You are hopeless at noticing change
In 1998 Simons and Levin performed an experiment to show just how bad people are at noticing change. A person with a map would approach someone, acting lost, and ask them how to get to somewhere. Whilst that person (an inadvertent participant in the experiment) tried to describe the route a couple of people barged through holding a door.
With well practised choreography the person who had asked directions switched places with one of the door carriers, who then pretended to be the person who had asked questions. The inadvertent participant would continue giving directions, and 50% of the time did not notice that the other person had changed.
This experiment demonstrated outside of the lab something that had been shown just in laboratory conditions before – the fact that we are all hopeless at noticing change. It seems preposterous that we would not notice something major changing from one second to the next, right in front of us. Actually, though, it makes perfect sense.
Look around you now and see just how much there is to notice. Imagine how much brain power it would take to actually memorise all of your surroundings, because of course to notice something has changed you first have to remember what it was before. It would take an unfeasible amount of brain storage to remember just one snapshot of our surroundings, let alone every second of every hour of every day. And what would be the purpose of remembering what is right in front of us? To know what is there we only have to look.
It would make no sense at all to remember everything we perceive from one second to the next. So we don’t. And so we often don’t realise when something has changed. And we don’t remember what passers-by look like. And we make hopeless eyewitnesses.
Find out more about how the mind plays tricks on you and how your memory works by reading my books, Bias Beware and Memory Matters.
If you are reading this online, first follow this link and watch the video, then come back.
You would think that if you are looking in a particular direction then you see whatever is there, as long as it is light enough. Unfortunately not. Inattention blindness is the term given to the fact that we miss some things that we are looking directly at, simply because our attention is focused on something else. Daniel Simons and Christopher Chabris brought this phenomenon to the public with their basketball video, but it has been shown in other experiments too. The more focused your attention and concentration are, the more likely you are not to notice something unexpected.
The most obvious real-world situation where inattention blindness can have serious consequences is driving. You are fine if you are driving along a clear road in the daylight, which requires very little attention, whilst holding a conversation with a passenger. However, trying to negotiate a difficult, busy junction at night makes you pause the conversation because all of your attention is required for the driving. Your passenger realises this and shuts up so you can concentrate.
Scholl et al had their participants watch a screen and count the number of times various grey shapes bounced off the sides of the monitor. After a while a bright red shape moved across the screen and 30% of the participants didn’t notice it. That was classic inattentional blindness. Then the experimenters repeated the experiment with people who also had to carry on a conversation on a hands-free phone. The number who didn’t even see the bright red shape went up to 90%!
Someone on the other end of a phone call doesn’t know you are coming up to a tricky junction and that the conversation should be paused. They continue speaking, you feel you should continue to listen to them and respond appropriately. You are now so concentrated on trying to negotiate a tricky junction, whilst attending to the conversation, that you are far more likely (90% in that experiment!) not to notice the unexpected (a cyclist perhaps).
You may protest that you have never failed to notice anything before, but think about it. Unless you actually crashed into something, how would you know?