Change Blindness

The Misconception: You are aware of everything coming into your brain from your eyes from moment to moment.

The Truth: The brain can’t keep up the total amount of information coming in from your eyes; your experience from moment to moment is edited for simplicity.

Change blindness is slightly different from inattentional blindness, where you are unable to see things happening just outside your attention. With change blindness, you don’t notice when things around you are altered to be drastically different than they were a moment ago.

You often miss large changes to your visual world from one moment to the next, but that’s not how it feels. It feels like you see everything, at all times, and you believe your memory and your perceptions are based on that totality of experience.

Ok, ready to go mad?

In this demonstration from the Irvine School of Social Sciences, one thing is changed from one photo to the other. You will see them back to back over and over again with a flash of white in between. Try to find it – but I warn you, this takes most people a long time to find.

Once you see, you can never go back to the state when you couldn’t see it.

Reality is generated by the brain based on the inputs coming in from your senses. You don’t get a raw feed from those inputs; instead, you get an edited version.

The best example of this is the person swap.

In an experiment conducted at Harvard, subjects had to approach a man and sign a consent form. He stood behind a tall desk, like at a hotel, and once they signed the form, the man behind the desk ducked under it to put away the form. Another man then stood up and handed them a packet of information. Many people didn’t realize it was a different person.

Don’t think this only works with fast changes. Researchers at the University of Illinois are able to gradually add changes to photos which go unnoticed by most people.

When it comes to seeing changes to the world around you, even big ones, you are not so smart.


The Invisible Gorilla (I highly recommend this book for further reading on this topic.)

Video of the person swap experiment at Harvard

Video of Derren Brown performing the person swap

Examples of slow changes