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Abstract:
When a brief blank is presented between two static images, attention is required to detect differences between those images (Rensink, 2000 Visual Cognition 7 345 - 376).
A study is reported in which attention either remained at fixation (no precue), or was drawn to one of four positions away from fixation at random by cuing for 50 ms. At a variable duration after cue offset, the whole screen blanked for 50 ms in order to induce 'change blindness'. In the pre-flash image, red or green squares were placed on 50 of tested positions at random. In the post-flash image, a square was placed at one position that had previously been blank. Fixation was monitored. The proportion of answers above chance at a given point indicated the strength of attention there.
The results show that while the shape of the 'window of attention' is approximately round in the no-precue condition, it resembles an ellipse with high aspect ratio in the cue conditions. This 'ellipse' is roughly centred at fixation and has the cued position near one end. Surprisingly, change detection is also enhanced on the opposite side of the fixation point from the cued location. The window seems to stretch like a sheet of latex both toward and away from the cued location simultaneously, before regaining its original form.
