The effect of adding a constant to all payoffs: experimental investigation, and implications for reinforcement learning models

This paper examines the effect on learning in simple decision tasks of the addition of a constant to all payoffs. Experiment 1 reveals that this effec t, initially observed in a probability learning task, is not limited to sin gle person decision making under uncertainty. Experiment 2 shows that the e ffect is not linear. Two additional experiments show that the non-linearity cannot be explained by whether zero is in the payoff range. The implicatio ns of these results for reinforcement learning models are evaluated and two models that capture the main results are proposed. (C) 1999 Elsevier Scien ce B.V, All rights reserved. JEL classification: C72; C92.