Do we see everything happening in front of our eyes? [All Ages]
Does the brain process everything that you see?
We are only ever aware of a small part of the world around us. We need attention to pick out the most important aspects of the world and bind them together into a meaningful story. However, if we are not paying attention then we can easily miss things that happen right in front of our eyes.
Play the following video and ask the audience to shout out when they notice the changes between shots. Pause the video at 0:27.
The audience probably found that quite difficult. Now play them the rest of the video which shows the same set of images without the blank screen in between.
This time round the changes should have been much more obvious. Without attention we are blind to the world around us. The first video is a very good example of how we can miss quite big changes even when we are looking for them.
Q: Why was it difficult to see the changes in the first video.
A: It was difficult to see the changes in the first video because you are not sure where in the picture to focus your attention because the changes could happen anywhere. Although we feel like we are looking at all of the image at once, we are actually just focusing on a series of very small parts of it. If the change happens in a part that we are not focusing on then we don’t see it.
Q: Why was it easier to see the changes in the second video?
A: The blank screen in between shots in the first video acts like a blink – each time it happens we recreate our mental representation of the image in our mind. When there is no blink, the changes in the scene attract our attention because they look like movement within the picture so our eyes go straight to them.
In-attentional Blindness: The Gorilla in our midst [Key Stages 2-4]
Is it possible to miss things that are happening right in front of your eyes?
We can focus our attention on a very small part of the world, even ignoring other things that are happening in almost exactly the same space. In this clip there are a number of professional jugglers. Ask the audience to use their attention to count the number of times that the black baton is passed between jugglers and ignore all the times that the white baton is passed. Tell them its quite difficult so please concentrate very hard and only count in their heads, not out loud. Pause the video at 2:08.
Ask the audience how many times the black baton was passed.
Ask the audience to put their hands up if they saw Bruce take off his hat or his jacket.
Ask the audience to put their hands up if they saw anything else. Some hands will go up but most people will have missed the gorilla.
Play the rest of the video which shows the audience’s response and a slow-motion re-enactment of the gorilla walking behind the jugglers.
Q: Why did some people not see the gorilla?
A: Some people didn’t see the gorilla because they were focusing so hard on the batons that they ignored everything else that was going on in the scene, even though it passed straight through the part of the world that they were looking at!
Q: Why does the brain filter out the gorilla?
A: There is a constant stream of information coming in through the senses and one of the most important jobs the brain does is to filter in just those bits of information that are important and ignore the rest. Of the bits that the brain attends to, only a small amount then gets fed into conscious awareness. This means that your eyes might have seen the gorilla but your brain filtered out this information because it didn’t think it was important to the task of counting how many times the black baton was thrown.