Abstract
Many visual tasks seem to require that we split our ‘spotlight’ of selection across multiple objects. When objects move, maintaining selection requires that each region of selection track the object in a corresponding way, an ability typically studied using "Multiple Object Tracking" tasks. We recently advanced an account of MOT performance where performance limits in moving displays can be traced back to resource limits common between both moving and static displays. These limits, including object crowding and surround suppression, are both worsened by tighter object spacing. In contrast, others have argued that there must be additional processing resources specific to moving displays, because moving objects at faster speeds decreases the number of objects than can be tracked. Such results point to a draw on some other global tracking ‘resource’ within moving displays and imply a more complex architecture underlying MOT. We argue that these results can be explained by the limit of object spacing - faster objects experience more instances of tighter object spacing, which lowers performance. We control for this confound by playing tracking animations in either ‘slow motion’ or ‘fast forward’, keeping the distribution of object spacing identical, while drastically changing object speed. The data show that while increased object speed impairs performance, and tracking more targets impairs performance, these factors do not interact, showing that these impairments are not due to a shared processing resource. Experiment 1 demonstrates this effect using ‘random repulsion’ style displays, and Experiment 2 uses ‘orbiting moon’ displays. We argue that performance limits in MOT tasks can be parsimoniously explained by competition for limited representational space within a map of the visual field.
Meeting abstract presented at VSS 2012