The cyclopean eye is relevant for predicting visual direction

Abstract

Wells-Hering's laws summarize how we process direction and predict that monocular stimuli appear displaced with respect to the viewer, but not with respect to other seen objects [Erkelens, C. J.,& van Ee, R. (2002). The role of the cyclopean eye in vision: sometimes inappropriate, always irrelevant. Vision Research 42, 1157-1163] criticized this view and claimed that there is no perceptual displacement of these stimuli. We challenge their claim and improve on shortcomings of past studies. LEDs were monocularly presented to the observers, without their knowledge of which eye was being stimulated. Viewing distance was 9-10 cm; fixation distance was 30 cm. Observers reported the perceived relative and absolute directions of monocular stimuli. Our results are consistent with Wells-Hering's laws.

Simulating the Cortical 3D Visuomotor Transformation of Reach Depth

“…Hand and target azimuth (p X ) and elevation (p Z ) angles were encoded in a set of topographically arranged units representing cyclopean retinal positions [73], [74], [75] relative to the fovea. These units had Gaussian receptive fields (width σ = 20deg) and their activations were specified by:where x i and z i are each unit's preferred directions.…”

Two historical strands in studying visual direction1

“…This high accuracy (correctness) of judgment of stimuli being aligned or not aligned is defined with respect to an eye, but usually observers know which eye is being used and they are likely to report that the stimuli are aligned or not aligned with respect to that eye. However, stimuli aligned with one eye appear to point to a reference point when information about which eye is stimulated is not available to the observer (Khokhotva et al., 2005); they appear to point to the bridge of the nose.…”

Computations for geometrically accurate visually guided reaching in 3-D space

“…Therefore, we first projected the actual hand position and the desired reaching target position onto the spherical retina, and we compared these in retinal coordinates to compute the gaze-centered Bmotor error command[ for the reach plan ( Figure 2). Based on current knowledge from psychophysical studies, we used a single 3-D (cyclopean; e.g., Khokhotva, Ono, & Mapp, 2005;Ono & Barbeito, 1982) retinal Bmotor error[ command. This 3-D retinal error was computed from a two-dimensional (2-D) angular difference between target and hand positions and includes a third component, that is, the radial distance between hand and target to specify depth.…”