The nudge theory and beyond: how people can play with your mind

Mental manipulation can be backed by good intentions - but when used with stealth, it is deceitful and wrong

A couple of decades ago, a class of psychology undergraduates played a mean trick on their lecturer. The students on the right side of the room gently nodded, smiled, and looked thoughtful, while those on the left seemed bored and glum. Before long, the unsuspecting lecturer was addressing the "right" students with enthusiasm, with only the odd uncomfortable glance to the rest. On some secret sign, the students changed roles - and the lecturer duly switched to addressing students to the left. Memories are vague on how often the hapless lecturer was pushed to and fro.

The students' hilarity was no doubt considerable, especially as the trick used one of the key principles they were being taught: that pigeons, rats or lecturers do more of what is rewarded, and less of what is punished. But how did the lecturer feel when the trick was revealed? In his shoes, I imagine myself trying to summon a brave laugh, but feeling pretty dreadful. Even where no malice is intended, the sense of having been manipulated is hurtful indeed.