And this, we are beginning to realize, is a much more common occurrence than anyone had thought. More recently, psychologists have done substantial research on what is known as choice blindness, which, as its name suggests, is a kind of inability to “see” a decision. The lack of perception in question doesn’t have to do with aspects of a choice in progress, however, but with the nature of a choice already made: We literally cannot perceive what it is that we have chosen. In the best-known experiment on this phenomenon, the Swedish researchers Petter Johansson and Lars Hall gave a group of volunteers a series of paired photographs of female faces and asked the subjects to pick which woman in each pair they found more attractive. The researchers would then show the subjects the same card they had just chosen, and in some cases the subject would be asked to supply reasons for his or her decision. Each person looked at fifteen pairs of faces and made fifteen choices—but for three of the pairs, the researchers used a card trick to switch the faces after the volunteer’s selection. So in effect, the chooser was given the opposite of the choice he or she had actually made.