Our brains do a lot of calculations without us knowing. They use the timing of the light getting to our eyes, along with assumptions about light and sight, to work out where things are. This is really helpful, because it means that we know which things around us are closer than other things.
The brain fills things in using the information that it has, and makes best guesses, as you can see here. When the dot is in the blind spot, the brain fills in the space with what looks like blank paper, because that’s what is around it.
Our brain is constantly making conclusions about our body to protect us. In this case, the brain concludes that the dents in the finger must actually be on the pencil.
The brain puts information together to come to conclusions about the body. This illusion shows that the brain can easily come to the wrong conclusion about the body.
When the brain receives information that it is unclear, it has to work out what is going on. It uses previous experiences, context, and your beliefs to do this.
This demonstration shows how our awareness of something is based on our brain’s interpretation, instead of exactly what is going on in the world.
Without the goggles on, you naturally know quite well how to throw a beanbag and hit a target. However, when you put the prism goggles on, they shift what you can see to one side.