Compression of distance judgments when viewing virtual environments using a head mounted display

Viewpoint oscillation improves the perception of distance travelled in static observers but not during treadmill walking

Optic flow has been found to be a significant cue for static observers’ perception of distance travelled. In previous research conducted in a large-scale immersive display (CAVE), adding viewpoint oscillations to a radial optic flow simulating forward self-motion was found to modulate this perception. In the present two experiments, we investigated (1) whether the improved distance travelled perceptions observed with an oscillating viewpoint in a CAVE were also obtained when the subjects were wearing a head mounted display (HMD, an Oculus Rift) and (2) whether the absence of viewpoint oscillations during treadmill walking was liable to affect the subjects’ perception of self-motion. In Experiment 1, static observers performed a distance travelled estimation task while facing either a purely linear visual simulation of self-motion (in depth) or the same flow in addition to viewpoint oscillations based on the subjects’ own head oscillations previously recorded during treadmill walking. Results show that the benefits of viewpoint oscillations observed in a CAVE persisted when the participants were wearing an HMD. In Experiment 2, participants had to carry out the same task while walking on a treadmill under two different visual conditions simulating self-motion in depth: the one with and the other without the visual consequences of their head translations. Results showed that viewpoint oscillations did not improve the accuracy of subjects’ distance travelled estimations. A comparison between the two experiments showed that adding internal dynamic information about actual self-motion to visual information did not allow participants better estimates.

Handles lost in non-reachable space

Recent evidence indicates that we experience manipulable objects as graspable, provided that they fall within our reaching space. Nevertheless, such evidence comes from studies using virtual objects that have poor ecological validity. Here, we used a spatial alignment effect paradigm and systematically examined this effect when a real handled object was presented at four different distances, namely near-reaching space, actual-reaching space, perceived-reaching space, and non-reaching space. Participants responded with either the right or the left hand as soon as the real object, a mug with the handle oriented toward the left or right, was presented. We found spatial compatibility effect only when the object was presented in the near-reaching and actual-reaching spaces. Results suggest that the activation of the potential actions to perform with objects is modulated by object accessibility. They also suggest that accessibility is exclusively linked to the actual rather than the estimated reaching ability of the perceiver. Results are discussed within the theoretical framework of embodied cognition.