The context of experienced sensory discrepancies shapes multisensory integration and recalibration differently

Whether two sensory cues interact during perceptual judgements depends not only on their immediate properties, but also the overall context in which these are encountered. While in many experiments this context is fixed, in real life multisensory perception must adapt to the momentary environment. To understand the adaptive nature of human multisensory perception we investigated spatial judgements in a ventriloquism paradigm: on different days we exposed observers to audio-visual stimuli whose discrepancy either varied over a wider (± 46°) or a narrower range (± 26°) and hypothesized that exposure to a wider range would foster the multisensory binding of these signals. Our data support this hypothesis by revealing an enhanced integration (ventriloquism) bias in the wider context. Results from Bayesian modelling suggest that this may arise from changes in the a priori integration tendency and changes in spatial attention. Interestingly, the immediate ventriloquism aftereffect, a multisensory response bias obtained following a multisensory test trial, was not affected by the contextual manipulation, although participants' confidence in their spatial judgements differed between contexts both for integration and recalibration trials. These results highlight the context-sensitivity of multisensory binding and suggest that the immediate ventriloquism aftereffect is not a purely sensory-level consequence of a previous multisensory integration process.