Social dilemmas, institutions, and the evolution of cooperation

Roger Berger and Bastian Baumeister

Repetition Effects in Laboratory Experiments

Abstract: Subjects of laboratory experiments are often recruited from a subject pool. Such experiments are typically similar in content and demand, and so learning processes can be assumed when the same subjects attend two subsequent experimental sessions. We label these “repetition effects”, because in these cases the learning processes differ from those where repeated decisions are made within a singular experiment. Such repetition effects endanger the validity of laboratory experiments. Repetition effects have a procedural component (subjects get to know procedures and equipment in the lab) and a social component (subjects learn how to interact within the special ...