Velocity perception in a moving observer.
Previous research has shown that when a moving stimulus is presented to a moving observer, the perceived speed of the stimulus is affected by vestibular self-motion signals (Hogendoorn, Verstraten, MacDougall, & Alais, 2017. Vision Research 130, 22-30.). This interaction was interpreted as a weighted sum of visual and vestibular motion signals. This interpretation also predicts effects of vestibular self-motion signals on perceived speed. Here, we test this prediction in two experiments. In Experiment 1, moving observers carried out a visual speed discrimination task in order to establish points of subjective equality (PSE) between stimuli presented in the same or opposite direction of self-motion. We observed robust effects of self-motion on perceived speed, with self-motion in the same direction as visual motion resulting in increases in perceived speed and vice versa. These effects were well- described by a limited-width integration window. In Experiment 2, the same observers carried out another speed discrimination task in order to establish discrimination thresholds. According to the Weber-Fechner law, these thresholds are expected to increase or decrease along with perceived speed. However, no effect of self-motion on discrimination thresholds was observed. This pattern of results suggests a limit on speed discrimination performance early in the visual system, with visuo-vestibular integration in later downstream areas. These results are consistent with previous work on heading perception.
['Hogendoorn|Hinze|H|', 'Alais|David|D|', 'MacDougall|Hamish|H|', 'Verstraten|Frans A J|FAJ|']
D004192:Discrimination, Psychological D005260:Female D006801:Humans D008297:Male D009039:Motion Perception D009068:Movement D012684:Sensory Thresholds D014722:Vestibule, Labyrinth
Vestibular Self-motion Visual motion Speed perception