Error-correcting Perceptual Mechanisms

Abstract

The metric of the visual field is generally accurate but subject to changes dependent on stimulation. It is suggested that these changes indicate how the metric develops initially, and that the features of the visual signal which control the metric are the distributions of contours and of contour-curvatures over the field. These distributions are genetically prescribed for the organism; they correspond well with the distribution of these features in patterns derived optically from the environment; hence visual shapes and physical shapes are maintained in correspondence. Further short discussions concern physiological hypotheses and the extension of the above to senses other than vision.

On the scaling of size judgements by orientational cues

“…Is size constancy unique in this respect, or is it a manifestation of a much deeper underlying process of stimulus scaling? Some time ago, Andrews (1964) argued that constancy-like processes were part of a more general scheme for sensory calibration.…”

Adaptation, the Coding Catastrophe and Disaster Management in Natural Vision

“…Another important proposal regarding the functional benefits of adaptation involves the idea that it acts as a "graphic equalizer" (e.g., Andrews, 1964;Ullman and Schechtman, 1982;Anstis et al, 1998;Kohn, 2007;Webster, 2011;Haak et al, 2014a). This classic idea derives from luminance adaptation in the retina, where it reflects a form of dynamic range adjustment that allows us to see optimally in very dark or bright environments.…”

“…The motion aftereffect is a manifestation of neural adaptation: viewing a waterfall selectively reduces the responsiveness of neurons tuned to downward motion, leading to imbalanced responses to static stimuli with relatively stronger responses of neurons tuned to upward motion (Barlow and Hill, 1963). Neural adaptation is thought to be crucial for sensory processing, for instance, to cope with internal noise and/or to increase coding efficiency (Andrews, 1964;Ullman and Schechtman, 1982;Barlow and Földiák, 1989;Wainwright, 1999;Clifford et al, 2000;Kohn, 2007;Webster, 2011, Webster, 2015Haak et al, 2014a). Yet under some conditions, these benefits come at the cost of aftereffects, such as the illusion of false movement, which is clearly not beneficial for survival.…”

Visual Processing of Object Velocity and Acceleration

“…1990;White et al,1991) Interestingly, in our measurements, size constancy fails as the increment threshold approaches the size of a foveal cone. We speculate that size constancy operates only on the information supplied by the "local signs", perhaps by re-scaling the distance between the co-ordinates of each individual contour with changes in depth (Andrews, 1964), or perhaps by maintaining a separate reference size for every disparity (Morgan, 1991). Certainly it would require less information (fewer "bits") to store a neural representation of the distance between the spatial co-ordinates than to store a complete template of the luminance distribution of the reference size for every tested disparity.…”

“…Why do random variations in disparity increase this reference uncertainty? If the subjects were attempting to apply a different angular reference to every depth plane --use multiple standards --as scaling models of size constancy imply (Andrews, 1964;Morgan, 1991), they might misjudge the depth plane of the target, or estimate the implicit reference by averaging trials from adjacent depth planes, thereby increasing the reference error.…”