Suggestion overrides automatic audiovisual integration

•We investigate whether suggestion can de-automatize audiovisual integration in speech perception.•Ten highly and ten less hypnotically suggestible individuals perform the classic McGurk task.•We provide a posthypnotic suggestion to prioritize the auditory input whilst crisply viewing the video.•Posthypnotic suggestion reduces McGurk illusions in highly but not less suggestible individuals.•We show that suggestion overrides the automaticity of audiovisual speech perception.

Cognitive scientists routinely distinguish between controlled and automatic mental processes. Through learning, practice, and exposure, controlled processes can become automatic; however, whether automatic processes can become deautomatized – recuperated under the purview of control – remains unclear. Here we show that a suggestion derails a deeply ingrained process involving involuntary audiovisual integration. We compared the performance of highly versus less hypnotically suggestible individuals (HSIs versus LSIs) in a classic McGurk paradigm – a perceptual illusion task demonstrating the influence of visual facial movements on auditory speech percepts. Following a posthypnotic suggestion to prioritize auditory input, HSIs but not LSIs manifested fewer illusory auditory perceptions and correctly identified more auditory percepts. Our findings demonstrate that a suggestion deautomatized a ballistic audiovisual process in HSIs. In addition to guiding our knowledge regarding theories and mechanisms of automaticity, the present findings pave the road to a more scientific understanding of top-down effects and multisensory integration.