Multisensory integration processes underlying speech perception as revealed by the McGurk illusion

The McGurk illusion is one of the most studied illusions in the multisensory integration literature. It is based on the synchronous presentation of visual lip movement, accompanied by a different auditory syllable resulting in the perception of a third syllable. This illusion provides information regarding the unconscious integration of input from different sensory modalities involved in speech perception. Here, we present a review of the use of the McGurk illusion as a tool for the understanding of multisensory integration processes involved in speech perception. This review intends to provide a better knowledge of the McGurk illusion and the multisensory integration processes involved in speech perception. Also, considering the robustness of the illusion and the insights it provides on multisensory integration processes, we present possible uses of the illusion as a tool to investigate multisensory integration in clinical populations.