Magnitude Estimates of Angular Motion: Perception of Speed and Displacement Across Vestibular and Visual Modalities

Communication Sciences and Disorders Au.D.

Both the vestibular system (e.g. VOR) and optokinetic system (e.g. OKN) generate conjugate eye movements in response to either movement of the head or movement of the visual surround. Both systems help to maintain gaze stability. While the VOR is most sensitive to input frequencies above .2 Hz, the oculomotor system helps maintain gaze stability at lower frequencies. Psychophysics is the study of the relationship between perception and a physical stimulus. Previous research on perceptual thresholds across the two sensory modalities shows that there are frequency-dependent differences between vestibular and visual perception. The purpose of this study is to extend previous vestibular psychophysics work by measuring magnitude estimates of speed and angular displacement in response to suprathreshold stimulation from either vestibular or visual stimuli. Participants were exposed to 12 experimental conditions of angular rotation of varying frequencies, peak velocities, and acceleration rates across both sensory modalities. Vestibular stimulation was provided with a rotary chair and visual stimulation with equivalent conditions but under a virtual reality headset. Participants provided magnitude estimates of their speed and angle of displacement. Results reveal that vestibular and visual perception of suprathreshold motion stimuli differ as a function of frequency and agree with perceptual threshold data.