An illusory distortion of moving form driven by motion deblurring D H Arnold1, W Marinovic2 |
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1Perception Lab, University of Queensland, Australia |
| Many visual processes integrate information over time – temporal integration. One consequence is that retinal motion can generate blurred form signals, similar to motion blur captured in photography at slow shutter speeds. Subjectively, retinal motion blur tends to be invisible. One suggestion is this ensues because humans can’t distinguish focused from blurred moving form. We noticed a novel illusion that seems to challenge this view. The apparent shape of circular moving objects can seem distorted when their rear edges lag leading edges by ~60ms, with a portion of rear extremities suppressed from awareness. We also found that sensitivity for detecting blur, and for discriminating between blur intensities, is uniformly worse for physical blurs behind moving objects, as opposed to in-front. These ‘dipper’ functions are consistent with blur having to reach a threshold intensity for detection, and with this threshold being greater for signals trailing behind moving contours. This, and our novel illusory distortion of moving form, could ensue from the biphasic temporal impulse response function, with a suppressive phase ~60ms after stimulus onset. Accordingly, form signals behind moving contours would be subject to a time dependent suppression, bringing about deblurring and, in some circumstances, an illusory distortion of moving form. |
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