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.
Highlights
Extant psychophysical evidence indicates that cortical processing has a multi-level functional hierarchy [1,2]
The metacontrast level is followed by a higher level at which visual crowding occurs, which in turn is followed by the level at which object-substitution masking (OSM) occurs [2]
REVIEW brain-imaging studies indicate that the anatomical sites2 of with OSM are found at the post-striate, lateral occipital complex but not at the striate level [17], they parahippocampal place area (PPA) [14]; and metacontrast correlates are most likely found at cortical have produced mixed results as to what cortical levels contribute to crowding, and how they do sites beyond V2 [15,16]
Summary
Extant psychophysical evidence indicates that cortical processing has a multi-level functional hierarchy [1,2]. REVIEW brain-imaging studies indicate that the anatomical sites of with OSM are found at the post-striate, lateral occipital complex but not at the striate level [17], they parahippocampal place area (PPA) [14]; and metacontrast correlates are most likely found at cortical have produced mixed results as to what cortical levels contribute to crowding, and how they do sites beyond V2 [15,16]. To have assistproduced the search forresults levelsasoftoprocessing involved in the various visual mixed what cortical levels contribute to crowding, andphenomena how they do discussed so above and additional ones, we suggest on the basis of studies for which data are already available that [5,18,19]. Evidence supporting rationale for above and additional ones, we suggest on the basis of studies for which data are already available tying processing levels to contrast response functions is outlined below. The evidence supporting our rationale for tying processing levels Response to contrast response functions is outlined below
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