Viewpoint oscillation frequency influences the perception of distance travelled from optic flow

  • Bossard Martin
  • Goulon Cedric
  • Mestre Daniel


In everyday life, humans and most animals need to navigate in their environment, which produces multiple sources of perceptual information, such as locomotor cues (i.e. proprioceptive, efference copy and vestibular cues) and optic flow. However, few studies focused on the role of the visual consequences of walking (bob, sway, and lunge head motion) on self-motion perception. In a previous study, in which static observers were confronted to a visual simulation of forward motion, we have shown that adding rhythmical components to an optic flow pattern improved the accuracy of subjects' travelled distance estimations, in comparison with a purely translational flow. These results were attributable to the fact that oscillations may increase the global retinal motion and thus improve vection. Another hypothesis was that, walking step frequency being a significant cue in speed perception, visual consequences of step frequency might be at the origin of better estimations.To test this, we used the same experimental procedure in which observers, immersed inside a 4-sided CAVE, had to indicate when they thought they had reached a previously seen target. We tested whether different oscillation frequencies would affect the perception of distance travelled. Observers were confronted with 4 conditions of optic flows simulating forward self-motion. The first condition was generated by purely translational optic flow, at constant speed. The three other conditions of flows were vertical triangular oscillations with three kinds of frequencies added to linear forward motion, at the same forward speed. Results show that two groups can be distinguished. Regarding the first group, as in the previous study, adding rhythmic components improves the perception of distance travelled. For the second group, the higher the frequency, the earlier the answers, suggesting that these subjects related the oscillation frequency to their step frequency and perceived themselves as moving faster. Meeting abstract presented at VSS 2017