UC Riverside

The human mind can ‘see’ visual objects without directly perceiving them through mental imagery. This ability represents objects in the mind to elicit visual experiences similar to those from perception. If imagery and perception represents objects in similar forms, then the effects of perception on subsequent processes should be similar to those of imagery. For example, a typical search task requires observers to bring to mind the target object to guide attention and increase search efficiency. However, whether imagery is deployed during search often is assumed and not empirically tested for. Imagery skills also widely vary across individuals based on how vividly their imagery appears to them, but how this variation impacts search is poorly understood. Across four studies, I investigated the use of mental imagery as an explicit strategy in search tasks. I hypothesized that imagery functions as a top-down process that mediates attentional processes and behavior. In Study 1, I present a series of visual search experiments with EEG that examined search efficiency (reaction time; the N2pc ERP components as a marker for attentional selection) following imagery. In Study 2, I present another series of EEG experiments to compare imagery-related effects between salient targets and non-salient targets (search asymmetry). In Study 3, I conducted a single experiment with the goal to dissociate imagery-related effects on early perceptual processing (N2pc) from those on late post-selection (marked by the SPCN component). In Study 4, I analyzed all previous data with a different approach to address how variations in imagery skills (subjective vividness ratings) modulated imagery-related effects. The general results revealed stronger and faster N2pc components, and faster reaction time, when searching for a target that matched a previously imagined object, compared to searching for a mismatched target. Neural signals during search were distinguishable and reaction time differed based on vividness ratings. The collective findings suggest that mental imagery is a potent strategy for completing search tasks and that the effects of imagery are bounded by individual imagery skills.