McGurk Effect

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The McGurk effect is the influence on the perception of an acoustic speech signal through the simultaneous observation of a lip movement or unconscious lip reading . This audio-visual illusion is considered a milestone in perceptual psychology and proof of the integration of visual impressions into speech perception.


In the classic experimental setup, a test person is shown a video tape on which a person can be "seen" who utters the syllables / ga-ga / . However, the audio track of the video tape was manipulated and lets the test subjects “hear” the syllables / ba-ba / . About 98 percent of the adult test persons stated that they “noticed” the syllables / da-da / .

Explanatory approach

According to the motor theory of speech perception , our brain tries to use all signals, including the optical information, in order to discover how the acoustic signal was generated. Since our memory says that there is a direct connection between lip movement and sounds, the visual information of the lip movement has a great influence on the processing unit for phonemes in our brain. The language center apparently combines the contradicting sensory impressions in order to correct them, thus creating a new virtual impression.


In the mid- 1970s , developmental psychologist Harry McGurk (1936–1998) and his colleagues at the University of Surrey near Guildford discovered the effect rather accidentally while they were investigating perception in young children.

Due to the publication of the results in Nature (1976) and the associated high level of attention, numerous experiments were carried out according to a similar pattern: The effect was checked in different languages, some studies looked at the effect on children, others examined whether similar results occur with non-speech sound signals .

However, a reduction in the effect was found for languages ​​such as standard Chinese and Japanese.


  • McGurk, Harry and Macdonald, John: Hearing Lips and seeing voices . In: Nature . tape 264 , 1976, pp. 746-748 , doi : 10.1038 / 264746a0 .
  • Macdonald, John and McGurk, Harry: Visual influences on speech perception processes . In: Perception and Psychophysics . tape 24 , 1978, p. 253-257 , doi : 10.3758 / BF03206096 .
  • Grassegger, Hans: McGurk effect in German and Hungarian listeners . In: Proceedings of the XIIIth International Congress of Phonetic Sciences . tape 3 , 1995, ISBN 91-7170-839-1 , pp. 210-213 .

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