Perceptual Constancy

Abstract

Our eyes deceive us when we look down railway tracks, but our brains do not. The rails appear to converge in the distance, but we know that the rails are parallel. We know that they are the same distance apart a mile down the track as they are where we are standing, so the brain says, "The tracks only appear to converge because they are distant." But how does the brian know that the tracks are distant? The brain answers, "They must be distant because they appear to converge." (The flow of this logic must shock computer programmers, but they are accustomed to the limitations of inferior hardware.) (Hunter et al., 2007, 82)

A simple optical flow model explains why certain object viewpoints are special

“…In Experiment 2, the selection of the “front” viewpoint compared to all other viewpoints arguably requires a 3D representation of the object as a whole, yet even in this case responses corresponded to geometric regularities predicted by the 2D model. As a result, the model also provides a route into understanding the origin of putative effects of the ‘perspectival’ appearance of objects (Morales et al, 2020; Storrs & Arnold, 2013; Thouless, 1931)— such as the perceived ‘elliptical nature’ of a coin seen slanted in depth—in the context of theories of vision that assume perceptual constancies (Burge, 2010; Cohen, 2014; Green, 2023; Walsh & Kulikowski, 1998). Specifically, we suggest that even when 3D object structure is estimated perfectly, comparisons between objects are made in terms of the estimated or predicted changes in the proximal stimulus involved in transforming one view to another.…”

Hill on perceptual relativity and perceptual error

“…A coin appears one way when viewed head‐on, another way when viewed at a slant. A white coffee mug appears one way when brightly illuminated, another way when in the shade (Cohen, 2015; Green & Schellenberg, 2018; Hill, 2020; Morales et al, 2020). Hill bolsters this familiar introspective case for perceptual relativity with abundant evidence from perceptual psychology.…”