An interesting Science paper from 2005 was recently featured on the Futility Closet blog, offering a look at both an interesting experimental protocol and the psychological phenomenon it exposed, choice blindness. Basically, research subjects were shown photographs of two people and asked to choose which they found to be more attractive. They were then handed the photo they chose and asked to explain why they found that person more attractive. The experimenter used sleight-of-hand techniques, however, to switch the photos, and what they were actually handed was the image of the person they didn’t choose. The majority of research subjects did not notice the switch, and went ahead and created a rationale for why the non-chosen image was the more attractive one.
A similar experiment was done with a taste test of different jams. The subject chose their favorite, which was then switched with the one they didn’t choose, and they then explained why the non-chosen jam was superior.
These are both great examples of choice supportive bias, or post-purchase rationalization. It explains a lot about how unreliable online product reviews can be. We all want to feel we made the right choice, even if this requires some level of self-deception in retroactively justifying that choice. Also, this would be a difficult experiment to reproduce — think of how much training in close-up magic a graduate student would need.