Sex Differences in Temporal but Not Spatial Attentional Capture.

The accuracy of detecting or identifying a target decreases when a salient distractor is presented. This decrease is explained by the temporal or spatial diversion of attention to the distractor and thus is referred to as attentional capture. Using temporal and spatial visual search tasks, we examined whether there are sex differences in attentional capture. In Experiment 1A, a temporal visual search task measured attentional capture in the temporal domain by asking participants (97 men and 92 women) to identify a target embedded in a rapid stream of nontarget letters while ignoring a preceding peripheral distractor. In Experiment 2, a spatial visual search task measured attentional capture in the spatial domain by asking participants (146 men and 83 women) to detect a target among spatially distributed nontarget items while ignoring a distractor presented simultaneously. Our results indicate that attentional capture occurred in both tasks. In Experiment 1A, the magnitude of capture was significantly larger for women than men. In Experiment 1B, we confirmed sex differences in temporal attentional capture by recruiting a new set of participants (141 men and 85 women). In Experiment 2, the magnitude of capture was comparable between the sexes. These results suggest that women are more sensitive to bottom-up signals than men when they engage in a temporal search task and could be explained in terms of sex differences in the ability of adjusting the size of attentional window, within which attention is allocated to the most salient item.

Attentional capture during attentional awakening.

We investigated whether attentional set is available at the beginning of a trial or whether it develops gradually within a trial. Thus, we manipulated the time from the onset of a trial to a target and observers' search strategy. We also observed the effect of the presence or absence of distractors as an index of the temporal development of attentional set. Participants identified a target letter embedded in a stream of rapidly presented nontargets while ignoring peripheral distractors. Baseline accuracy when no peripheral distractor was presented increased as the target appeared later in the stream, suggesting attentional awakening. Identification accuracy was impaired by the presence of peripheral distractors (i.e., attentional capture) early in the stream only when observers adopted the feature search mode. The magnitude of attentional capture increased over the course of the first 1,000 ms of a trial under the singleton detection and feature search modes. These results suggest that singleton detection mode requires time for a bottom-up signal to be effective in capturing attention, whereas the feature search mode does not require such a warm-up period to be effective and is available from the beginning of viewing the stream.

Attentional capture decreases when distractors remain visible during rapid serial visual presentations.

The identification of a central visual target is impaired by the onset of a peripheral distractor. This impairment is said to occur because attentional focus is diverted to the peripheral distractor. We examined whether distractor offset would enhance or reduce attentional capture by manipulating the duration of the distractor. Observers identified a color singleton among a rapid stream of homogeneous nontargets. Peripheral distractors disappeared 43 or 172 msec after onset (the short- and long-duration conditions, respectively). Identification accuracy was greater in the long-duration condition than in the short-duration condition. The same pattern of results was obtained when participants identified a target of a designated color among heterogeneous nontargets when the color of the distractor was the same as that of the target. These findings suggest that attentional capture consists of stimulus onset and offset, both of which are susceptible to top-down attentional set.

Nonspatial interdimensional attentional capture.

Accuracy in identifying a target is impaired by a task-irrelevant singleton distractor even when the target and distractor appear in the same location. However, whether this impairment, known as a nonspatial interdimensional attentional capture, is contingent on a top-down attentional set or determined by stimulus-driven signals from distractors is unclear. To examine whether interdimensional attentional capture is affected by a top-down attentional set, the present study explicitly manipulated observers' search strategies (the singleton detection or feature search modes) and the number of objects consisting of the search items. The results indicated that interdimensional attentional capture occurred even under the feature search mode but that the capture effect decreased under this search mode irrespective of the number of distractors, suggesting that top-down knowledge was effective in modulating nonspatial interdimensional capture.