Virtual Objects Look Farther on the Sides : The Anisotropy of Distance Perception in Virtual Reality

Etienne Peillard, Thomas Thebaud, Jean-Marie Normand, Ferran Argelaguet, Guillaume Moreau, Anatole Lécuyer

March, 2019

Abstract

The topic of distance perception has been widely investigated in Virtual Reality (VR). However, the vast majority of previous workmainly focused on distance perception of objects placed in frontof the observer. Then, what happens when the observer looks onthe side? In this paper, we study differences in distance estimationwhen comparing objects placed in front of the observer with objectsplaced on his side. Through a series of four experiments (n=85),we assessed participants’ distance estimation and ruled out poten-tial biases. In particular, we considered the placement of visualstimuli in the field of view, users’ exploration behavior as well asthe presence of depth cues. For all experiments a two-alternativeforced choice (2AFC) standardized psychophysical protocol wasemployed, in which the main task was to determine the stimuli thatseemed to be the farthest one. In summary, our results showed thatthe orientation of virtual stimuli with respect to the user introducesa distance perception bias: objects placed on the sides are system-atically perceived farther away than objects in front. In addition,we could observe that this bias increases along with the angle, andappears to be independent of both the position of the object in thefield of view as well as the quality of the virtual scene. This worksheds a new light on one of the specificities of VR environmentsregarding the wider subject of visual space theory. Our study pavesthe way for future experiments evaluating the anisotropy of distanceperception in real and virtual environments.

Type

Conference paper

Publication

IEEE Virtual Reality Conference

Why this matters

Distance perception in Virtual Reality is usually studied with objects placed directly in front of the observer. XR interfaces, however, routinely place notifications, tools, and collaborators throughout the visual field. This study asks whether perceived distance is the same in every viewing direction.

Study at a glance

Four experiments involving 85 participants used a two-alternative forced-choice psychophysical protocol. Participants compared the apparent distance of virtual objects in frontal and lateral directions while the studies controlled for field-of-view placement, exploration behaviour, available depth cues, and the richness of the virtual scene.

Key findings

Virtual objects located to the side were systematically perceived as farther away than frontal objects.
The difference increased with the angular separation from the observer’s forward direction.
The effect persisted when controlling for the objects’ placement in the field of view and for scene quality.

The results demonstrate an anisotropy of distance perception in VR: perceived space is not uniform around the observer. This provides a basis for studying how XR interfaces should place spatial content when reliable distance judgments matter.

In the doctoral research

This publication opens the doctoral research on perceptual biases in Mixed Reality. It establishes an observer-centred bias before the later studies examine object relations, scene cues, and display optics in Augmented Reality.