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Yoram Bonneh, Dov Sagi, Alexander Cooperman, Tobias Donner, David Heeger, Moshe Fried, Amos Arieli; Motion-induced blindness and microsaccades: Cause or effect?. Journal of Vision 2009;9(8):289. doi: 10.1167/9.8.289.
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© ARVO (1962-2015); The Authors (2016-present)
Subjective visual disappearance was suggested to be caused by reduced micro-saccade (MS) rate enabling image stabilization, enhanced adaptation and perceptual fading. We compared the dynamics of MS in Motion-Induced Blindness (MIB) and in physical disappearance. Observers reported the disappearance and reappearance of a single peripheral (2 deg, upper-left) high contrast Gabor patch on a gray background embedded in a rotating grid mask presented for 4 min periods. In a following experiment observers repeated the same task while presented with a stimulus sequence in which the Gabor patch was physically erased and redisplayed according to their MIB reports (Replay). To minimize MIB effects in the replay condition, the mask was slowed down (0.2 deg/sec). Eye movements and pupil size were recorded using a video based eye-tracker. We found a similar pattern and overall level of MS rate in the MIB and Replay conditions. Notably, the MS rates during sustained invisible periods, whether only perceptual or physical, were significantly lower (60%) than the MS rates in the corresponding visible periods. In both MIB and Replay, transitions were accompanied by transient changes in MS rates: decrease and increase with a disappearance and reappearance report respectively. Pupil size dynamics showed a similar trend with a smaller pupil corresponding to a lower MS rate. Additional experiments showed that eye movements induced by tracking a continuously jumping fixation reduce but do not eliminate disappearance. The results suggest that MS do not have a major causal role in MIB since they showed similar dynamics with (Replay) and without (MIB) physical disappearance, and since MIB can survive task-induced eye-movements. The opposite MS dynamics for appearance and disappearance, whether physical or only perceptual, together with a similar trend of pupil size dynamics, suggest that the eye-control mechanisms are informed about visibility.
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