October 4, 2020


Choice blindness: Do you know yourself as well as you think? (David Edmonds, 10/04/20, BBC World Service)

Swedish experimental psychologist Petter Johansson loves magic. He's not formally trained but he's taught himself some basic sleight of hand techniques. Magicians have long understood the phenomenon of "change blindness". By distracting you, a magician can change a card, say the King of Clubs for the King of Spades, and the chances are you won't notice.

Johansson's rudimentary magic skills are useful for his experiments - for, some years ago, he and his colleagues decided to test not change blindness but "choice blindness".

Let me explain. In his earliest experiment, Petter Johansson showed participants pairs of pictures of faces. The subjects had a simple task: to choose the one they found most attractive. Then they were given the picture and asked to justify their selection. But unbeknown to them, Johansson had deployed his magic to make a switch; they were actually handed the picture of the man or woman they had not picked.

Petter Johansson showing a female participant two photographs of men
image captionPetter Johansson shows a female participant two photographs of men
You might assume that everyone would notice. If so, you would be wrong. Amazingly, only a quarter of people spot the switch. To repeat, the faces were of different people, and there were easily identifiable differences between them. One might be brown-haired and with earrings; the other might be blonde and with no earrings.

After the switch, the subjects explained why they had chosen the person they had actually not chosen! "When I asked them, why did you choose this face?" says Petter Johansson, "they started to elaborate on why this was the preferred face, even if, just a few seconds before, they had preferred the other face."

When he explained to them what he had done, he was usually met with surprise and often disbelief. The most intriguing cases were those in which people justified the manipulated choice by highlighting something absent in their original choice. "For instance, if they say, 'Oh, I prefer this face because I really like the earrings,' and the one they originally preferred didn't have any earrings, then we can be certain that whatever made them make this choice, it can't have been the earrings."

What can we conclude from this? Well, it turns out that we don't have a clear understanding of why we choose what we choose. We often have to figure it out for ourselves, just as we have to figure out the motives and reasons of others. The window through which we try to observe our own soul is dim and murky.

Our choices just don't much matter.

Posted by at October 4, 2020 12:00 AM