The McGurk effect

            
             The experiment aimed to discover if real words actually could be used to cause a McGurk effect. Easton and Basala (1982) claimed the McGurk effect probably wouldn't materialise using recognised words instead of motherese. Pisoni and Luce (1986) concluded that the McGurk effect was due to a simple bias effect. The experimental design was a repeated-measure and used a voluntary sample of 12 participants. Audio and audio-visual plus audio stimuli were both presented 66 times using a tape recording alone or partnered with a person miming a word for the two conditions. These conditions were counterbalanced. The phrase presented was either recognised as oh dear or oh beer. There were eleven variations of the phrase with each only being presented six times. These variations were produced through mixing beer and dear using a wavelength editor. Before the tape was made all the mixed and not mixed phrases were randomised to guard against order effects. It was believed that audio-visual stimulus had a strong influence on speech perception. This hypothesis was statistically supported by p. < 0.001. Both the theories mentioned above were supported through analysis of the data leading to the belief that the McGurk effect is caused by a simple bias effect.
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             Introduction.
             McGurk (1976) accidentally discovered the phenomenon of the McGurk effect that is also known as audio-visual speech perception. McGurk discovered that visual information had a strong influence on the process of speech perception. Visual information in this instance is concerned with the movements of the lips. This is generally recognised as lip reading. Speech perception is what is heard. He made his discovery whilst setting up an experiment to investigate "ability of infants to integrate auditory and visual information" (Watkins, 2003). McGurk was checking his stimuli and incorrectly discovered the replaced words were incorrect yet when he closed his eyes they were correct.