Multiple Object Tracking: Support for Hemispheric Independence
63.319, Wednesday, May 15, 8:30 am - 12:30 pm, Royal Ballroom 6-8
Daryl Wilson1, Michael O'Grady1, Jason Rajsic1; 1Psychology Department, Queen's University
Using a variant of the multiple object tracking paradigm, Alvarez and Cavanagh (2005) showed that as the task became more demanding, tracking performance was significantly more accurate when targets were distributed between the left and right hemifields compared to when they were presented within a single hemifield. Based on this result, they proposed a hemispheric independence capacity account suggesting that there are independent resources for tracking in each hemifield. In the current study, we tested an alternative distribution account which suggested that the spatial distribution of the tracked objects was the factor underlying their results. In sixteen conditions, we manipulated the distribution of the targets (vertical or horizontal), the positioning of the distribution (within one side, both sides central, or both sides peripheral), the motion of the targets (within- or cross-hemifield), and the number of tracked objects (2 or 4). While the distribution of objects had a small influence on tracking performance, the largest factor influencing tracking performance was whether all stimuli were presented within the same hemifield or not. In sum, the results were largely inconsistent with the distribution account and provided support for the hemispheric independence account.