The impact of intrinsic and extrinsic features on delay discounting.

Delay discounting refers to the tendency of people to evaluate immediate rewards as being more valuable than those that are distant in time. Several models explain this phenomenon by a set of intrinsic and extrinsic features. Intrinsic features are related to the inherent traits and neurological conditions of the individual, whereas extrinsic features are related to the characteristics of the reward. In this study, we refer to extraversion and attention-deficit/hyperactivity disorder symptoms (attention and hyperactivity-impulsivity) as intrinsic features, and to fungibility, perishability, and magnitude of the reward as extrinsic features. Whereas there is a known main effect to these intrinsic and extrinsic features, the current research examines their additive and interactive contributions to delay discounting. A total of 222 participants filled out an online questionnaire measuring intrinsic features and presenting decision tasks with different types of rewards. The scores of the intrinsic variables and the delay discounting rate for each reward were calculated and analyzed. The results replicated previous findings showing main effects of hyperactivity, fungibility, perishability, and magnitude. They also provided new findings on an interaction between fungibility-perishability and hyperactivity-the effect of hyperactivity on delay discounting was larger when the rewards were fungible and nonperishable than when the rewards were perishable and nonfungible. This interaction has practical implications that can help in moderating delay discounting in clinical treatments of impulsivity as well as in constructing efficient economic models for consumers.