Negative priming and covert attention: Implications for studying clinical populations with attentional deficits
We investigated the covert attention processes at play when selecting task-relevant information and filtering out task-irrelevant information using a modified Negative Priming (NP) paradigm. We disambiguated covert attention—which occurs in the absence of eye movements—from overt attention by presenting lateralized stimuli for brief durations. Subjects determined whether a target was symmetrical or asymmetrical, attending covertly to the lateralized target while fixating centrally. When the target was difficult to select (Overlapping-Distractor condition), negative priming occurred: Previous viewing of the target impaired performance. However, when the distractor was easy to select (Contralateral-Distractor condition), positive priming occurred: Previous viewing of the target facilitated performance. Results indicate that even under conditions of covert attention, the selection process included a construction of the representation of the novel target as well as of the novel task-irrelevant distractor.