Poster B32, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Evolutionary Purpose Of A Left-Lateralized Task-Switch Mechanism: Insight From A Novel Behavioral Procedure
Nicole M Bowlsby1, Barbara J Rutherford1; 1University of British Columbia Okanagan
Imaging of the neurologically intact suggests that neural circuitry to support task switches is lateralized to the left hemisphere. Behavioral consequences to the neurologically intact remain under-investigated. Further limiting understanding is that the few previous studies utilized procedures with task demands that were unnatural and inconsistent with imaging investigations. The current research uses a novel behavioral procedure with two goals: (1) address the gap of behavioral evidence; (2) facilitate understanding of brain-behavior relationships with a procedure that invokes task demands comparable to imaging. Three experiments present visual targets at fixation, and weight processing to one or other hemisphere by simultaneous presentation of a lateralized visual distractor. Two experiments present spatial or rhyme tasks in a valid cuing paradigm to establish baseline performance and lateralization under a condition of maximal predictability. The third experiment mixed the tasks and varied predictability by preceding targets with valid or invalid cues. Baseline tests found faster and more accurate responses to the spatial task, and left-lateralization of speed of spatial processing and rhyming accuracy. Mixed-task speed and accuracy converged to show stronger left-lateralization for rhyming. Notwithstanding differences in strength of lateralization, speed costs from invalid cues were symmetrical in each hemisphere for each task. In contrast, accuracy costs were not: Only the right hemisphere showed significant costs from invalid cuing, and costs were present regardless of task. The findings expand on imaging evidence to suggest that lateralization of the switch mechanism evolved in part to facilitate accuracy in a world of changing task demands.
Topic Area: EXECUTIVE PROCESSES: Goal maintenance & switching