Would you notice whether the person you were talking to had been swapped for a new person?
When you watch this multimedia exhibit video… you’ll see how a man doesn’t realise that he’s talking to two different people who had swapped places. It’s commonly known as change blindness.
Illusionists and magicians sometimes rely on covert misdirection which is a form of change blindness to perform their tricks.
Spectators can be staring directly at what the magician is doing, but a subtle dimming of lights or falling covers can create enough disruption so people fail to notice any changes between the before and after scene.
This exhibit’s video was filmed and donated by Professor Daniel Simons and Daniel Levin (1998) as part of a scientific experiment about ‘change blindness’ in social situations. You can view it at their web site.
In this video, an experimenter stops a ‘Passer-by’ to ask for directions. Suddenly, two other men barge through, carrying a door (the door interruption).
The Experimenter swaps places with a second Experimenter behind the door and resumes the conversation with the Passer-by when the door is gone.
But the Passer-by doesn’t realise that he is now talking to a different man!
People who watch the video tend to be amazed that the Passer-by doesn’t notice that he’s talking to a different man.
In the scientific study, about 50% of the Passers-by had no idea that they were talking to a different person after the door interruption, even though the two Experimenters who swapped places behind the door were different height, had distinct voices, and wore different clothing.
Passers-by who did notice the swap tended to be students and were from the same social ‘in-group' as the Experimenters.
When you look at a scene, you can’t possibly memorise or store every detail of what’s there. So, you can’t compare what you’re seeing now with what you saw before.
So, when you’re distracted or interrupted by something (like a flickering screen or a door!), you’re forced to compare two scenes from memory (even it was just half a second ago), rather than noticing a change as it happens.