Z:gnu-www-ja-frank--e54db2-The purpose of the random term/en

The purpose of the random term was to make it impossible for a subject to infer from her total payment how any of the other subjects had played. It prevented both the possibility of inferring individual choices and also of inferring even group patterns of choice. Thus, unlike earlier prisoner's dilemma experiments, ours did not enable the subject to infer what happened even when each (or neither) of her partners defected.