Can Contrast-Response Functions Indicate Visual Processing Levels?

Abstract

Many visual effects are believed to be processed at several functional and anatomical levels of cortical processing. Determining if and how the levels contribute differentially to these effects is a leading problem in visual perception and visual neuroscience. We review and analyze a combination of extant psychophysical findings in the context of neurophysiological and brain-imaging results. Specifically using findings relating to visual illusions, crowding, and masking as exemplary cases, we develop a theoretical rationale for showing how relative levels of cortical processing contributing to these effects can already be deduced from the psychophysically determined functions relating respectively the illusory, crowding and masking strengths to the contrast of the illusion inducers, of the flankers producing the crowding, and of the mask. The wider implications of this rationale show how it can help to settle or clarify theoretical and interpretive inconsistencies and how it can further psychophysical, brain-recording and brain-imaging research geared to explore the relative functional and cortical levels at which conscious and unconscious processing of visual information occur. Our approach also allows us to make some specific predictions for future studies, whose results will provide empirical tests of its validity.

Columnar organization of mid-spectral and end-spectral hue preferences in human visual cortex

“…Unexpectedly, we also found a weaker but reversed hue bias for mid-spectral (relative to end-spectral) hues in V2 and V3, at the area level. At least part of this difference could be due to the steeper contrast response function of V2/V3 compared to V1 (Hall et al, 2005; Breitmeyer et al, 2018). Specifically, as indicated in Table S2, our end-spectral hues contained a higher ‘total color contrast’ compared to mid-spectral hues.…”

Contrast sensitivity indicates processing level of visual illusions.

“…Another important factor to consider is the obvious fact, noted by Breitmeyer, Tripathy, and Brown (2018), that whenever a perceptual judgment is made, it requires that both the target stimulus and the stimulus used to assess the illusory effect be visible. That is to say, even if low (precortical and) cortical levels of processing dominate in producing an illusory effect (as in simultaneous-brightness induction), one would expect involvement of high-level cortical percept-dependent processes to be also involved in the very act of making a perceptual judgment.…”

“…Because there are many other visual illusions (e.g., Müller-Lyer, Zöllner, Delboeuf, Hermann grid, Ebbinghaus, Hering) and visual phenomena (e.g., apparent motion, masking, crowding), in future work psychophysical and neural CRFs can also assist in gaining a better understanding of which areas and levels in the visual cortical hierarchy are involved and the extent to which they are involved in generating these visual illusions and phenomena (see Breitmeyer et al, 2018).…”

Visual Characteristics of Adults with Long-Standing History of Dietary Exposure to Mercury in Grassy Narrows First Nation, Canada

“…Methyl Hg-related decrease in CS was first observed with visual evoked potential testing in patients suffering from Minamata disease in Japan [ 27 ]. Some authors suggested alteration of CS function could be connected to methyl Hg accumulation in the retina [ 39 , 71 , 72 ], or as a result of alterations in the visual cortex, where processing of contrast occurs [ 19 , 84 , 85 , 86 ]. Developmental exposure and adulthood exposure to methyl Hg may produce different the patterns of spatial and temporal vision defects [ 42 ].…”