The McGurk Effect

The McGurk effect is a perceptual phenomenon that demonstrates the interaction between hearing and vision in speech perception. He suggests that speech perception is multimodal, that is, it involves information from several senses at once. The MacGurk effect is also sometimes called the MacGurk - Mac Donald effect. It was first described by McGurk and Mac Donald in 1976.

This effect can be experienced when watching a video with a video sequence with one phoneme and sound track with the pronunciation of another phoneme. Often the perceived phoneme is the third, middle between the two. For example, in the original McGurk experiment, the subjects were shown a video of a man who repeatedly pronounced ga-ga syllables with his lips, while the phonogram reproduced ba-ba syllables. When the subjects closed their eyes and only listened to the phonogram, they accurately recognized syllables. Moreover, when they saw only the movements of the lips of the talking person, and the phonogram was turned off, they accurately identified the pronounced sounds as ga-ga (thereby confirming that we can read lips if necessary and that we can do this much more often, than it seems to us). However, when the subjects were simultaneously presented with conflicting auditory and visual stimuli, they heard sounds that were not present in any of them. For example, when the subjects saw on the screen a person whose lip articulation corresponded to ga-ga syllables, and at the same time the acoustic signal ba-ba sounded, most of them heard a completely different sound - da-da, while most of the subjects did not realize the mismatch between auditory and visual stimulations . Subsequent experiments showed that a similar effect is observed when conducting experiments with whole sentences. The effect is very stable, and knowledge of it almost does not affect its perception, which is different from some optical illusions that are destroyed by careful study.

Studying the McGurk effect is used to create more accurate speech recognition programs using a video camera and lip - reading software . A 2005 study by Weiram and Wright showed that the McGurk effect can have a big impact on everyday perception.