It seems obvious to lay people that neurotypical humans experience color equivalently across their entire visual field. To some neuroscientists, psychologists and philosophers though, this claim has been met with skepticism, as neurophysiological evidence indicates the mechanisms that support color perception degrade with eccentricity. However, the argument that this entails altered color experience in peripheral vision is not universally accepted. Here, we address whether color experience is essentially equivalent between central and peripheral vision. To assess this, we will obtain similarity relationships between color experiences across the visual field using both on-line and laboratory-based far-field displays, while removing the confounds of saccades, memory, and expectation about color experiences. Our experiment was designed to provide clear evidence that would favor either unchanged or altered color experience relationships in the periphery. Our results are consistent with lay people's phenomenological reports: Color experiences, as probed by similarity relationships in central vision and the far field (60°), are equivalent when elicited by large stimuli. These findings challenge the widespread view in philosophy and cognitive science that peripheral color experiences are illusory, and are discussed in the context of their related neurophysiological, psychophysical, and philosophical literature.
Whether or not depth perception influences brightness and/or lightness perception has been repeatedly discussed, and some studies have emphasized its importance. In addition, a small number of studies have empirically tested and shown the effect of depth inversion, such as seen in the Mach card illusion, on perceived lightness, and they interpreted such results in terms of lightness constancy. However, how perceived brightness changes contingent on depth inversion remains unexplained. Therefore, this study used the matching method to examine changes in brightness perception when depth inversion is observed. We created and used a three-dimensional (3D) concave object, composed of three sides made of card stock, which could be perceived as having two different shapes in 3D; it could be perceived as a horizontal concave object, corresponding to its actual physical structure, and as a convex standing object, similar in shape to a building. Participants observed this object as both a concave object and as a convex object, and judged the brightness of its surfaces during each observation. Our results show that the perception of the brightness of the object’s surfaces clearly changed depending on the perception of depth. When the object was seen as convex, one part of the surface was perceived as darker than when the object was seen as concave, but the other part of the surface remained unchanged. Here we discuss the relationship between depth perception and brightness perception in terms of perceptual organization.
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