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Fred H. Hamker, Arnold Ziesche, Heiner Deubel; Dynamic recurrent processing for coordinate transformation explains saccadic suppression of image displacement. Journal of Vision 2010;10(7):522. doi: https://doi.org/10.1167/10.7.522.
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© ARVO (1962-2015); The Authors (2016-present)
When we shift our gaze, the image on the retina abruptly changes. What are the mechanisms that establish our subjective experience of visual stability? This question has been more formally addressed by experiments in which the image is displaced during the saccade, showing that subjects do not notice small image displacements. The observation has been interpreted by a built-in assumption of visual stability according to which we align our pre-saccadic view with a reference found in the post-saccadic view (Deubel, Schneider, & Bridgeman, Vis Res, 1998), or similarly by a prior expectation that object jumps do not occur (Niemeier et al., Nature, 2003). We simulated the saccadic suppression of image displacement task as done by Deubel et al (Vis Res, 1996) with a dynamic recurrent basis function network of coordinate transformation which maps eye-centered into head-centered representations using realistic visual processing including visual latency, persistence and saccadic suppression. Eye position is not modeled as a continuous but rather discrete signal, which transiently switches from the pre- to the post-saccadic eye position. This model explains the suppression of displacement by simple dynamic properties of the visual system rather by higher-level strategies as emphasized in earlier theories: According to the simulations, the displacement is not perceived since the displaced stimulus interacts with the pre-saccadic stimulus trace. The head-centered representation of pre-saccadic stimulus feeds back to the incoming displaced stimulus response and stabilizes the representation in the presence of small displacements. The model can also explain the paradoxical target blanking effect in which displacements become apparent when the target is blanked before or after the saccade: in this case, no stabilization occurs because the pre-saccadic stimulus trace is missing.
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