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Abstract

We investigated how optic flow and physical body movements are integrated in the perception of upright self-rotation. In sensor fusion experiments, large intersensory conflicts often lead to bimodal response distributions (ie response is dominated by any one of the input modalities). We hypothesised that the selection of dominant modality can be controlled by attention.
Subjects were rotated by means of a Stewart motion platform. Optic flow stimuli were presented on a video projection screen. For each trial, first a concurrent rotation of the platform and the visual stimulus was presented. Subjects were then asked to reproduce either the perceived visual rotation or the perceived platform rotation using a joystick. During rotation reproduction, a gain factor between the rotation speeds of the two cues was applied. The results show that visual cues exert a greater influence on the vestibularly reproduced rotation than vice versa. When the difference between visual and platform rotation was great, response distributions for each of the two attentional conditions were unimodal, but the means of the distributions of these two conditions differed significantly from each other. This shows that the fused, unimodal percept can be shifted by an attentional bias toward the attended cue.