Abstract
Change-blindness studies have much been conducted of how changes in target objects are detected or missed, but not so much focused on perceptual processing for non-target objects. A change detection task includes a target-present trial in which a change occurs between two scenes from one view to the next and a target-absent trial in which no change occurs between two consecutive scenes. In this study, we explored what differences might be observed between the target-present and target-absent trials when attention is diverted from a search array by attentional capture. Ten participants detected a change in the search array consisted of a fixation cross with 6, 12, 18 or 24 small bars. In the target-present trials one of the bars changed from red to green or vice versa. In the target-absent trials the same search display was presented once again. The participants' attention was diverted from the search array under the condition of attentional capture, resulting in the reduction of their attention to be directed to the search array. The results show that the target-present trials were more difficult than the target absent trials. Further, the effect of attentional capture was not observed in the target-present trials [F(1, 27) = 1.849, ns], whereas in the target-absent trials the effect was observed [F(1, 27) = 11.832, p < .01]. The lowered percentage correct by attentional capture in the target-absent trial means that the participants perceived “a change” despite the absence of a change object in the search array. This may indicates the possibility that participants detected a coarse change that the two scenes are different before they identified what feature or which object changed where and how it changed. It is possible to assume a mechanism in which perceiving such a coarse change is followed by comparison/verification of detailed representations to confirm where and what change occurred.
This work was supported by KAKENHI (22906011).