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Abstract

Recent work indicates that the central nervous system forms multisensory perceptions differently depending on inferred signal causality. In accordance with these findings, we hypothesize that multisensory perception of traveled distance in the horizontal plane conforms to such Causal Inference (CI). Participants (n=13) were seated in the Max Planck Cablerobot Simulator, and shown a photo-realistic rendering of the simulator hall via a Head-Mounted Display. Using this setup, they were presented various unisensory and (incongruent) multisensory visual-inertial horizontal linear surge motions, differing only in amplitude (i.e., distance). Participants performed both a Magnitude Estimation and a Two-Interval Forced Choice task. We modeled the responses in the tasks according to a CI model, as well as competing models (Cue Capture, Forced Fusion), and compared the models based on their fits. The data indicate that distance is somewhat underestimated for both the visual and inertial unisensory channels, and that differential thresholds increase with physical distance -in accordance with a Weber’s law. Preliminary findings on model comparisons favor different models in different individuals, with an overall preference for the CI model. However, the data also suggest that different priors may be needed to account for differences between the tasks.