Watch the following clip and listen to the sound that the man is making. Most people think he is saying ‘da-da, da-da’. Watch it again this time with your eyes closed. You may hear something different; ‘ba-ba, ba-ba’. This is called the McGurk effect.
It appears that we ‘hear’ different things depending on how many of our senses are available to us (sound only; or sight and sound). The implication is that without us realizing that it is doing so, our brain actively interprets the sense data it receives. In this instance what we see shpaes what we hear. What implications might this have for our knowledge gained through sense perception? If what we see dominates what we hear, does it follow that we cannot trust our senses?