Justification of Effort by Humans and Pigeons

Abstract

Justification of effort by humans is a form of reducing cognitive dissonance by enhancing the value of rewards when they are more difficult to obtain. Presumably, assigning greater value to rewards provides justification for the greater effort needed to obtain them. We have found such effects in adult humans and children with a highly controlled laboratory task. More importantly, under various conditions we have found similar effects in pigeons, animals not typically thought to need to justify their behavior to themselves or others. To account for these results, I propose a simpler mechanism than justification of effort—a mechanism based on contrast between the end of the effort and the reinforcement (or signal for reinforcement) that follows. This model predicts that any relatively aversive event can serve to enhance the value of the reward that follows it simply through the contrast between those two events. In support of this general model, my colleagues and I have found this effect in pigeons when the prior event consists of (a) more rather than less effort (pecking), (b) a long rather than a short delay, and (c) the absence of food rather than food. We have also found that a pigeon’s preference for food at one location can shift toward a different location if acquiring food at the new location requires that the pigeon work harder to obtain the food. Contrast may also play a role in other social psychological phenomena that have been interpreted in terms of cognitive dissonance.