Blanco, F. , Matute, H. & Vadillo, M. A.
Departamento de Fundamentos y Métodos de la Psicología. University of Deusto. Bilbao, Spain.
The probability of responding, P(R), is known to bias contingency judgments between actions and uncontrollable outcomes. That is, the more active a participant is, the more likely he/she is to overestimate the null contingency, and thus to develop an illusion of control. The current two experiments test a potential account for this P(R) bias: by responding with high P(R), participants may accidentally expose themselves to higher values of actual contingency. Contrary to this account, our results indicate that contingency overestimations are better predicted by P(R) itself than by any differential exposure to contingency. Moreover, as training proceeds, the actual contingency participants are exposed to gets closer to the programmed zero contingency value. However, this does not result in more accurate judgments of control. This finding motivates a discussion on a potential volitional component of the P(R) bias.