A classic 1959 experiment by Aronson and Mills demonstrated the justification of effort effect. College students volunteered to join a campus group discussing the psychology of sex and were randomly assigned to one of three initiation conditions: no initiation, an easy initiation, or a difficult initiation. After taking part in an intentionally boring first discussion, the participants rated their liking of the group. The results, as illustrated in the accompanying bar graph, showed that individuals who endured a difficult initiation rated the group significantly more favorably than those who experienced an easy or no initiation.