A glimpse of cognitive science. I finally found a video showing the Mc Gurk effect. The seminal paper about this topic is McGurk, H. & MacDonald, J. W. (1976). Hearing lips and seeing voices. Nature, 264, 746-748. According to Lawrence Rosenblum:

The 'Mc Gurk' effect demonstrates of how we all use visual speech information. The effect shows that we can't help but integrate visual speech into what we 'hear'. It shows that visual articulatory information is integrated into our perception of speech automatically and unconsciously. The syllable that we perceive depends on the strength of the auditory and visual information, and whether some compromise can be achieved.

There is a movie here go there, and follow these steps:

play the clip several times, alternating between looking at the talking head while listening, and listening with your eyes shut. Most adults (98%) think they are hearing "DA" - a so called "fused respons" - where the "D" is a result of an audio-visual illusion. In reality you are hearing the sound "BA", while you are seing the lip movements "GA".

Why do I blog this? just to show how the integration of visual information are important and sometimes confusing for our cognitive system!