Perceived Multisensory Common Cause Relations Shape the Ventriloquism Effect but Only Marginally the Trial-Wise Aftereffect.

Combining multisensory cues is fundamental for perception and action and reflected by two frequently studied phenomena: multisensory integration and sensory recalibration. In the context of audio-visual spatial signals, these phenomena are exemplified by the ventriloquism effect and its aftereffect. The ventriloquism effect occurs when the perceived location of a sound is biased by a concurrent visual stimulus, while the aftereffect manifests as a recalibration of perceived sound location after exposure to spatially discrepant stimuli. The relationship between these processes-whether recalibration is a direct consequence of integration or operates independently-remains debated. We investigate the role of causal inference in these processes by examining whether trial-wise judgements about a common-cause underlying audio-visual stimuli influence both the ventriloquism effect and the immediate aftereffect. In a spatial paradigm, participants made explicit judgements about the common cause of stimulus pairs, and their influence on both perceptual biases was assessed. Results obtained across two experiments indicate that while multisensory integration is contingent on common cause judgements, the immediate recalibration effect is not. This suggests that recalibration can occur independently of the perceived commonality of the multisensory stimuli, challenging the notion that recalibration is solely a by-product of integration.