The McGurk effect is a powerful illusion where our brains hear the wrong noise if they're presented with visual evidence that something else is being said. Now we've discovered what part of the brain is behind this strange effect.
We've already talked about optical illusions, but this auditory illusion might be even freakier. Let's say you record a person pronouncing a couple sounds over and over again - say, "bah" and "vah", which are very similar sounds made with clearly different lip movements. Now you keep the audio of the person saying "bah" but overlay it with the video of the person saying "vah." Which sound will you hear?