interactions. The current study investigated how a division of workload between two hemispheres affects task performance in semantic processing. When task difficulty increases, interhemispheric processing enhances performance. Thirty-nine subjects participated in the experiment and performed three matching tasks with different difficulty levels, including physical identity, semantic basic-level, and semantic categorization. The first task required participants to respond if two of three words displayed physically identical appearance (e.g., BUS BUS). The difficult tasks demanded subjects to match when two of three words belong to the same category (e.g., BUS CAR) or one word belongs to its category (e.g., SKI SPORT). The researcher predicted dividing the workload between two hemispheres would aid performance for the more difficult semantic basic-level and categorization tasks while impeding performance for an easy task like physical identity. Among the participants, differences in task performance could not be attributable to a division of workload and levels of task difficulty. Besides, participants performed better in a difficult task (i.e., semantic basic-level matching) when an interhemispheric processing did not occur. The results allude to the left hemisphere’s competence in language processing. Further study of changes in semantic features and equipment tools is necessary to draw decisive conclusions about the effects of task difficulty on interhemispheric processing of semantic information.