Viewpoint oscillation improves the perception of distance travelled based on optic flow

Abstract

When static observers are presented with a visual simulation of forward self-motion, they generally misestimate distance travelled relative to a previously seen distant target: It has been suggested that this finding can be accounted for by a "leaky path integration" model. In the present study, using a similar experimental procedure, this result was confirmed. It was also established that combining the translational optical flow with simulated head oscillations (similar to those during natural walking) improved the subjects' perception of the distance travelled in comparison with a purely translational flow. This improvement may be attributable to the fact that an optic flow pattern resembling that associated with walking enhances the path integration process. In a subsequent experiment, we investigated whether it was the biological or the rhythmical characteristics of the simulation that enhanced the subjects' estimates of the distance travelled. The results obtained confirm that adding rhythmic components to the optic flow pattern improved the accuracy of subjects' perception of the distance travelled. However, no significant differences between biological and rhythmical oscillations were detected. These results relate to recent studies on the effects of smooth and jittering optic flows on vection onset and strength. One possible conclusion is that oscillations may increase the global retinal motion and thus improve the vection and path integration processes. Another possibility is that the nonmonotonous pattern of retinal motion induced by oscillatory inputs may maintain optimum sensitivity to the optic flow over time and thus improve the accuracy of subjects' perception of the distance travelled.

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

“…In the first experiment, static observers had to carry out a distance travelled estimation task while facing either a purely linear visual simulation of self-motion (in depth) or one to which viewpoint oscillations directly based on their own head oscillations previously recorded during treadmill walking were added. Results confirm that the benefits of viewpoint oscillation are maintained in an HMD, as established as in our previous studies conducted in a CAVE system (Bossard et al 2016;Bossard and Mestre 2018). The second experiment was designed to test whether the absence of viewpoint oscillations during treadmill walking (when visual consequences of the head translations generated by walking are deleted; non-oscillatory condition) affects subjects' perception of self-motion in comparison with a more complete pattern of visual feedback other dynamic cues.…”

“…On the tunnel floor, the subject could see a target, a "roadworks" beacon of the usual size (height: 70 cm). This target was placed at initial virtual distances of 6, 12, 18, 24 or 30 m relative to the observer, depending on the trial (Bossard et al 2016;Bossard and Mestre 2018;Plumert et al 2005).…”

“…On similar lines, we previously tested whether the perception of distance travelled was also affected by similar viewpoint oscillations to those induced by head motion during natural walking. In a preliminary series of experiments (Bossard et al 2016), we observed that in comparison with a purely translational optic flow, additional viewpoint oscillations simulating the head oscillations that occur during natural walking (using a model presented by Lécuyer et al 2006) improved the subjects' estimation of the distance travelled in a large-scale immersive display (CAVE). The main conclusion reached on the basis of these experiments was that this effect may be due to an increase in the global retinal motion.…”

Eye movements during path integration

“…, ; Bossard et al. ). Radial optic flow elicits a nystagmus‐like pattern of slow and fast conjugate eye movements (Niemann et al.…”

“…Movement of an observer through an environment generates a visual flow field on the retina. The properties of this flow field were shown to provide important cues for the estimation of parameters of self-motion, such as direction (heading), speed, and traveled distance, i.e., path integration (Gibson 1950;Andersen et al 1993;Lappe and Rauschecker 1994;Lappe et al 1996Lappe et al , 1999Bossard et al 2016). Radial optic flow elicits a nystagmus-like pattern of slow and fast conjugate eye movements (Niemann et al 1999).…”