Research Article
Espen A. Sjoberg & Espen B. Johansen
Human Ethology Bulletin, Volume 33, No 2, 22-36, published June 30, 2018
DOI: https://doi.org/10.22330/heb/332/022-036
ABSTRACT
The delay discounting paradigm involves choosing between a small, immediate reward and a larger, delayed reward. As the delay between response and reinforcer increases for the large reward, people with Attention-Deficit/Hyperactivity Disorder (ADHD) tend to choose the small reward more often than controls. Studies on an animal model of ADHD, the Spontaneously Hypertensive Rat (SHR), find similar results. This pattern is typically interpreted as impulsive behaviour, implying that an unwillingness to wait decreases the likelihood of choosing the large reward. Alternatively, the results can be interpreted in terms of optimality, where a switch in preference from large to small rewards indicates sub-optimal behaviour. We critically discuss available evidence on delay discounting in ADHD and the SHR model, and evaluate whether an optimality perspective provides a useful interpretation of the data. Our findings suggest that optimality is a term that contributes little to explaining behaviour in delay discounting, outside of acting as a mathematical measure of reward maximization. Impulsive behaviour is best explained as a consequence of controlling variables, first and foremost the delay between response and reward, but also to a certain degree the inter-trial-interval and the reward magnitude.
Keywords: Impulsivity, Optimality Theory, Attention-Deficit/Hyperactivity Disorder, Spontaneously Hypertensive Rat, Inter-trial-interval.
.
ISSN: 2224-4476
