A simple strategy, applicable to any sequential decision task or game (1), according to which the first decision or move is chosen arbitrarily, and thereafter, whenever a choice leads to reward or a satisfactory outcome the player repeats it on the following occasion, and whenever it leads to punishment or an unsatisfactory outcome the player switches to a different option on the following occasion. If applied to the minimal social situation, it leads to mutually rewarding choices after only three rounds. It amounts to an implementation of the law of effect. It was first suggested in 1962 by the US psychologist Harold H. Kelley (1921–2003) and several colleagues in the journal Psychological Monographs. It has also been called the Pavlov strategy because of its simple reflex properties.