Abstract
The cost of attending to a visual event can be the failure to detect other events. Are these costs the same regardless of whether attention is summoned in a top-down (goal-driven) or bottom-up (stimulus-driven) fashion? The attentional blink paradigm demonstrates that searching for and attending to a target presented in an rapid serial visual presentation (RSVP) of distractors can dramatically impair one's ability to detect a second, probe target (Raymond et al., 1992). In the present experiments, we asked whether the presentation of novel, task-irrelevant and unexpected stimuli could also lead to failures in probe detection.
Subjects searched for a single target in an RSVP of distractors, with the rare (%12) presentation of ‘oddball’ stimuli occurring at different lags prior to the presentation of the probe target. For half of the 24 subjects, the targets and distractors were letters and the oddballs were faces, while for the other half the target/distractor and oddball sets were reversed. For both groups, subjects were profoundly impaired at detecting the probe when it occurred 370 ms, but not 730 ms, after oddball presentations. Strikingly, this perceptual deficit was extremely short-lived, as the impairment vanished by the 4th oddball presentation. Control experiments rule out that this perceptual deficit is a result of masking, startle-induced eye blinks or memory impairment. A final experiment in which the oddballs consisted of a heterogeneous set of visual stimuli showed again a rapid, but this time incomplete, habituation pattern with moderate levels of deficit leveling off by the 4th oddball and persisting across the 6 oddball presentations.
These results suggest that the presentation of novel, unexpected stimuli lead to a profound but extremely short-lived perceptual deficit. The lifespan of this impairment leads us to speculate that it represents a novel and distinct form of attentional deficit to explicit perception.