If your ears register /ba/ and your eyes a mouth saying /ga/, you’ll “hear” /da/. It’s called the McGurk effect:

The most striking demonstration of the combined (bimodal) nature of speech understanding appeared by accident. Harry McGurk, a senior developmental psychologist at the University of Surrey in England, and his research assistant John MacDonald were studying how infants perceive speech during different periods of development. For example, they placed a videotape of a mother talking in one location while the sound of her voice played in another. For some reason, they asked their recording technician to create a videotape with the audio syllable “ba” dubbed onto a visual “ga.” When they played the tape, McGurk and McDonald perceived “da.” Confusion reigned until they realized that “da” resulted from a quirk in human perception, not an error on the technician’s part. After testing children and adults with the dubbed tape, the psychologists reported this phenomenon in a 1976 paper humorously titled “Hearing Lips and Seeing Voices,” a landmark in the field of human sensory integration. This audio-visual illusion has become known as the McGurk effect or McGurk illusion.

Amazing. (Via Sally Thomason at Language Log.)


  1. This website has a video demo of the McGurk effect.

  2. aldiboronti says

    Astonishing! It really does work. Shut your eyes and listen, you hear “baba”. Look at the video, and it changes to “dada”.
    What I’m attempting now is to quickly open my eyes in the middle of a “baba” and catch the illusion with its pants down.

  3. Frances Tongcos says

    hi! im a senior psychology major at the University of the Philippines – Diliman and we will be doing a study on McGurk effect in Filipino language. As we all know, McGurk effect has been observed in different countries in the world already and me and my co-researchers for our perception course would like to see whether there is McGurk effect in our language. I would really appreciate those who would like to help us find articles which we can use for our literature review..thank you so much.

  4. Good luck with the study, and I hope you’ll drop by and let us know the results!

  5. Sorry for my links
    [I deleted a couple of dozen porn links, but I couldn’t bring myself to delete the obsequiously brazen, or brazenly obsequious, “Sorry for my links”: talk about chutzpah! — LH]

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