Sustained spatial attention excludes external noise

摘要

The mechanism of attention is a central topic in neurophysiology, functional imaging, and behavioral studies. However, neurophysiology experiments often study cellular responses when the animal attends to one location for a prolonged period of time (sustained attention[sup]1[/sup]), while human behavioral studies often use pre-cues to direct subjecta??s attention to different locations trial by trial (transient attention[sup]2[/sup]). Here, we conducted a human behavioral study based on a sustained attention paradigm more often used in a monkey experiment [sup]1 [/sup]. Four synchronized RSVP streams of Gabors were presented in each trial. Each stream consisted of 10 distractors, all oriented at 45?° clockwise, and one potential target, ?±11?° from 45?°, that occurred between the 3[sup]rd[/sup] and the 10[sup]th[/sup] temporal positions. The four potential targets, presented in the four locations simultaneously, had independently chosen orientations. Subjects were instructed to maintain fixation (monitored by an eye-tracker) and attend to one of the four locations throughout each block of trials. A central report cue, presented 150 ms after the target presentation and consistent with the block cue 62.5% of the time, directed the subjects to report the orientation of the target in the cued location. In the invalid condition, the report cue pointed to one of the other three locations with equal probability. Full psychometric functions were measured at 4-5 external noise levels. Block cuing improved performance only in high external noise conditions for three out of four subjects. The other subject showed no significant attention effect. The data were fit with the perceptual template model [sup]3[/sup]. Consistent with studies on transient attention [sup]2[/sup], we identified an external noise exclusion mechanism in sustained attention. (1.Cohen & Maunsell, 2009; 2. Dosher & Lu, 2000; 3. Lu & Dosher, 1998)