This is a 20 minute TED video, is says a lot about how our brains are more reactive and conditioned than just pure observers...which may account for many of our differences (political views for instance). The two minute video that follows it about a pollution tax is interesting too.
http://www.ted.com/talks/beau_lotto_optical_illusions_show_how_we_see.html
http://www.ted.com/talks/beau_lotto_optical_illusions_show_how_we_see.html