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 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 sound localization after exposure to spatially discrepant stimuli. The relationship between these processes - whether recalibration is a direct consequence of integration or operates independently - remains debated. This study investigates the role of causal inference in these processes by examining whether trial-wise judgments of audio-visual stimuli as originating from a common cause influence both the ventriloquism effect and the immediate aftereffect. Using a spatial paradigm, participants made explicit judgments about the common cause of stimulus pairs, and their influence on both perceptual biases was assessed. Our results indicate that while multisensory integration is contingent on common cause judgments, 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 byproduct of integration.