ORCID
https://orcid.org/0000-0003-4592-6408
Date of Award
12-7-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Salient visual stimuli automatically capture attention, and can disrupt ongoing tasks when they appear as distractors. Recent research has found that with active inhibitory control, attention to salient distractors can be suppressed proactively. However, only under limited circumstances can active distractor suppression occur: the features of the distractor need to be known in advance. Distractors with unpredictable features cannot be ignored. In those previous studies, however, the target of the search task was also salient to an extent, which might have limited participants’ ability to ignore a salient distractor. Because distractions in everyday life are rarely predictable, to allow real-world implications in the study of suppression, my dissertation research aimed to revisit the possibility of suppressing salient unpredictable distractors when the task goal does not require attention to a salient target. In three experiments, the saliency of the target in a visual search task was separately reduced by increasing the physical resemblance, complexity, and common features of the search array stimuli. Experiment 1 used highly similar shapes for the target and the non-target items in a search array. Experiment 2 used complex stimuli as the array items in order to reduce the perceived uniqueness of individual items. Experiment 3 required a conjunction search, where the target shared all composing colors with the non-target items, but only differed in the arrangement of the colors. In all three experiments, the search array items were homogeneously in a single color, except when a color singleton distractor was present in a unique color. The color of the array elements and the singleton distractor unpredictably alternated throughout each experiment. My results showed that the color-unpredictable singleton distractor was not suppressed when target saliency was reduced, but it instead captured attention in all three experiments. This suggests that the representational ambiguity of the search target, or the efficiency of the visual search task, does not affect distractor suppression. Follow-up experiments also examined the effect of these methods on suppression of a color-known singleton distractor. While the distractor was suppressed, the strength of suppression was not affected by reduced target saliency. Together the results imply that the inhibitory mechanism underlying distractor suppression is not subject to the influence of the top-down target representation in classical visual search tasks, contrary to some previous beliefs.
Language
English (en)
Chair and Committee
Richard Abrams
Recommended Citation
Ma, Xiaojin, "Effects of Target Saliency on Inhibition of Salient Distractors" (2023). Arts & Sciences Electronic Theses and Dissertations. 3200.
https://openscholarship.wustl.edu/art_sci_etds/3200