Effects of Opportunity Costs on Delay Discounting for Hypothetical Food and Money

Abstract

Delay discounting refers to a decrease in subjective value of an outcome as its receipt is delayed. In discounting studies, properties of the delay are important, but understudied, methodological details. One aspect of the delay is opportunity costs, which refers to alternative reinforcement that is forgone while waiting for a reward. Research shows that verbal narratives specifying high opportunity costs lead to steeper discounting for money and cigarettes. However, opportunity costs have not been examined with food discounting. The current study examined the extent to which opportunity costs affect discounting for money (Experiment 1) and food (Experiment 2) using within-subjects designs. Participants were presented with narratives specifying differing magnitudes of opportunity costs prior to completing four discounting tasks for two magnitudes of money (Exp 1) or food (Exp 2). Results indicated that as opportunity costs increased, discounting for both money and food also increased. Magnitude effects were also found; the smallest magnitudes of money and food were discounted most steeply. Lastly, systematic responding was lower, but more consistent across opportunity costs for food compared to money, indicating choice stability with money is more sensitive to opportunity costs. These results then replicate and extend opportunity costs to food discounting.