Studying the relation between temporal reward discounting tasks used in populations with ADHD: A factor analysis

Background: This study aimed at investigating the relationship between tasks that have been used in attention deficit hyperactivity disorder (ADHD) to measure choices between smaller immediate and larger delayed rewards: real and hypothetical temporal discounting tasks, and single-choice paradigms. Methods: Participants were 55 undergraduate psychology students. Tasks included a real and hypothetical version of a temporal discounting (TD) task with choices between a large reward (10 cents) after delays up to 60 seconds, and smaller immediate rewards (2-8 cents); two versions of a hypothetical temporal discounting task with choices between a large reward ($100) after delays up to 120 months, and smaller immediate rewards ($1-$95); a Choice Delay Task with choices between one point now and two points after 30 seconds (one point is worth five cents). Results: Correlation analyses showed that the real and the hypothetical TD tasks with 10 cents were very strongly associated. However, the hypothetical TD tasks with $100 did not correlate with either the real or the hypothetical TD task with 10 cents. Principal component analysis extracted two components: one for small amounts and short delays, and a second one for large rewards and long delays. Conclusions: Temporal reward discounting is not a uniform construct. Functional brain imaging research could shed more light on unique brain activation patterns associated with different forms of temporal reward discounting. Copyright (C) 2010 John Wiley & Sons, Ltd.