Velocity influences the relative contributions of visual and vestibular cues to self-acceleration.

Abstract

Self-motion perception is based on the integration of visual (optic flow) and vestibular (inertial) sensory information. Previous research has shown that the relative contribution of visual and vestibular cues can change in real time based on the reliability of that information. The present study assessed whether initial velocity and acceleration magnitude influence the relative contribution of these cues to the detection of self-acceleration. Participants performed a simple response time task with visual and vestibular self-acceleration cues as targets. Visual optic flow was presented at three possible initial velocities of 3, 9, or 15m/s, and accelerated to result in three possible final velocities of 21, 27, or 33m/s. Corresponding vestibular cues were presented at magnitudes between 0.01 and 0.04g. The self-acceleration cues were presented at three possible stimulus onset asynchronies (SOAs): visual-first (by 100ms), in-sync, and vestibular-first (by 100ms). We found that presenting the cues in-sync resulted in the fastest responses across all velocities and acceleration magnitudes. Interestingly, presenting the visual cue first resulted in a relative advantage over vestibular-first at the slowest initial velocity of 3m/s, and vice versa for the fastest initial velocity of 15m/s. The fastest overall responses for visual-first and in-sync were observed at 9m/s. The present results support the hypothesis that velocity of optic flow can alter the relative contribution of visual and vestibular cues to the detection of self-acceleration.