Multi-sensory integration is a process in which sensory input from one sense organ interacts with and influences how other sense organs process this same input, and how these inputs combine to produce a cohesive and unified perceptual experience (Talsma, Senkowski, Soto-Faraco, and Woldorff, 2010). A prime example of multi-sensory integration is the process of speech perception which combines auditory and visual inputs to form a cohesive and comprehensive speech percept (Nath and Beauchamp, 2012). In their 1976 article ‘Hearing Lips and Seeing Voices’, Harry McGurk and John MacDonald described a perceptual phenomenon they referred to as ‘the McGurk effect’ (McGurk and MacDonald, 1976). The McGurk effect is an audiovisual illusion that is…show more content… These McGurk and MacDonald studies were the first to demonstrate that visual stimuli can modify speech perception when it is presented simultaneously with incongruent auditory stimuli. These findings contested the traditional assumption that speech perception in face-to-face conversation was a unimodal, rather than multi-sensory process, that is, a strictly auditory process that was independent of visual input (McGurk and MacDonald, 1976; Rouger, Fraysse, Degunie and Barone, 2007; MacDonald and McGurk, 1978). Although McGurk and McDonald provided valuable insight into the role of visual processes in speech perception, their initial studies did have some limitations, for example, their manner-place hypothesis failed to provide a comprehensive theory of the cognitive processes involved in producing the McGurk effect. They also failed to measure their participant’s lipreading performances prior to conducting their study and thus, this potential confounding variable was not taken into consideration. Furthermore, McGurk and MacDonald failed to explain why up to one third of their participants did not experience the McGurk effect at all.
Since these original McGurk effect studies, there has been some debate between theorists and researchers,