The role of conflict processing in multisensory perception: behavioural and electroencephalography evidence

To form coherent multisensory perceptual representations, the brain must solve a causal inference problem: to decide if two sensory cues originated from the same event and should be combined, or if they came from different events and should be processed independently. According to current models of multisensory integration, during this process, the integrated (common cause) and segregated (different causes) internal perceptual models are entertained. In the present study, we propose that the causal inference process involves competition between these alternative perceptual models that engages the brain mechanisms of conflict processing. To test this hypothesis, we conducted two experiments, measuring reaction times (RTs) and electroencephalography, using an audiovisual ventriloquist illusion paradigm with varying degrees of intersensory disparities. Consistent with our hypotheses, incongruent trials led to slower RTs and higher fronto-medial theta power, both indicative of conflict. We also predicted that intermediate disparities would yield slower RTs and higher theta power when compared to congruent stimuli and to large disparities, owing to the steeper competition between causal models. Although this prediction was only validated in the RT study, both experiments displayed the anticipated trend. In conclusion, our findings suggest a potential involvement of the conflict mechanisms in multisensory integration of spatial information.This article is part of the theme issue 'Decision and control processes in multisensory perception'.

Automated summary

In order to form coherent multisensory perceptual representations, the brain must solve the causal inference problem by deciding whether sensory cues should be combined or processed independently. The present study proposes that this process involves competition between alternative perceptual models and engages conflict processing mechanisms in the brain. Two experiments were conducted to test this hypothesis, which measured reaction times and electroencephalography using an audiovisual ventriloquist illusion paradigm. The findings suggest a potential involvement of conflict mechanisms in the multisensory integration of spatial information.