Abstract
Neurons in the visual cortex quickly adapt to constant visual stimulation, which should lead to perceptual fading within tens of milliseconds. However, perceptual fading is rarely observed in natural vision, which may be due to eye movements refreshing retinal input. Recently it has been suggested that the amplitudes of large saccadic eye movements are scaled to maximally decorrelate the pre- and postsaccadic inputs and thus serve to annul perceptual fading (Samonds, Geisler, & Priebe, 2018). Here we investigated whether short-term adaptation within natural fixation durations can survive a saccade and influence perception at all. To investigate rapid adaptation effects on perception, we developed a paradigm in which participants executed a horizontal saccade along a gap between two vertically oriented luminance gratings each with a different spatial frequency chosen to either correlate or anticorrelate pre- and postsaccadic retinal inputs given the saccade amplitude. The correlated grating resulted in the same retinal input before and after the saccade; the anticorrelated grating resulted in an inverted contrast polarity postsaccadically. Participants indicated which grating had the higher contrast after the saccade. Measuring the point of subjective equality (PSE) over various postsaccadic contrast differences between the gratings, we found large and reliable PSE shifts indicating lower perceived contrast of the correlated grating. Varying presaccadic adaptation duration revealed an effect after a few 100 milliseconds of adaptation. Delaying the postsaccadic stimulus onset revealed that the effect survived even our longest delay of 1.6 seconds. Our results show that adaptation can be strong, rapid, and persistent enough to attenuate perceived contrast within natural fixation durations, and that this effect can outlast a large saccade despite the strong disruption of visual input during the saccade. Our findings support the assumption that optimal saccade amplitudes serve as means to decorrelate pre- and postsaccadic inputs and to counteract perceptual fading.