He discusses his book here with Stephen Colbert in this video
His expriments are similar to the experiments conducted by Yale Psychologist Stanely Milgram in which he studied the willingness of the subjects to obey the authority figures.
An excerpt from an article by Stanely Milgram
The Perils of Obedience
Obedience is as basic an element in the structure of social life as one can point to. Some system of authority is a requirement of all communal living, and it is only the person dwelling in isolation who is not forced to respond, with defiance or submission, to the commands of others. For many people, obedience is a deeply ingrained behavior tendency, indeed a potent impulse overriding training in ethics, sympathy, and moral conduct.
The dilemma inherent in submission to authority is ancient, as old as the story of Abraham, and the question of whether one should obey when commands conflict with conscience has been argued by Plato, dramatized in Antigone, and treated to philosophic analysis in almost every historical epoch. Conservative philosophers argue that the very fabric of society is threatened by disobedience, while humanists stress the primacy of the individual conscience.
The legal and philosophic aspects of obedience are of enormous import, but they say very little about how most people behave in concrete situations. I set up a simple experiment at Yale University to test how much pain an ordinary citizen would inflict on another person simply because he was ordered to by an experimental scientist. Stark authority was pitted against the subjects' strongest moral imperatives against hurting others, and, with the subjects' ears ringing with the screams of the victims, authority won more often than not. The extreme willingness of adults to go to almost any lengths on the command of an authority constitutes the chief finding of the study and the fact most urgently demanding explanation. Source