Leonid L. Kontsevich

The influential uncertainty model [J. Opt. Soc. Am. A 2, 1508 (1985)] attributes nonlinear contrast sensitivity near threshold to the inability of the observer to discriminate between the signal from stimulated locations and the noise from nonstimulated locations. We introduce an alternative interpretation, the distraction model, to describe the behavior of an observer who knows exactly which location was stimulated but may miss the test stimulus because attention has been distracted by irrelevant (noise) signals. For any stimulus sample, the observer is assumed to be certain of whether this sample is relevant or irrelevant to the stimulus. The nonlinear effects predicted by the distraction model without uncertainty are similar to those predicted by the uncertainty model.

This study presents three findings concerning the mechanisms of depth perception. First, the shape of the three-dimensional percept evoked by two-frame motion is defined solely by the rotation component around an axis in the frontoparallel plane; the visual system assigns a default value to this rotation component to arrive at a unique solution. Second, when the visual axes of two eyes are almost parallel, the visual system uses a default vergence value to reconstruct stereoscopic depth. Third, the default vergence and default rotation angles are highly correlated across subjects. This correlation implies that the two modalities share a common scaling default at an internal level.