Abstract
Introduction. Features that support “pop out” in visual search are often assumed to be associated with preattentive mechanisms that can support feature-based attention in other tasks. We have found that this assumption holds for luminance and hue; however, a companion presentation shows that, although differences in absolute bar-orientation support pop out, this feature dimension apparently does not support top-down, selective attention in a centroid task that requires integration of information from multiple targets. Disk size has been previously shown to enable pop out in visual search (Stuart, 1993). Here we examine whether top-down attention to disc size is possible in an information-integration task. Methods. Stimuli were briefly presented random clusters comprising 1-, 2-, 3-, or 4-each of equiluminant small-green, small-red, large-green, and large-red discs. In four different attention conditions, participants strove to mouse-click the centroid of only the (1) small, (2) large, (3) red, or (4) green discs in the stimulus display, ignoring the discs with the opposite feature. Performance was characterized in terms of the selectivity and efficiency of the attentional “filter” deployed in each condition. Results. Within each condition, both selectivity and efficiency declined slightly as the number of discs increased. Although the filters for size may have been slightly less effective than those for color, the numerosity effects were identical across conditions. Conclusion. Like luminance and hue, but unlike orientation, disc size supports top-down, selective attention in a task that requires integration of information from multiple targets such as the centroid task.
Meeting abstract presented at VSS 2015