Is there a neural common factor for visual illusions?

Abstract

It is tempting to map interindividual variability in human perception to variability in brain structure or neural activity. Indeed, it has been shown that susceptibility to size illusions correlates with the size of primary visual cortex V1. Yet contrary to common belief, illusions correlate only weakly at the perceptual level, raising the question of how they can correlate with a localized neural measure. In addition, mounting evidence suggests that there is substantial interindividual variability not only in neural function and anatomy but also in the mapping between the two, which further challenges the findings of a neural common factor for illusions. To better understand these questions, here, we re-evaluated previous studies by correlating illusion strengths in a battery of 13 illusions with the size of visual areas and population receptive field sizes. We did not find significant correlations either at the perceptual level or between illusion susceptibility and visual functional neuroanatomy.

Testing claims nobody made – a response of Jastrzębowska et al.

“…Jastrzębowska, Ozkirli, Cretenoud, Draganski, and Herzog (henceforth, "JOCDH") recently published a preprint article (Jastrzębowska et al, 2023) in which they sought to conceptually replicate results from three of our studies (Moutsiana et al, 2016;Schwarzkopf et al, 2011;. All these studies investigated inter-and intra-individual differences in size perception measured psychophysically and estimates of the cortical magnification and spatial selectivity of primary visual cortex (V1).…”

Individual differences distinguish mechanisms underlying contextual size illusions

“…Given this diversity, it seems inconceivable there could be a common factor to all spatial contextual illusions, although this has not stopped researchers from searching for such factors (Axelrod et al, 2017; Cretenoud et al, 2021; Grzeczkowski et al, 2017; Jastrzębowska et al, 2023). A large psychophysical study on simultaneous contrast tasks found that the magnitudes of these illusions are mostly uncorrelated between stimulus dimensions (Bosten & Mollon, 2010), something in line with our own findings comparing size and luminance perception (Song, Schwarzkopf, & Rees, 2013).…”

“…Numerous paradigms exist for quantifying the magnitude of an observer’s perceptual illusions, each of which involves cognitive confounds to some degree: this includes adjustment/reproduction tasks (e.g. (Ho & Schwarzkopf, 2022; Jastrzębowska et al, 2023)), forced-choice procedures (e.g. (Schwarzkopf & Rees, 2013)), confidence ratings (Gallagher et al, 2019), and drift diffusion models (Sánchez-Fuenzalida et al, 2023).…”

“…Importantly, most of the studies failing to find correlations between most contextual illusions used adjustment procedures (Cretenoud et al, 2021; Cretenoud, Francis, et al, 2020; Cretenoud, Grzeczkowski, et al, 2020; Grzeczkowski et al, 2017; Jastrzębowska et al, 2023). Some of these experiments were conducted online or outside lab environments, allowing minimal control over stimulus characteristics and eye gaze.…”

You say predictor, we say common factor - a response to Schwarzkopf

“…We recently investigated the relationship between the surface area and population receptive field (pRF) sizes of human early visual cortices and susceptibility to a series of spatial illusions (Jastrzębowska et al, 2023). This was an attempt at direct and conceptual replication of a series of studies by Schwarzkopf and colleagues (Moutsiana et al, 2016;Schwarzkopf et al, 2011;Song et al, 2013).…”