Different time scales of common-cause evidence shape multisensory integration, recalibration and motor adaptation

Abstract

Perception engages the processes of integration, recalibration and sometimes motor adaptation to deal with discrepant multisensory stimuli. These processes supposedly deal with sensory discrepancies on different time scales, with integration reducing immediate ones and recalibration and motor adaptation reflecting the cumulative influence of their recent history. Importantly, whether discrepant signals are bound during perception is guided by the brains inference of whether they originate from a common cause. When combined, these two notions lead to the hypothesis that the different time scales on which integration and recalibration (or motor adaptation) operate are associated with different time scales of evidence of a common cause underlying two signals. We tested this prediction in a well-established visuo-motor paradigm, in which human participants performed visually guided hand movements. The kinematic correlation between hand and cursor movements indicates their common origin, allowing us to manipulate the common-cause evidence by this correlation between visual and proprioceptive signals. Specifically, we dissociated hand and cursor signals during individual movements while preserving their correlation across movement endpoints. Following our hypothesis, this manipulation reduced integration compared to a condition in which visual and proprioceptive signals were perfectly correlated. In contrast, recalibration and motor adaption were not affected. This supports the notion that multisensory integration and recalibration are guided by common-cause evidence but deal with sensory discrepancies on different time scales: while integration is prompted by local common-cause evidence and reduces immediate discrepancies instantaneously, recalibration and motor adaptation are prompted by global common-cause evidence and reduce persistent discrepancies.