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Abstract:
Numerous studies report that humans integrate multisensory information in a statistically optimal fashion. However, with respect to self-motion perception, results are inconclusive. Here we test the hypothesis that visual and inertial cues in simulator environments are optimally integrated and that this integration develops over time. Eight participants performed a 2AFC discrimination experiment in visual-only, inertial-only and visual-inertial conditions. Conditions were repeated three times. Inertial motion stimuli were one-period 0.5 Hz sinusoidal acceleration profiles. Visual stimuli were videos of a vertical stripe pattern synchronized with inertial motion. Stimuli were presented in pairs with different peak velocity amplitudes. Participants judged which rotation of a pair had the highest velocity. Precision estimates were derived from psychometric functions. Optimal integration predicts improved precision in the combined condition. However, precision did not differ between the visual and combined conditions. This suggests that participants based their responses predominantly on visual motion. Alternatively, the results could be consistent with optimal integration if the assumption that visual precision remains unchanged during inertial motion was violated. We suggest that a change in visual sensitivity should be considered when investigating optimal integration of visual and inertial cues.
