Abstract
Perception of the second of two rapidly sequential targets (T1, T2) is impaired if the temporal lag between them is short. This attentional blink (AB) is said to occur because T1 preoccupies attentional resources leading to a shortage of attention for, and subsequent failure in judgement of T2. We examined whether or not the attention preoccupied by T1 carries the common characteristic of spatial attention, that is, local facilitation of information processing. To index the facilitation, we utilized an attention sensitive phenomenon known as the shooting line illusion in which observers see a progressively drawn line from the attended end to the other. In a trial, three RSVP streams of digits (distractors) and an alphabet (target) were displayed forming an imaginary equiangular triangle. Two streams contained distractors and a target, while the other had distractors only. A probe line was presented with T2, between T2 and another item. The temporal lag between T1 and T2 ranged from 100 to 700 ms. Observers were to identify T1 and T2, and to indicate the perceived direction of the probe line. We hypothesized that if attention captured by T1 has a spatial nature and thus, facilitates local processing of information, then the probe line will be perceived as if it was drawn from the side of T1 to the other side. Contrary, if attention captured by T1 has unitary and non-spatial nature, then the shooting line illusion will not be perceived. A significant AB was obtained. During this AB period, the shooting line motion was perceived to emanate from the end where T1 was presented. The motion sensation of a shooting line was especially strong at shorter lags. This result suggests that the attention engaged by T1 involves local facilitation of the spatially adjacent location. This finding may enable us to distinguish between two stage and competition models of AB.
Support: JSPS and Satow's Research Fund for Behavioural Science.