Abstract
From searching for car keys to looking for the doorknob in a dimly lit room, visual search is a ubiquitous everyday decision task. Prior studies have demonstrated that while distributed attention is sufficient for detecting an oddball target among distractors, focused attention is required for discriminating a fine detail (e.g., cut-off side of a target). However, this difference in the spatial scope of visual attention allocation has been mainly investigated with only a single target among varying numbers of distractors. Yet, this single target search represents only a subset of real world visual search scenarios. For example, X-ray and baggage screening require visual search when multiple potential targets are present. Here, we examine whether the distinct scopes of attention observed in detection and discrimination tasks with one target continue to be involved when there are two potential targets. In each trial we randomly presented one or two color oddball targets along with five or four homogenous color distractors, respectively. Participants were required to detect or discriminate one oddball target even when there were two targets presented. We observed that increasing the number of targets lead to longer reactions time in the discrimination task but did not have much impact on detection performance. These results suggest that in accord with a single target task, distributed and focal attention is involved while detecting and discriminating among search displays with two targets, respectively.
Meeting abstract presented at VSS 2017