Misperception of motion in depth originates from an incomplete transformation of retinal signals

Abstract

Depth perception requires the use of an internal model of the eye-head geometry to infer distance from binocular retinal images and extraretinal 3D eye-head information, particularly ocular vergence. Similarly, for motion in depth perception, gaze angle is required to correctly interpret the spatial direction of motion from retinal images; however, it is unknown whether the brain can make adequate use of extraretinal version and vergence information to correctly transform binocular retinal motion into 3D spatial coordinates. Here we tested this hypothesis by asking participants to reconstruct the spatial trajectory of an isolated disparity stimulus moving in depth either peri-foveally or peripherally while participants' gaze was oriented at different vergence and version angles. We found large systematic errors in the perceived motion trajectory that reflected an intermediate reference frame between a purely retinal interpretation of binocular retinal motion (not accounting for veridical vergence and version) and the spatially correct motion. We quantify these errors with a 3D reference frame model accounting for target, eye, and head position upon motion percept encoding. This model could capture the behavior well, revealing that participants tended to underestimate their version by up to 17%, overestimate their vergence by up to 22%, and underestimate the overall change in retinal disparity by up to 64%, and that the use of extraretinal information depended on retinal eccentricity. Since such large perceptual errors are not observed in everyday viewing, we suggest that both monocular retinal cues and binocular extraretinal signals are required for accurate real-world motion in depth perception.

Motion-in-depth effects on interceptive timing errors in an immersive enviornment

“…Accurate perception of MID (both speed and direction) accurately is a complex process that requires integrating extra-retinal (e.g. gaze direction) and retinal information so that 2D information from the retinae are properly mapping to a 3D layout but this transformation can be incomplete (Murdison et al, 2019). It is clear that the differences in temporal errors as a function of speed depended on the angle of approach, as shown in Figure 6.…”

“…Moreover, speed discrimination thresholds are usually higher for MID than for lateral motion (Aguado & López-Moliner, 2019;Rushton & Duke, 2009)). It has also been shown that differences in perceived speed depend on which part of the retina is stimulated (Brooks & Mather, 2000;Murdison, Leclercq, Lefèvre, & Blohm, 2019) and well known biases in the perceived spatial trajectories (Aguado & López-Moliner, 2019;Harris & Dean, 2003;Lages, 2006;Murdison et al, 2019;Rokers, Fulvio, Pillow, & Cooper, 2018;Welchman, Tuck, & Harris, 2004) or in motion extent in depth (Lages, 2006). The variability in the perception of MID, including speed and direction, makes it worth studying the performance of response timing when dealing with objects moving in depth.…”

Motion-in-depth effects on interceptive timing errors in an immersive environment

“…Accurate perception of MID (both speed and direction) is a complex process that requires integrating extra-retinal (e.g., gaze direction) and retinal information so that 2D information from the retinae are properly mapped to a 3D layout, but this transformation can be incomplete 16 . It is clear that the differences in temporal errors as a function of speed depended on the angle of approach, as shown in Fig.…”

“…Compared to lateral motion, speed discrimination thresholds for MID are usually higher 13 , 14 , and prone to individual differences 15 . This is probably because there is an overabundance of available depth cues 16 that makes predictions on timing performance more difficult. When MID is involved, typical monocular cues include optical expansion 17 , shading and texture gradients 18 , 19 , kinetic depth cues and motion parallax, among others.…”

“…However, all these monocular and binocular retinal cues need the support of extra-retinal signals 23 for the estimation of 3D motion, that is MID. In addition to this diversity of cues, the perceived speed of MID depends on which part of the retina is stimulated 16 , 24 and the perceived spatial 3D trajectories or motion extent are affected by well known biases 14 , 16 , 25 – 28 . The variability in the perception of MID, including speed and direction, makes it worth studying the performance of response timing when dealing with objects moving in depth.…”