Dispensability of member effort and group motivation losses: Free-rider effects.

Three experiments tested the hypothesis that group members exert less effort as the perceived dispensability of their efforts for group success increases. The resultant motivation losses were termed "free-rider effects." In Exp I, 189 undergraduates of high or low ability performed in 2-, 4-, or 8-person groups at tasks with additive, conjunctive, or disjunctive demands. As predicted, member ability had opposite effects on effort under disjunctive and conjunctive task demands. The failure to obtain a relationship between group size and member effort in Exp I was attributed to a procedural artifact eliminated in Exp II (73 Ss). As predicted, as groups performing conjunctive and disjunctive tasks increased in size, member motivation declined. This was not a social loafing effect; group members were fully identifiable at every group size. Exp III (108 Ss) explored the role that performance feedback plays in informing group members of the dispensability of their efforts and encouraging free riding. Results are generally consistent with those of Exps I and II.