Delay Discounting Task
AKA: Delay and Probability Discounting Procedure
Background
Time delay (and/or probability) discounting procedures (DD) are research methods to establish a person's discount rate k as a behaviorally-based measure of impulsivity, with high k-values (= greater discounting) indicating more impulsive behavior. Specifically, DD procedures set out to find points at which individuals start devaluing (aka 'discounting') higher rewards (e.g. money) with longer wait periods in favor of smaller pay-offs with shorter wait periods or more certainty.
For example, if you were asked "Would you rather get $100 dollars in 1 week or get $10 right now?" would the higher pay-off with the longer wait period be more desirable to you than the lower pay-off you could get immediately? And if so, at what $ amount that you could take home right now would you change your mind?
DD procedures typically pin a standard reward (e.g. $100) with various time delays (e.g. 1 week) or win probabilities (e.g. 25%) against variable pay-offs that are paid immediately or with 100% certainty. These variable pay-offs get then systematically adjusted up or down to narrow down the amount at which a participant becomes indifferent to the higher reward and view the smaller immediate one as equally desirable. By establishing multiple such 'indifference' points for different delays, researchers can then use non-linear regression to fit these data points to hyperbolic functions to estimate the best-fit discount rate k for an individual's choices.
A classic DD procedure for establishing such delay and probability 'indifference' points for a monetary reward was introduced by Jerry Richards and colleagues in 1999. While some DD procedures systematically adjust the variable amounts by fixed increments, Richards et al developed an algorithm that randomly adjusted values within specific upper and lower boundaries that are constantly updated based on the participant's choices to narrow down indifference points for various time delays and probabilities. In addition, the DD procedure by Richards et al uses a randomized order of all time and probability delays in the same testing session to reduce order and anticipation effects. To increase the validity of the obtained indifference points and reduce random responding, real money is awarded at the end of a session that is based on one randomly selected choice of the participant.
Richards et al as well as subsequent research with DD tasks has provided strong evidence that DD tasks are reliable and valid measures of choice impulsivity.
Task Procedure
After learning about the basic choice task in the Richards DD Procedure with Random Adjustments, the participant is informed that at the end of the session, one of the choices they make will be selected at random and they will receive whatever they chose in response to that question. For selected time delays, the money would be left in an envelope that could be picked up at the specified delay. For selected probabilities, a token would be pulled from a bag containing two colors of tokens in the proportion that reflects the selected probability.
During each individual trial, the participant has to answer basic questions such as these "Would you rather have (a) $5 now or (b) $10 in 30 days?" (time delay) or "Would you rather have (a) $5 for sure or (b) $10 with a 90% chance?" (probability delay). If the participants wants the offered smaller but immediate amount, they press the provided 'A' button, if they prefer the higher amount of $10 despite the delay they press the provided 'B' button instead.
The time and probability delay questions are provided at random until the computer has established indifference points for all 5 time- and probability delays or after a total of 300 trials. Distractor trials are also run to further obfuscate the ongoing indifference point evaluations.
What it Measures
Delay Discounting (DD) procedures are behavioral assessment tool of impulsivity, specifically choice impulsivity
Psychological domains
- Inhibitory Control: The ability to withhold a "rash" response for immediate gain in favor of a more valuable future outcome.
Main Performance Metrics
- Indifference Points: Estimated indifference points for various delays
Psychiatric Conditions
Higher discount rates k are linked to the following conditions:
- Addictive Disorders
- Substance Abuse
- Gambling
- Attention Deficit Hyperactivity Disorder (ADHD)
- Bipolar Disorder
- Borderline Personality Disorder (BPD)
Test Variations
The Delay Discounting Task developed by Richards, Zhang, Mitchell, and De Wit (1999). The procedure uses a random adjustment algorithm to produce discount estimates (i.e., indifference points) for 10 different delays.
The Delay Discounting Task developed by Cherek, Moeller, Dougherty, and Rhoades (1997). The task provides a measure of impulsivity by evaluating discount rates for rewards delayed by 10 seconds.
An adaptation of the delay discounting task for adolescents used in the ABCD Consortium's longitudinal study on cognitive development from childhood to early adulthood.
An adaptation of the delay discounting task for adolescents used in the ABCD Consortium's longitudinal study on cognitive development from childhood to early adulthood.
An adaptation of the delay discounting task for adolescents used in the ABCD Consortium's longitudinal study on cognitive development from childhood to early adulthood.
Then Experiential Delay Discounting Task used by Reynolds & Schiffbauer (2004) to measure value assigned by a participant to experienced delays.
A brief, 5-question delay discounting task that takes under a minute to administer designed by Koffarnus, Warren, and Bickel (2014).
The Delay Discounting Task involving money and food. The task modeled off of the task used by Odum, Baumann, and Rimington (2006) and in developmenet by Leonard Epstein et al (2010).
References
Search Google Scholar for peer-reviewed, published research using the Inquisit Delay Discounting Task.
Cherek, D. R., Moeller, F. G, Dougherty, D. M., Rhoades, H. (1997). Studies of Violent and Nonviolent Male Parolees: II. Laboratory and Psychometric Measurements of Impulsivity. Biological Psychiatry, 41, 523-529.
Richards, J. B., Zhang, L., Mitchell, S. H., De Wit, H. (1999). Delay or probability discounting in a model of impulsive behavior: Effect of alcohol. Journal of the Experimental Analysis of Behavior, 71, 121-143.
Madden, G. J., Bickel, W. K., Jacobs, E. A. (1999). Discounting of Delayed Rewards in Opioid-Dependent Outpatients: Exponential or Hyperbolic Discounting Functions? Experimental and Clinical Psychopharmacology, 7, 284-293.
Moeller, F. G., Dougherty, D. M, Barratt, E. S., Oderinde, V, Mathias, C. W., Harper, R. A., Swann, A. C. (2002). Increased impulsivity in cocaine dependent subjects independent of antisocial personality disorder and aggression, Drug and Alcohol Dependence, 68, 105-111.
Reynolds, B. & Schiffbauer, R. (2004). Measuring state changes in human delay discounting: an experiential discounting task. Behavioural Processes, 67, 343–356.
Odum, A.L., Baumann, A.A.L., Rimington, D.D. (2006). Discounting of delayed hypothetical money and food: Effects of amount. Behavioural Processes, 73, 278-284.
Odum, A.L., Baumann, A.A.L., Rimington, D.D. (2006). Discounting of delayed hypothetical money and food: Effects of amount. Behavioural Processes, 73, 278-284.
Robles, E., Vargas, P. A., Bejarano, R. (2009). Within-subject differences in degree of delay discounting as a function of order of presentation of hypothetical cash rewards. Behavioral Processes, 81, 260-263.
Epstein, L. H., Salvy, S. J., Carr, K. A., Dearing, K. K., & Bickel, W. K. (July 01, 2010). Food reinforcement, delay discounting and obesity. Physiology & Behavior, 100, 5, 438-445.
Smits,R.R, Stein,J.S., Johnson, P.S., Odum, A.L., & Madden, G.J. (2013). Test–Retest Reliability and Construct Validity of the Experiential Discounting Task. Experimental and Clinical Psychopharmacology, 21, 155–163.
Koffarnus, M.N. & and Warren K. Bickel, W.K (2014). A 5-Trial Adjusting Delay Discounting Task: Accurate Discount Rates in Less Than One Minute. Experimental and Clinical Psychopharmacology, 22, 222–228.
Tucker, J., Cheong, J., Chandler, S., Lambert, B., Kwok, H., & Pietrzak, B. (2016). Behavioral economic indicators of drinking problem severity and initial outcomes among problem drinkers attempting natural recovery: A cross‐sectional naturalistic study. Addiction, 111(11), 1956-1965.
Friedel, J., DeHart, W., Frye, C., Rung, J., Odum, A., & Evans, Suzette M. (2016). Discounting of Qualitatively Different Delayed Health Outcomes in Current and Never Smokers. Experimental and Clinical Psychopharmacology, 24(1), 18-29.
Stein, J., Sze, S., Athamneh, Y., Koffarnus, L., Epstein, M., & Bickel, N. (2017). Think fast: Rapid assessment of the effects of episodic future thinking on delay discounting in overweight/obese participants. Journal of Behavioral Medicine, 40(5), 832-838.
Luciana, M, Bjork, J.M, Nagel, B.J, Barch, D.M, Gonzalez, R, Nixon, S.J, & Banich, M.T. (2018). Adolescent neurocognitive development and impacts of substance use: Overview of the adolescent brain cognitive development (ABCD) baseline neurocognition battery. Developmental Cognitive Neuroscience, 32, 67-79.