Abstract
SummaryNeurons in the visual cortex quickly adapt to constant input, which should lead to perceptual fading within few tens of milliseconds. However, perceptual fading is rarely observed in everyday perception, possibly because eye movements refresh retinal input. Recently, it has been suggested that amplitudes of large saccadic eye movements are scaled to maximally decorrelate presaccadic and postsaccadic inputs and thus to annul perceptual fading. However, this argument builds on the assumption that adaptation within naturally brief fixation durations is strong enough to survive any visually disruptive saccade and affect perception. We tested this assumption by measuring the effect of luminance adaptation on postsaccadic contrast perception. We found that postsaccadic contrast perception was affected by presaccadic luminance adaptation during brief periods of fixation. This adaptation effect emerges within 100 milliseconds and persists over seconds. These results indicate that adaptation during natural fixation periods can affect perception even after visually disruptive saccades.
Highlights
Humans frequently accelerate their eyes to extremely high velocities (Bahill et al, 1975; Baloh et al, 1975) even though such saccadic eye movements disrupt and distort visual processing
It has been suggested that amplitudes of large saccadic eye movements are scaled to maximally decorrelate presaccadic and postsaccadic inputs and to annul perceptual fading
We found that postsaccadic contrast perception was affected by presaccadic luminance adaptation during brief periods of fixation
Summary
Humans frequently accelerate their eyes to extremely high velocities (Bahill et al, 1975; Baloh et al, 1975) even though such saccadic eye movements disrupt and distort visual processing (for a review see Binda and Morrone, 2018). For some animals, which lack a fovea (receptor density is uniform across the retina), making saccades would have no effect considering that the resolution of the visual information would stay the same. The fact that those animals make saccades leads to a second potential reason for why humans and other animals frequently interrupt fixations: avoiding perceptual fading due to unchanging retinal input over time, i.e., neuronal adaptation (Samonds et al, 2018). Perceived contrast of an unchanging visual input will decrease with the reduced spiking activity in the neuronal population (Movshon and Lennie, 1979) and eventually, it will be erased from vision (perceptual fading, Troxler, 1804). The authors proposed that preferred saccade amplitudes are based on the spatial properties of the visual scene (spatial frequency content) and the sizes of the areas from which neurons process information (receptive filed sizes)
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