The degree of parallel/serial processing affects stimulus-driven and memory-driven attentional capture: Evidence for the attentional window account.

The issue of whether a salient stimulus in the visual field captures attention in a stimulus-driven manner has been debated for several decades. The attentional window account proposed to resolve this issue by claiming that a salient stimulus captures attention and interferes with target processing only when an attentional window is set wide enough to encompass both the target and the salient distractor. By contrast, when a small attentional window is serially shifted among individual stimuli to find a target, no capture is found. Research findings both support and challenge this attentional window account. However, in these studies, the attentional window size was improperly estimated, necessitating a re-evaluation of the account. Here, using a recently developed visual search paradigm, we investigated whether visual stimuli were processed in a parallel or a serial manner. We found significant attentional capture when multiple stimuli were processed in parallel within a large attentional window. By contrast, when a small window had to be serially shifted, no capture was found. We conclude that the attentional window account can be a useful framework to resolve the widespread debate regarding stimulus-driven attentional capture.