1997 年 15 巻 2 号 p. 77-87
Previous research (Kawahara, 1996) suggest that visual attention is directed to the most salient stimulus in the visual field irrespective of the subjects' knowledge or intention (attentional capture). In the present study, we conducted two visual search experiments and confirmed the idea that visual attention is directed in the stimulus-driven way. Subjects searched for a target which was defined by motion. In one condition, the target was presented among static nontargets; in another condition, one of the nontarget was replaced with a task-irrelevant distractor which had a unique color. Experiment 1 showed that the presence of the distractor prolonged the reaction time for target identification even when the target can be detected independent of the total number of items in the stimulus display (display size). Decreasing the saliency of the distractor color diminished attentional capture (Experiment 2). These results are consistent with the notion of stimulus-driven way of attentional deployment. A further analysis and experiment were conducted to characterize the nature of attentional capture. The distance and the compatibility of features between the target and distractor were not significant determinant of attentional capture in the present study. Finally, a possibility and problem for proposing the single activation map model of attentional deployment was discussed.