Illusory Self-Motion Affects Time Processing in Human: an Exploratory Study

Movement influences perception, and passive self-motion can modulate time per-ception. This exploratory study tested whether linear vection (visually induced illusory self-motion) affects time perception. Spontaneous Motor Tempo (SMT) was measured in 20 young healthy participants seated in a small cabin, viewing peripheral optokinetic stripes that either remained static (reference) or moved along sagittal or vertical direction. Vection trials (VEC) were compared to visually identical optokinetic trials delivered in dim light that sup-pressed vection (OPTO), plus DARK and LIGHT static controls. Eight different optokinetic stimulations were used, resulting from the combination of 4 directions (Forward, Backward, Upward, Downward) x 2 velocities (Slow – Fast). When vection occurred, its onset latency was recorded. Linear mixed-effects models revealed significant effects of all manipulated fac-tors on inter-response intervals (IRI), with individual variability accounting for a large part of the variance. Results showed a trend toward faster tempo in fast and vertical VEC condi-tions, those with shorter vection latencies. Based on the observation of vection latencies dif-ferences and on the improvement of tapping regularity with visual motion, results are dis-cussed in terms of relative effects of the self-motion sensation, presence of visual optokinetic stimulation and experimental environment.