Abstract
Exogenous attention is characterized as having a rapid, short lasting, reflexive, involuntary activation, while endogenous attention has a slower onset and longer duration and is engaged voluntarily in a goal directed manner. There is controversy regarding exogenous attention as to whether or not perceptual enhancement (not reaction time) occurs in non-predictive cueing paradigms for accuracy judgments. The present experiment examines two types of attention based perceptual enhancement in a highly demanding divided attention task: location detection, and feature identification. The stimulus locations include one central fixation and six 7.5 degree eccentric locations evenly spaced around the central fixation location. After a non-informative pre-cue is presented at one location, the target, a number, is briefly displayed at some location while distractor letters are displayed at the other six locations. Targets and distractors in the periphery are 100% contrast, black, capital letters (with one being the target number), spanning one degree. The letters and numbers are followed by a new letter mask. Cue to mask onset time is varied from 80 to 520ms, which consists of varied stimulus onset asynchronies (cue to target duration), plus the target stimulus duration and the interstimulus interval between the target offset and mask onset. Exogenous attention is examined for trials with less than the length of time required to voluntarily shift attention via an eye movement (~200ms). Intervals longer than this are believed to utilize endogenous attention. Across all eight subjects, and for the less than 200ms pre-cue to mask intervals, an exogenous capture of attention via a non-predictive peripheral cue improves accuracy for identifying both where the target was presented (location) and what the target stimulus identity was (actual number), even with response bias (from location uncertainty) removed. The same results were observed for longer pre-cue to mask intervals that presumably include endogenous attention effects.
Meeting abstract presented at VSS 2012