Abstract
Popular models of overt and covert visual search focus on explaining search efficiency by visual guidance. Visual guidance integrates information from the target template and potential target stimuli to prioritize probable target locations for selective processing. That some searches are fast whereas other searches are slow is explained by the ability of the target to guide attention to the target's position. Comparably little attention is given to other variables that might also influence search efficiency, such as dwelling on distractors, skipping distractors, and revisiting distractors. Here we test the relative contributions of dwelling, skipping, rescanning, and the use of visual guidance, in explaining visual search times, and in particular the similarity effect. The similarity effect is the more efficient search for a target that is dissimilar from the distractors compared to a target that is similar to the distractors. In the present experiment, the experimental task is to find an emotional face target among nine neutral face non-targets. In different blocks, the target is either more or less similar to the non-targets. Eye-tracking is used to separately measure selection latency, dwelling on distractors, and skipping and revisiting of distractors. As expected, visual search times show a large similarity effect. Similarity also has strong effects on dwelling, skipping, and revisiting (but not on visual guidance). Regression analyses, conducted on both the condition and the trial level, further confirm these findings. Overall, results show that with complex stimuli like faces, target-distractor similarity influences search times primarily via the time gaze dwells on the non-targets and to a somewhat lesser degree by altering the proportion of revisited non-targets in the course of search. Measures of attentional guidance contributed relatively little to the similarity effect.
Meeting abstract presented at VSS 2017