![Mark Changizi: Why do we see illusions?](https://pi.tedcdn.com/r/talkstar-photos.s3.amazonaws.com/uploads/ee18f51a-d9f7-4c53-8c02-60b0fd91a1a7/84_illusion+(1).jpg?h=200)
Why can't our extremely complex eyes render simple optical illusions? Surprise, surprise -- it comes back to the brain, which has only evolved to encounter natural stimuli. At TEDYouth 2012, Mark Changizi explains how the brain reckons with optical illusions.[Directed by TED Media].