Date of Degree
PhD (Doctor of Philosophy)
An attentional template based on a feature in visual working memory (VWM) can be used to bias attention toward feature-matching objects in the visual field. Attentional guidance based on a single feature is highly efficient and has been well characterized. It is debated, however, whether multiple features can be used to guide attention simultaneously. Some argue that only a single feature in VWM can be elevated to an “active” state and influence perceptual selection. To evaluate whether multiple features can guide attention simultaneously, eye movements were recorded while participants completed both traditional and gaze-contingent visual search tasks. Participants demonstrated guidance by multiple features by switching between relevant colors frequently and without delay. Furthermore, relevant objects of different colors actively competed for saccadic selection. These results provide compelling evidence that multiple attentional templates are able to guide selection simultaneously.
Although it was originally proposed that a feature in VWM could also be used to bias attention away from irrelevant items (“template for rejection”), the evidence thus far has been mixed. Some studies report that participants were faster to find a target item after being cued with a distractor feature, suggesting participants were using this feature to avoid matching items, while other studies report a cost and find that participants actually attended to cue-matching items even though they are irrelevant. The current work demonstrates that some evidence in support of feature-guided avoidance can be explained by spatially recoding the cued feature information. Furthermore, when shown a distractor color at the beginning of a trial, participants frequently fixated a matching object early in the trial, but avoided matching objects later in the trial. Other work has suggested that this initial attentional capture by a cue-matching object facilitates later avoidance, but the current data do not support a functional relationship of this nature. In sum, it may not be possible to implement an exclusionary template directly as feature-guided avoidance, but it may be possible to implement indirectly by converting the irrelevant feature information into relevant feature or spatial information.
attentional template, exclusionary template, eye movements, visual attention, visual search, visual working memory
xiv, 155 pages
Includes bibliographical references (pages 146-155).
Copyright 2016 Valerie M. Beck