Abstract
Previous visual search studies suggest that an attentional template for the target can be prioritized, but the breadth and nature of this attentional template has not been clarified. Grouping features into objects and objects into categories should facilitate search performance by maximizing the amount of information carried by the attentional template. A series of six N2pc ERP studies shows the emergence of the benefits and costs of grouping during visual search. Study 1 confirms that searching for 1 item (a letter) is more efficient than 2+ items (multiple letters) at both neural (attenuated N2pc) and behavioral levels (slower reaction time and lower accuracy). Regarding the benefits of grouping, Study 2 shows that if category knowledge can be applied during visual search, 1-item (a letter) and multiple-item search (any letter) is very similar. Study 3 extends this finding to real-world objects (clothing/faces). Using novel stimuli, Study 4 shows that a heterogeneous set of items grouped by an abstract rule and not by common perceptual features can facilitate search. Regarding the costs of grouping, when asked to search for one item in a category (search for the letter "A") and a foil item from the category appears (the letter "R"), participants exhibit attentional capture to the foil at both neural and behavioral levels (Study 2). Study 5 shows that the "foil effect" is predicted by prior experience (distinguishing healthy and unhealthy foods based on dieting intensity). Study 6 shows that the foil effect emerges over one experimental session via training with novel stimuli. Taken together, these six studies show how the emergence of categorically-based attentional templates can help overcome efficiency limitations in visual search by constraining the scope of target search due to previous knowledge, yet at the cost of false alarms to non-targets that fall within the search category.
Meeting abstract presented at VSS 2016