Discrimination of a Right Angle with Monocular and Cyclopic Perception

Abstract

Psychophysical tests with monocular and cyclopic perception were carried out to evaluate the accuracy of discrimination of right, acute, and obtuse angles. Tests with monocular perception were carried out with stimuli made by light line segments, spots, or elements of the Oppel-Kundt and Muller-Lyer figures. In tests with cyclopic perception, pairs of V-shaped stimuli with an identical orientation in the visual field and equal length of the sides but different divergence angles were presented to the different eyes of subjects. The test data demonstrated features of the perception of a right angle, namely, a high accuracy of reproduction, periodicity of errors as a function of the general orientation of a stimulus, similar characteristics of the manifestation of geometric illusions in angle reproduction and length comparison, and the manifestation of Hering's law in cyclopic perception. These results agree with the multilocal hypothesis, which explains the perception of right and other angles on the basis of the information about the coordinates of stimulus parts.

A role of rectangularity in perceiving a 3D shape of an object

“…The sensitivity to a relative orientation between two line-segments in the frontoparallel plane is higher when the orientation is perpendicular (Koshmanova & Sawada, 2019;Dvoeglazova et al, 2021;Chen & Levi, 1996;Heeley & Buchanan-Smith, 1996;Nundy et al, 2000, see also Regan et al, 1996). On the other hand, the perception of the relative orientation between the line-segments is also biased toward being perpendicular (Carpenter & Blakemore, 1973;Bulatov et al, 2005;Nundy et al, 2000). Xu et al (2018) thought that this higher sensitivity and bias can be explained by the likelihood of having a retinal image projected from a perpendicular angle in a 3D scene (Xu et al, 2018;Nundy et al, 2000).…”