We have all experienced it with movies, series, music videos, and even live television: someone is speaking, we watch them while they talk, and we believe we heard a specific word... but the movement of their lips doesn't quite match Welcome to the McGurk effect, a phenomenon that can distort speech perception. In other words, the “feedback” received through the eyes can place sounds in our ears that were never actually reproduced.
Some people are especially clear when speaking. Others carry such a heavy, marked accent that we almost need subtitles. And then there are those who seem to say something... and actually say something else. It's a simple matter of receiving data and interpreting it incorrectly. A great example is optical illusions, which generally make us see things that don't exist, but guess what? The eyes-brain relationship can install sounds in our ears that were never emitted. The official name for that auditory illusion is the “McGurk effect”
The McGurk Effect: When Eyes Take Priority
In the first video, the young woman is repeating the word “bar”. It sounds like “bar”, and our eyes seem to confirm through the movement of her lips that it is indeed “bar”. Now, when we play the second video, the combination of ears-eyes-brain indicates that the word being repeated is “far”... but that's an error: what she says is “bar”, just like in the first video.
The McGurk effect is compelling proof of the conflict that arises between two sensory systems when they interpret the same information, and the influence of one over the other. In this case, the eyes gain priority over the ears.
The most effective way to counteract the McGurk effect is closing your eyes, leaving the path clear for auditory processing. Another striking detail is that our knowledge of the McGurk effect does not minimize its impact; it works perfectly every time. The human brain does its best to resolve sensory differences, and on certain occasions, its result is far from optimal...
