trouble4hire told me about this story. I thought it sounded fascinating, so I looked it up. I just finished reading it, and it IS fascinating. If you are at all curious about how the brain works, especially as regards sensory perception, you should read this. I put it all on one page so it doesn't have to be loaded over and over again.
http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_gawande?currentPage=all