To demonstrate that the potential for self-evaluation can motivate performance, the potential for evaluation by external sources must be eliminated. As Bandura (1986) writes, "When environmental constraints are reduced, the influence of self-evaluative motivators becomes most self-evident" (p. 479). Thus, to determine whether the self-evaluative concerns suggested by social comparison theory motivate performance, one must ensure that people feel that they cannot be individually evaluated by an externalsource. Such control of external evaluation is made possible through the use of the social loafing paradigm (e.g., Latane, Williams, & Harkins, 1979). Social loafing refers to the finding that people put out less effort when working together than when working alone (Latane, Williams, & Harkins, 1979). Harkins (1987) has suggested that this reduction of effort stems from the fact that when participants in social loafing research "work together," their outputs are pooled; thus, they can receive neither credit nor blame for their performances. Consistent with this analysis, Karau and Williams (1993) report in a recently published metaanalysis, "In fact, social loafing was eliminated when evaluation potential was not varied across coactive (individual outputs identifiable [italics added]) and collective (individual outputs pooled [italics added]) conditions" (p. 696). Thus, the loafing paradigm provides a "no" or minimal evaluation baseline against which the effects of various sources of motivation can be measured, exactly as suggested by Bandura (1986). Given this minimal evaluation baseline, the impact of the potential for self-evaluation can be studied by manipulating a participant's access to the two pieces of information necessary for self-evaluation: (a) a measure of the participant's output and (b) an evaluative criterion against which this output can be compared. Szy@ manski and Harkins (1987) did exactly this in an experiment in whi...
