Abstract
Looming motion has previously been shown to capture attention in a visual search task (Lin, Franconeri, & Enns, 2008); when targets loom toward an observer, search times are faster compared to when targets are static or distractors are looming. Although this finding has been replicated, there does appear to be an interesting caveat. More specifically, costs associated with looming distractors only seem to occur when object motion is smooth (compared to apparent) and that capture is rarely associated with an overt eye movement (Lewis & Neider, 2013). To determine whether the latter finding reflects covert attentional shifts or was a byproduct of peripherally discriminable search items, we ran two experiments in which we increased the difficulty of discriminating an oval target from distractor spheres, relative to our previous studies. Within each trial, a target (8% deformation from spheroid) or distractor could loom, or all items were static (control condition). In Experiment 1 motion was apparent and in Experiment 2 motion was smooth. Objects were presented centrally (5.5° from center) or peripherally (10.5° from center). In both experiments, there was an RT benefit for looming targets (~307 ms and ~230 ms for Experiments 1 and 2, respectively). Replicating our previous findings, looming distractors only induced an RT cost when motion was smooth (~96 ms). With harder targets, participants made a higher proportion of target fixations compared to our previous studies with easier targets (~85%). Participants fixated on looming distractors more when located centrally than in the periphery (~68% and 48%, respectively). When there was a looming distractor, participants fixated on more objects per trial compared to control trials. Overall, these results indicate that looming targets capture overt attentional shifts, but looming distractors do not always result in fixation capture.
Meeting abstract presented at VSS 2014