Delay discounting (DD) typically refers to the preference for smaller immediate rewards over larger but delayed rewards and to the well established fact that the subjective value of reward decreases with increasing delay to its receipt. In more general terms, when the consequences of one’s actions are delayed, they decrease in value and are less effective in controlling ongoing behavior (Reynolds 2006). Individuals with a high rate of DD tend to discount longer-term consequences of their decisions and actions, and their behavior is largely driven by the prospects of immediate gratification rather than the pursuit of longer term goals. Experimental procedures for measuring DD were originally developed in animal studies of operant behavior. In these procedures, animals chose between smaller immediate rewards such as one pellet of food and larger rewards such as two pellets of food delivered after a certain delay (Ainslie 1975; Monterosso and Ainslie 1999). In humans, different measures of DD involving hypothetical or real monetary rewards have been used as a model for impulsive choice, i.e. the tendency to select small immediate gains rather than larger but delayed rewards (reviewed in Reynolds 2006).
