No attentional capture for simple visual search: evidence for a dual-route account.

An enduring question in visual attention research is whether unattended objects are subject to perceptual processing. The traditional view suggests that, whereas focal attention is required for the processing of complex features or for individuating objects, it is not required for detecting basic features. However, other models suggest that detecting basic features may be no different from object identification and also require focal attention. In the present study, we approach this problem by measuring the effect of attentional capture in simple and compound visual search tasks. To make sure measurements did not reflect strategic components of the tasks, we measured accuracy with brief displays. Results show that attentional capture influenced only compound but not basic feature searches, suggestive of a distinction between attentional requirements of the 2 tasks. We discuss our findings, together with recent results of top-down word cue effects and dimension-specific intertrial effects, in terms of the dual-route account for visual search, which suggests that the task that is being completed determines whether search is based on attentive or preattentive mechanisms.