Ability to identify scene-relative object movement is not limited by, or yoked to, ability to perceive heading

Abstract

During locomotion humans can judge where they are heading relative to the scene and the movement of objects within the scene. Both judgments rely on identifying global components of optic flow. What is the relationship between the perception of heading, and the identification of object movement during self-movement? Do they rely on a shared mechanism? One way to address these questions is to compare performance on the two tasks. We designed stimuli that allowed direct comparison of the precision of heading and object movement judgments. Across a series of experiments, we found the precision was typically higher when judging scene-relative object movement than when judging heading. We also found that manipulations of the content of the visual scene can change the relative precision of the two judgments. These results demonstrate that the ability to judge scene-relative object movement during self-movement is not limited by, or yoked to, the ability to judge the direction of self-movement.

Detection of scene-relative object movement and optic flow parsing across the adult lifespan

“…First, flow parsing does not depend on prior recovery of heading (Warren et al, 2012). Second, the precision of flow parsing is not limited by the precision of heading recovery (Rushton, Chen, et al, 2018). Experiment 1 therefore reinforces the idea that heading and flow parsing, despite both relying on optic flow, involve different neural processing.…”

“…We chose to use close objects to minimize the conflict between accommodation and convergence associated with viewing a stereo display (see Wann, Rushton & Mon-Williams, 1995). So that angular velocities remained comparable to those experienced when walking, simulated self-movement speed was scaled down accordingly (see Rushton, Chen & Li, 2018, for further explanation). A white fixation cross was presented at the center of the volume and a white probe sphere (0.2°diameter) was randomly presented either −2.4°(left) or 2.4°(right) from the fixation cross at the same depth.…”

“…In Experiment 1 we used a paradigm we have developed previously for measuring ability to detect scene-relative object movement from visual information alone (Rushton, Chen, et al, 2018). In this paradigm, stationary participants view a field of three-dimensional objects moving on the screen (and the retina).…”

“…If complete subtraction of optic flow were possible then any remaining retinal motion would be due, unambiguously, to scene-relative movement of other objects in the environment. Evidence for the existence of an optic flow parsing mechanism that performs exactly this kind of global subtraction operation has now been presented by several groups, across many studies, using varied experimental techniques ( Rushton & Warren, 2005 ; Warren & Rushton, 2007 ; Rushton, Bradshaw, & Warren, 2007 ; Warren & Rushton, 2008 ; Warren & Rushton , 2009a ; Warren & Rushton,2009b ; Matsumiya & Ando, 2009 ; MacNeilage, Zhang, DeAngelis, & Angelaki, 2012 ; Warren, Rushton, & Foulkes, 2012 ; Rushton, Foulkes, & Warren, 2013 ; Foulkes, Rushton, & Warren, 2013b ; Fajen & Matthis, 2013 ; Layton & Fajen, 2016 ; Niehorster & Li, 2017 ; Rogers, Rushton, & Warren, 2017 ; Rushton, Niehorster, Warren, & Li, 2018 ; Rushton, Chen, & Li, 2018 ).…”

Heading perception from optic flow in the presence of biological motion

“…In fact, Riddell and Lappe (2017) found that observers use biological motion information to identify the separate walker motion and self-motion components in a scene. Rushton, Chen, and Li (2018) also found that the ability to identify object motion is not limited by, or yoked to, the ability to perceive heading during self-motion. These findings support the proposal that the identification of object motion and the perception of heading during self-motion involves separate visual pathways (Rushton, Niehorster, Warren, & Li, 2018).…”