THE RELATIONSHIP BETWEEN THE ILLUSION OF CONTROL AND THE DESIRABILITY BIAS

Desirability bias is the tendency to overpredict desirable outcomes and underpredict unwanted results. The illusion of control is the tendency to believe that, or act as if, one can skillfully influence and control outcomes of chance events. These two related phenomena cause people to paint a 'rosy picture' of current reality or the future (McKenna, 1993). The circumstances under which the two biases operate and the nature of the relationship between them have been the subject of speculation in a few recent papers (Koehler et al., 1994; Friedland, 1992; McKenna, 1993). We report three experiments attempting to distinguish between the two biases and establish their generality. The first experiment demonstrates that, when predicting and judging unique events, the two response tendencies are influenced by different factors. The second and third experiments confirm that the tendency to overpredict desirable outcomes is uncorrelated with control, and that the illusion of control vanishes when multiple predictions are involved (Koehler ct al., 1994). We conclude that desirability bias and illusion of control are two distinct response biases. Only under very special circumstances are they affected by the same factors.