Size aftereffect is non-local

Abstract

It is well known that prolonged exposure to a certain size stimulus alters the perceived size of a subsequently presented stimulus at the same location.How the rest of the visual space is affected by this size adaptation, however, has not been systematically studied before. Here, to fill this gap in literature, we tested size adaptation at the adapter location as well as the rest of the visual space. We used peripherally presented solid discs (Experiment 1) and rings (Experiment 2) as adapter and target (test) stimuli. Observers adapted to a mid-sized stimulus and judged the size of the subsequently presented smaller or larger target stimuli. Results showed that the perceived sizes of target stimuli were repelled away from the adapter size, not only at the adapter location but also at distant locations. These findings demonstrate that size adaptation causes widespread distortion of the visual space and alters perceived size. We discuss possible computational models that may underpin the perceptual effect.

The spatial properties of adaptation-induced distance compression

“…Our findings are at odds with a recent study of the size aftereffect ( Altan & Boyaci, 2020 ), in which a very broad tuning was found (up to 8 degrees of visual angle from the adapted area, 10–20% compression, and ∼5% expansion of apparent size). However, in this study, eccentricity was confounded with distance between adapted and test locations.…”

“…The lateral occipital cortex and the superior parietal cortex have also been implicated in illusory size perception ( Kreutzer, Weidner, & Fink, 2015 ; Plewan, Weidner, Eickhoff, & Fink, 2015 ; Shen, Zhang, & Chen, 2016 ; Zeng, Fink, & Weidner, 2020 ), with feedback projections to the early visual areas having been proposed to mediate the changes seen in early visual cortex ( Chen et al, 2019 ; Koivisto, Railo, Revonsuo, Vanni, & Salminen-Vaparanta, 2011 ; Zeng et al, 2020 ). Furthermore, there is some evidence that size aftereffects can transfer across space ( Altan & Boyaci, 2020 ; Corbett & Melcher, 2013 ), suggesting that additional mechanisms beyond primary visual cortex contribute to size perception.…”

Size adaptation: Do you know it when you see it?

“…Typically, it is assumed that two objects of equal size should not influence each other (here, there should be no opportunity for a repulsive effect from a neutral adaptor on its target, given that the values are the same). Moreover, adaptation is typically viewed as a spatially isolated repulsive aftereffect, meaning that a stimulus of a given value should cause any differing subsequent stimulus to be perceived as farther from that value only when presented in the corresponding region (a fact that is actually not true for size adaptation; see Altan & Boyaci, 2020). What our results thereby suggest is that some factor other than size (at a given location) is influencing the observed adaptation effect.…”

Tilt aftereffect spreads across the visual field

“…For example V1 activity modulated by feedback from higher-level visual areas may have a causal relation with the spread of the effect. Therefore, future studies testing such models in conjunction with neuronal activity in V4 and other visual areas would be required for a better understanding of the origin of the spread of figural aftereffects including TAE and the size aftereffect (Altan & Boyaci, 2020).…”

“…In general, however, TAE and other perceptual aftereffects are commonly considered localized with few exceptions (see for example Altan and Boyaci (2020) for the spread of size adaptation aftereffect across the visual field). How the perceived tilt of a contour is affected by an adapter located at another location has not been investigated systematically before.…”