Would you send someone to jail on the basis of video footage shot with a low-resolution camera whose lens has dirty marks around the sides and a massive hole in the middle? Probably not, and yet that is basically what eyewitness testimony is. While it looks like we see the world in vivid detail, like the display on a high-definition television, that’s largely because the information from our eyes is heavily processed by the brain. It covers the missing information in our blind spot, and smoothes over the lack of detail around the edges. It’s a filtered version of reality.

This is hardware problem, but the software has glitches too. Our view of the world is sensitive to our expectations, our desires and where we assign out attention. Simply put, we see what our brain wants us to see. The camera metaphor implies a passive process where we switch on our memory, and it dutifully records away. The reality is very different.