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Nika Adamian, Patrick Cavanagh; Localization of flash grab targets is improved with sustained spatial attention . Journal of Vision 2016;16(12):1266. doi: 10.1167/16.12.1266.
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We examined the effect of spatial and temporal predictability on the flash grab illusion (Cavanagh & Anstis, 2013) where a target is briefly flashed on top of a moving texture as it reverses direction and its position is seen displaced in the direction of motion following the reversal. On each trial, subjects were shown a large rotating textured disc. At some point during the trial the motion reversed direction and at the same time a small probe was flashed on top of the texture and subjects reported its location. In the first experiment we varied spatial and temporal certainty together. The probe was presented at the same location on multiple consecutive reversals. We found that upon the first presentation at an unexpected location and time, the probe was perceived significantly more shifted compared to the subsequent repeat presentations. In the second study we compared the effects of spatial and temporal predictability on the strength of the flash grab illusion. Trials were presented in blocks and before each spatial block a cue indicated a range of possible target locations, whereas before each temporal block, a range of possible timings of the reversal was given. We found that the flash grab effect was reduced if the spatial distribution of targets within a block was limited to a range of 90° or less. By contrast, increasing the temporal predictability of the target did not reduce the flash grab effect. We assume that with an uncertain location, attention would be delayed in arriving at the test, increasing the motion-induced position illusion (Müsseler & Ascherschleben, 1998). However, temporal uncertainty does not appear to affect this attentional delay.
Meeting abstract presented at VSS 2016
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