The effect of sufficiency and necessity on perceptions of control and responsibility

Discrepancies in perceptions of control and responsibility have been depicted as paradoxical because both types of perceptions are presumed to reflect perceptions of causality. The paradox may, in part, reflect a failure to distinguish between two dimensions of an actor's causality: sufficiency and necessity. Sufficiency of an actor is defined as the ability of the actor to bring about or prevent an outcome. Necessity of an actor is defined as the inverse of the sufficiency of other actors. In the studies described here, the sufficiency and necessity of an actor is varied, and subjects are asked to rate the actor's control and responsibility. The findings from Studies 1 and 2 support the prediction that variations in sufficiency have a greater effect on perceptions of control than on perceptions of responsibility; the findings from Study 2 support the prediction that variations in necessity have a greater effect on perceptions of responsibility than on perceptions of control. Studies 3 and 4 further demonstrate the occurrence of the paradox, and support the general conclusion that the effect of sufficiency relative to the effect of necessity is greater for perceptions of control than for perceptions of responsibility. The tendency of sufficiency to have a greater effect on males than on females, and the tendency of necessity to have a greater effect on females than on males, are linked to findings from previous research.