Name: measuring delay discounting in humans using an adjusting amount task
Uploaded: 2016-01-09T14:00:01
Description: Watch this Scientific Journal Video about Measuring Delay Discounting in Humans Using an Adjusting Amount Task at JoVE.com

Preparation of this manuscript was supported in part by grant R01DA029100 from the National Institute on Drug Abuse.

The protocol was approved by the Institutional Review Board at Utah State University. The steps outlined below should serve as a guide for programming and conducting a delay discounting task.
1. Setting up a Delay Discounting Task
<ol>
	<li>Choose the range of delays for which discounting will be assessed. 
	NOTE: For example, a typical scenario would use delays that range from 1 week to 25 years. The selected delays should follow, by convention, an approximately exponential progression...

<ol>
	<li>Friedel, J. E., DeHart, W. B., Madden, G. J., Odum, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsivity+and+cigarette+smoking:+discounting+of+monetary+and+consumable+outcomes+in+current+and+non-smokers.">Impulsivity and cigarette smoking: discounting of monetary and consumable outcomes in current and non-smokers.</a> Psychopharmacology. 231 (23), 4517-4526 (2014).</li><li>Bickel, W. K., Odum, A. L., Madden, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsivity+and+cigarette+smoking:+delay+discounting+in+current,+never,+and+ex-smokers.">Impulsivity and cigarette smoking: delay discounting in current, never, and ex-smokers.</a> Psychopharmacology. 146 (4), 447-454 (1999).</li><li>Rachlin, H., Raineri, A., Cross, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subjective+probability+and+delay.">Subjective probability and delay.</a> J Exp Anal Behav. 55 (2), 233-244 (1991).</li><li>Addessi, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+choice+versus+delay+maintenance:+Different+measures+of+delayed+gratification+in+capuchin+monkeys+(Cebus+apella).">Delay choice versus delay maintenance: Different measures of delayed gratification in capuchin monkeys (Cebus apella).</a> J Comp Psychol. 127 (4), 392-398 (2013).</li><li>Woolverton, W. L., Myerson, J., Green, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting+of+cocaine+by+rhesus+monkeys.">Delay discounting of cocaine by rhesus monkeys.</a> Exp Clin Psychopharm. 15 (3), 238-244 (2007).</li><li>Evenden, J. L., Ryan, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pharmacology+of+impulsive+behaviour+in+rats:+the+effects+of+drugs+on+response+choice+with+varying+delays+of+reinforcement.">The pharmacology of impulsive behaviour in rats: the effects of drugs on response choice with varying delays of reinforcement.</a> Psychopharm. 128 (2), 161-170 (1996).</li><li>Perry, J. L., Larson, E. B., German, J. P., Madden, G. J., Carroll, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsivity+(delay+discounting)+as+a+predictor+of+acquisition+of+IV+cocaine+self-administration+in+female+rats.">Impulsivity (delay discounting) as a predictor of acquisition of IV cocaine self-administration in female rats.</a> Psychopharmacology. 178 (2-3), 193-201 (2005).</li><li>Mazur, J. E., Commons, M. L., Mazur, J., Nevin, J. A., Rachlin, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+adjusting+procedure+for+studying+delayed+reinforcement.+In:+.">An adjusting procedure for studying delayed reinforcement. In: .</a> Quantitative Analysis of Behavior: Vol. 5 the Effect of Delay and Intervening Events on Reinforcement Value. , 55-73 (1987).</li><li>Bickel, W. K., Jarmolowicz, D. P., Mueller, E. T., Koffarnus, M. N., Gatchalian, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Excessive+discounting+of+delayed+reinforcers+as+a+trans-disease+process+contributing+to+addiction+and+other+disease-related+vulnerabilities:+Emerging+evidence.">Excessive discounting of delayed reinforcers as a trans-disease process contributing to addiction and other disease-related vulnerabilities: Emerging evidence.</a> Pharmacol Thera. 134 (3), 287-297 (2012).</li><li>Rachlin, H., Green, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commitment,+choice,+and+self-control.">Commitment, choice, and self-control.</a> J Exp Anal Behav. 17 (1), 15-22 (1972).</li><li>Ainslie, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulse+control+in+pigeons.">Impulse control in pigeons.</a> J Exp Anal Behav. 21 (3), 485-489 (1974).</li><li>Ainslie, G., Herrnstein, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preference+reversal+and+delayed+reinforcement.">Preference reversal and delayed reinforcement.</a> Anim Learn Behav. 9 (4), 476-482 (1981).</li><li>Odum, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting:+I'm+a+k,+you're+a+k.">Delay discounting: I'm a k, you're a k.</a> J Exp Anal Behav. 96 (3), 427-439 (2011).</li><li>Reynolds, B., Ortengren, A., Richards, J. B., de Wit, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dimensions+of+impulsive+behavior:+Personality+and+behavioral+measures.">Dimensions of impulsive behavior: Personality and behavioral measures.</a> Pers Indiv Differ. 40 (2), 305-315 (2006).</li><li>Petry, N. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting+of+money+and+alcohol+in+actively+using+alcoholics,+currently+abstinent+alcoholics,+and+controls.">Delay discounting of money and alcohol in actively using alcoholics, currently abstinent alcoholics, and controls.</a> Psychopharmacology. 154 (3), 243-250 (2001).</li><li>Vuchinich, R. E., Simpson, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperbolic+temporal+discounting+in+social+drinkers+and+problem+drinkers.">Hyperbolic temporal discounting in social drinkers and problem drinkers.</a> Exp Clin Psychopharm. 6 (3), 292-305 (1998).</li><li>Bickel, W. K., Odum, A. L., Madden, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsivity+and+cigarette+smoking:+delay+discounting+in+current,+never,+and+ex-smokers.">Impulsivity and cigarette smoking: delay discounting in current, never, and ex-smokers.</a> Psychopharmacology. 146 (4), 447-454 (1999).</li><li>Mitchell, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measures+of+impulsivity+in+cigarette+smokers+and+non-smokers.">Measures of impulsivity in cigarette smokers and non-smokers.</a> Psychopharmacology. 146 (4), 455-464 (1999).</li><li>Coffey, S. F., Gudleski, G. D., Saladin, M. E., Brady, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsivity+and+rapid+discounting+of+delayed+hypothetical+rewards+in+cocaine-dependent+individuals.">Impulsivity and rapid discounting of delayed hypothetical rewards in cocaine-dependent individuals.</a> Exp Clin Psychopharm. 11 (1), 18-25 (2003).</li><li>Madden, G. J., Petry, N. M., Badger, G. J., Bickel, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impulsive+and+self-control+choices+in+opioid-dependent+patients+and+non-drug-using+control+patients:+Drug+and+monetary+rewards.">Impulsive and self-control choices in opioid-dependent patients and non-drug-using control patients: Drug and monetary rewards.</a> Exp Clin Psychopharm. 5 (3), 256-262 (1997).</li><li>Odum, A. L., Madden, G. J., Badger, G. J., Bickel, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Needle+sharing+in+opioid-dependent+outpatients:+psychological+processes+underlying+risk.">Needle sharing in opioid-dependent outpatients: psychological processes underlying risk.</a> Drug Alcohol Depen. 60 (3), 259-266 (2000).</li><li>Hoffman, W. F., Moore, M., Templin, R., McFarland, B., Hitzemann, R. J., Mitchell, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropsychological+function+and+delay+discounting+in+methamphetamine-dependent+individuals.">Neuropsychological function and delay discounting in methamphetamine-dependent individuals.</a> Psychopharmacology. 188 (2), 162-170 (2006).</li><li>Dixon, M. R., Marley, J., Jacobs, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting+by+pathological+gamblers.">Delay discounting by pathological gamblers.</a> J Appl Behav Anal. 36 (4), 449-458 (2003).</li><li>Weller, R. E., Cook, E. W., Avsar, K. B., Cox, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obese+women+show+greater+delay+discounting+than+healthy-weight+women.">Obese women show greater delay discounting than healthy-weight women.</a> Appetite. 51 (3), 563-569 (2008).</li><li>Rasmussen, E. B., Lawyer, S. R., Reilly, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Percent+body+fat+is+related+to+delay+and+probability+discounting+for+food+in+humans.">Percent body fat is related to delay and probability discounting for food in humans.</a> Behav Process. 83 (1), 23-30 (2010).</li><li>Daugherty, J. R., Brase, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Taking+time+to+be+healthy:+Predicting+health+behaviors+with+delay+discounting+and+time+perspective.">Taking time to be healthy: Predicting health behaviors with delay discounting and time perspective.</a> Pers Indiv Differ. 48 (2), 202-207 (2010).</li><li>Reynolds, B., Schiffbauer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+state+changes+in+human+delay+discounting:+an+experiential+discounting+task.">Measuring state changes in human delay discounting: an experiential discounting task.</a> Behav Process. 67 (3), 343-356 (2004).</li><li>Jimura, K., Myerson, J., Hilgard, J., Braver, T. S., Green, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+people+really+more+patient+than+other+animals?+Evidence+from+human+discounting+of+real+liquid+rewards.">Are people really more patient than other animals? Evidence from human discounting of real liquid rewards.</a> Psychon B. Rev. 16 (6), 1071-1075 (2009).</li><li>Odum, A. L., Rainaud, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discounting+of+delayed+hypothetical+money,+alcohol,+and+food.">Discounting of delayed hypothetical money, alcohol, and food.</a> Behav Process. 64 (3), 305-313 (2003).</li><li>Madden, G. J., Begotka, A. M., Raiff, B. R., Kastern, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting+of+real+and+hypothetical+rewards.">Delay discounting of real and hypothetical rewards.</a> Exp Clin Psychopharm. 11 (2), 139-145 (2003).</li><li>Beck, R. C., Triplett, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Test-retest+reliability+of+a+group-administered+paper-pencil+measure+of+delay+discounting.">Test-retest reliability of a group-administered paper-pencil measure of delay discounting.</a> Exp Clin Psychopharm. 17 (5), 345-355 (2009).</li><li>Chapman, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+discounting+and+utility+for+health+and+money.">Temporal discounting and utility for health and money.</a> J EXP Psychol Learn. 22 (3), 771-791 (1996).</li><li>Du, W., Green, L., Myerson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-cultural+comparisons+of+discounting+delayed+and+probabilistic+rewards.">Cross-cultural comparisons of discounting delayed and probabilistic rewards.</a> Psychol Rec. 52 (4), 479-492 (2002).</li><li>Kirby, K. N., Petry, N. M., Bickel, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heroin+addicts+have+higher+discount+rates+for+delayed+rewards+than+non-drug-using+controls.">Heroin addicts have higher discount rates for delayed rewards than non-drug-using controls.</a> J Exp.Psychol Gen. 128 (1), 78-87 (1999).</li><li>Myerson, J., Green, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discounting+of+delayed+rewards:+Models+of+individual+choice.">Discounting of delayed rewards: Models of individual choice.</a> J Exp Anal Behav. 64 (3), 263-276 (1995).</li><li>Rachlin, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Notes+on+discounting.">Notes on discounting.</a> J Exp Anal Behav. 85 (3), 425-435 (2006).</li><li>Odum, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+discounting:+Trait+variable.">Delay discounting: Trait variable.</a> Behav Process. 87 (1), 1-9 (2011).</li><li>Koffarnus, M. N., Jarmolowicz, D. P., Mueller, E. T., Bickel, W. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changing+delay+discounting+in+the+light+of+the+competing+neurobehavioral+decision+systems+theory:+a+review.">Changing delay discounting in the light of the competing neurobehavioral decision systems theory: a review.</a> J Exp Anal Behav. 99 (1), 32-57 (2013).</li><li>Green, L., Myerson, J., Ostaszewski, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amount+of+reward+has+opposite+effects+on+the+discounting+of+delayed+and+probabilistic+outcomes.">Amount of reward has opposite effects on the discounting of delayed and probabilistic outcomes.</a> J Exp Psychol Learn Mem Cogn. 25 (2), 418-427 (1999).</li><li>Myerson, J., Green, L., Warusawitharana, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Area+under+the+curve+as+a+measure+of+discounting.">Area under the curve as a measure of discounting.</a> J Exp Anal Behav. 76 (2), 235-243 (2001).</li><li>Reynolds, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+delay-discounting+research+with+humans:+relations+to+drug+use+and+gambling.">A review of delay-discounting research with humans: relations to drug use and gambling.</a> Behav Pharmacol. 17 (8), 651-667 (2006).</li><li>Anokhin, A. P., Golosheykin, S., Grant, J. D., Heath, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heritability+of+delay+discounting+in+adolescence:+A+longitudinal+twin+study.">Heritability of delay discounting in adolescence: A longitudinal twin study.</a> Behav Gen. 41 (2), 175-183 (2011).</li><li>Morrison, K. L., Madden, G. J., Odum, A. L., Friedel, J. E., Twohig, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altering+impulsive+decision+making+with+an+acceptance-based+procedure.">Altering impulsive decision making with an acceptance-based procedure.</a> Behav Ther. 45 (5), 630-639 (2014).</li></ol>

This video describes the steps that should be taken to conduct a delay discounting experiment using the adjusting amount task. The adjusting amount task is relatively quick to conduct (10 - 15 min per participant) and produces reliable data. The adjusting nature of the task provides a fine-tuned analysis of an individual participant&#39;s degree of discounting. Since the task is computer-based data collection is automated, which limits human-error and influence during the data collection process. Typically the task is us...

Delay discounting is a behavioral phenomenon that affects many situations people encounter Delay discounting refers to the fact that temporally proximal rewards are more highly valued than temporally distal rewards. That is, the value of rewards decline with delays. This is an important process because many choices that people make involve a tradeoff between immediate low quality outcomes (e.g., a piece of cheesecake after dinner) and delayed high quality outcomes (e.g., long-term health). Delay discounting has also been observed in a variety of species in addition to humans2,3, including monkeys4,5, rats6,7, and pigeons8.
Individual differences in degree of discounting have been linked to various maladaptive behaviors9. The value of rewards declines as a function of delay according to a hyperbolic decay function8. With hyperbolic decay, value decreases extensively with relatively short delays, but decreases proportionally less so across relatively long delays. Mazur&#39;s finding that value degrades hyperbolically as a function of delay is important, because the hyperbolic function is able to predict preference reversals where other theoretical functions cannot without additional assumptions. Preference reversals are a well-documented finding10-12 that preference for a small reward available relatively soon (SSR) over a larger reward available at a relatively distal point in the future (LLR) will reverse if a common delay is added to both alternatives. For example, if, while driving home from work, a feeling of hunger suddenly hits, a person may be inclined to stop at the first fast food restaurant in sight for a relatively unhealthy snack as opposed to waiting until they get home for a piece of fruit or some other high quality snack. If, however, the hunger hits while still at work, when the person still has to walk to their car and drive down the road before approaching the fast food restaurant, they are more likely to decide to wait until they get home for the fruit.
The steepness with which rewards decline in value as a function of delay can be considered a measure of an organism&#39;s choice impulsivity. Choice impulsivity can be defined as a preference for SSR over LLR13,14.Higher degrees of impulsive choice are linked to use and abuse of various drugs such as alcohol15,16, cigarettes17,18, cocaine19, heroin20,21, and methamphetamine22. Higher degrees of impulsive choice are also linked to problematic gambling23, obesity24,25, and poor health and personal safety choices26.
Various tasks can be used to assess delay discounting in humans. For instance, participants could be asked to make decisions between alternatives and experience some or all of the consequences associated with their choice (real reward task27,28) or they could be asked to make decisions between hypothetical alternatives, in which case they would not actually experience the consequences associated with their choice (hypothetical reward task1-3,9,15-19,25,29). Similar degrees of discounting are generally observed regardless of whether the reward and delays are real or hypothetical30. The method of administering delay-discounting tasks differs across studies. For example, various laboratories have administered the task using a fill-in-the-blank questionnaire31, a multiple-choice questionnaire32, an adjusting amount procedure33, and a monetary choice questionnaire34. The adjusting amount task, originally developed by Du, Green, and Myerson33, and used extensively in our laboratory, provides several benefits. Once the task is programmed data collection is automated, limiting human error throughout the process. Due to the adjusting nature of the task, indifference points are reached with relatively few questions, which minimizes the time participants are required to be in the and laboratory and limits boredom. Importantly, the task provides detailed and reliable data. The adjusting amount task will be detailed below.

<table border="0" cellpadding="0" cellspacing="0" width="613">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:165px;">Computer</td>
			<td style="width:124px;">any</td>
			<td style="width:116px;"></td>
			<td style="width:208px;">Mac or Windows</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Programming Software</td>
			<td>Visual Studios</td>
			<td></td>
			<td>https://www.visualstudio.com</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Data Analysis Software</td>
			<td>The R Foundation</td>
			<td></td>
			<td>http://www.r-project.org</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;">Informed Consent Form</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring delay discounting in humans using an adjusting amount task

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. Delay discounting tasks are used to identify indifference points, which reflect equal preference for two dichotomous reward alternatives differing in both delay and magnitude. Indifference points are key to assessing the shape of a delay-discounting gradient because they allow us to isolate the effect of delay on value. For example, if at a 1 week delay and a maximum of $1,000, the indifference point is at $700 we know that, for that participant, a 1-week delay corresponds to a 30% reduction in value. This video outlines an adjusting amount delay-discounting task that identifies indifference points relatively quickly and is inexpensive and easy to administer. Once data have been collected, non-linear regression techniques are typically used to generate discounting curves. The steepness of the discounting curve reflects the degree of impulsive choice of a group or individual. These techniques have been used with a wide range of commodities and have identified populations that are relatively impulsive. For example, people with substance abuse problems discount delayed rewards more steeply than control participants. Although degree of discounting varies as a function of the commodity examined, discounting of one commodity correlates with discounting of other commodities, which suggests that discounting may be a persistent pattern of behavior1.

Delay discounting results are commonly analyzed by fitting curvilinear regression models to both the median indifference points from the groups and indifference points from individual participants for each outcome. Median group indifference points are used because the indifference points for a sample are usually not normally distributed. Three non-linear regression models are commonly used: those suggested by Mazur (Equation 1)8, Myerson and Green (Equation 2)35, and...

Watch this Scientific Journal Video about Measuring Delay Discounting in Humans Using an Adjusting Amount Task at JoVE.com

Measuring Delay Discounting in Humans Using an Adjusting Amount Task

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. We outline a computer-based delay discounting task that is easy to implement and allows for the quantification of the degree of delay discounting in human participants.

Delay discounting refers to a decline in the value of a reward when it is delayed relative to when it is immediately available. Delay discounting tasks ...

The overall goal of this procedure is to provide a quantitative assessment of the effect of delay on the present value of a given commodity. This method, originally developed by Du, Green, and Myerson, allows for quantification of delayed discounting. Delayed discounting describes the degree to which delay impacts the present value of an outcome, and has been linked to a variety of risky behaviors, such as substance abuse, obesity, and gambling.The main advantage of this technique is that it provides a robust and reliable measure of delay discounting, in a relatively brief amount of time. While this method has often been used to describe preexisting differences across populations, our hope is that more work can build on its use as a diagnostic tool or target for intervention. Generally, experimentors new to this procedure may be challenged, because the procedure requires an algorithm for determining an indifference point, which must be embedded within a computer program.Visual demonstration of this method can be helpful, because small errors in the algorithm can lead to drastically different results. Begin by choosing the range of delays for which delay discounting will be assessed. Then, choose the maximum amount of money which will service the delayed outcome in the task.Following that, choose the number of trials that must be completed to determine an indifference point at each delay. Next, have the participant sit in an isolated room, in front of a computer. Ask them to turn off their cell phone or any other electronic devices.Provide the participant with an informed consent form to review and sign if they agree to participate in the task. Then, start the program by clicking the icon associated with the task on the computer. Observe the dialogue box, and enter a unique participant ID tag that will be attached to the participant's data.Give the participant instructions about what they will experience in the task. Next, provide practice trials that will not be included in data analysis to familiarize them with the task design. Begin the practice trials by showing a question on the computer, and asking the participant to choose between 10 available immediately and 100 available in one day.Observe the choice made on the screen. Ask the same question on the next screen, but for subsequent choices, increase the immediate alternative by an increment of 10 on each trial, regardless of the choices made by the participant, until the immediate and delayed alternatives are equal to 100. Finally, have the participant complete 10 practice trials to allow them to acclimate to the task.To assess the indifference point, first display the starting amounts for the delayed and immediate alternatives to participants. For the first trial, display the maximum amount as the delayed alternative, and simultaneously display the immediate amount as half of the maximum amount. Set the mouse cursor to the center of the screen at the beginning of each trial, and then observe the participant's choice.Adjust the amount of the immediate alternative by one fourth of the maximum for the second trial, based on the participant's choice. For example, if the participant chose the immediate option, decrease the amount of the immediate choice by 25 for the second trial. If the participant chose the delayed option, increase the amount of the immediate choice by 25 for the second trial.Then, display the new amount of the immediate choice and a constant delayed choice to the participant, and allow them to complete the second trial. Observe their choice. Then, adjust the amount of the immediate alternative by half of the previous adjustment.For example, if the participant chose the immediate option, decrease the amount of the immediate choice for the third trial by 12.50. If the participant chose the delayed option, increase the amount of the immediate choice for the third trial by 12.50. Repeat the adjustments to the immediate amount until the participant has made the required number of choices, which is at the discretion of the experimenter.Make the final adjustment to the immediate amount based on the participant's choice, and use this new amount as the indifference point for that particular delay. Fully repeat the entire adjustment process for each of the chosen delays, by resetting the amount of the immediate outcome, and the amount of the adjustment for the first trial at each delay. To assess delay discounting of qualitatively different outcomes, ask the participant to provide an example of the chosen outcome.For example, if the chosen outcome is food, then ask the participant to supply their favorite food. Record the participant's response, and ask the participant how much a unit of the outcome costs. Next, display the amount of the immediate and delayed starting amounts, based on the price reported by the participant.Set the delayed amount of the outcome to be equal to the maximum amount divided by the per-unit price that was provided by the participant, and set the immediate alternative to 0.5 of that amount. Finally, repeat the adjustment process to determine the indifference point for each outcome. This protocol outlines how to conduct a delay discounting experiment, using the adjusting amount task and human participants across various outcomes.Here, discounting functions are shown for smokers and non-smokers, across the commodities of money, alcohol, entertainment, and food. The median indifference points indicate that food is discounted more steeply than money. Once correctly programmed, this technique only takes approximately 10 minutes to assess the degree of delay discounting for a single commodity.While attempting this procedure, it's important to remember to stress to participants that there are no correct answers, and that each participant should choose their most preferred alternative. This technique has been used by a variety of laboratory groups to assess delay discounting and link it to a variety of risky behaviors. After watching this video, you should have a good understanding of how to set up and program delay discounting tasks.In the supplemental materials, we provide a code that can be used to program a delay discounting task. We also provide non-linear regression models that can be fit to the data. These models allow for quantification of the degree of delay discounting.

Research

JoVE Journal

Behavior

The Crossmodal Congruency Task as a Means to Obtain an Objective Behavioral Measure in the Rubber Hand Illusion Paradigm

The rubber hand illusion (RHI) is a popular experimental paradigm. Participants view touch on an artificial rubber hand while the participants' own hidden ...

Studying Food Reward and Motivation in Humans

A key challenge in studying reward processing in humans is to go beyond subjective self-report measures and quantify different aspects of reward such as ...

Measurement of Fronto-limbic Activity Using an Emotional Oddball Task in Children with Familial High Risk for Schizophrenia

Adolescence is a critical developmental period where the early symptoms of schizophrenia frequently emerge. First-degree relatives of people with ...

An Operant Intra-/Extra-dimensional Set-shift Task for Mice

Alterations in executive control and cognitive flexibility, such as attentional set-shifting abilities, are core features of several neuropsychiatric ...

Determining Pain Detection and Tolerance Thresholds Using an Integrated, Multi-Modal Pain Task Battery

Human pain models are useful in the assessing the analgesic effect of drugs, providing information about a drug&#39;s pharmacology and identify ...

An Automated T-maze Based Apparatus and Protocol for Analyzing Delay- and Effort-based Decision Making in  Free Moving Rodents

Many neurological and psychiatric patients demonstrate difficulties and/or deficits in decision making. Rodent models are helpful to produce a deeper ...

Classical Short-Delay Eyeblink Conditioning in One-Year-Old Children

Classical eyeblink conditioning (EBC) refers to the learned association between a conditioned stimulus (an auditory tone) and an unconditioned stimulus (a ...

Using Facial Electromyography to Assess Facial Muscle Reactions to Experienced and Observed Affective Touch in Humans

"Affective" touch is believed to be processed in a manner distinct from discriminatory touch and to involve activation of C-tactile (CT) afferent fibers. ...

Examining Bilingual Language Control Using the Stroop Task

The Stroop task in its many variations has been used in fields such as psychology, linguistics, and neuroscience to examine questions regarding the ...

Measuring Light-Switching Behavior Using an Occupancy and Light Data Logger

Due to discrepancies between self-reported and observed pro-environmental behavior, researchers suggest the use of more direct measures of behavior. ...