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 (e.g., 1 week, 2 weeks, 1 month, 2 months, 6 months, 1 year, 5 years, and 25 years)</li>
	<li>Choose the maximum amount of money that will be used in the task. For example, typical amounts of money used in the task are $100 or $1,000.</li>
	<li>Choose the number of trials that must be completed to determine an indifference point at each delay. 
	NOTE: For example, a typical number of trials for each delay should be between 6 to 8 trials to balance data resolution and participant fatigue.</li>
</ol>
2. Obtain Informed Consent and Login Participant
<ol>
	<li>Have the participant sit in an isolated room in front of a computer. Ask the participant to turn off their cell phone and/or any other electronic devices.</li>
	<li>Provide the participant with an informed consent form to review and sign if they agree to participate in the task.</li>
	<li>Start the program by clicking the icon associated with the task on the computer.</li>
	<li>Observe the dialogue box and enter a unique participant ID tag that will be attached to the participant&#39;s data. 
	NOTE: Because the task must be programmed by experimenters, this step could be automated by having the program assign a participant tag automatically.</li>
</ol>
3. Provide Instructions and Practice Trials
<ol>
	<li>Give the participant instructions about what he or she will experience in the task.</li>
	<li>Provide practice trials that will not be included in data analysis. 
	NOTE: The practice trials are designed to familiarize participants with the task design and provide participants the opportunity to ask questions if they fail to understand what is expected of them without threatening the integrity of the data collected at the beginning of the task. Practice trials should not use the adjusting procedure outlined below. Instead, practice trials should simply consist of a series of choices between immediate outcomes and delayed outcomes.
	<ol>
		<li>For example, begin the practice trials by showing a question on the computer screen and asking the participant to choose between $10 available immediately and $100 available in 1 month. Observe the choice made on the screen.</li>
		<li>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.</li>
	</ol>
	</li>
	<li>Carry out ten practice trials to allow the participant to acclimate to the task.</li>
</ol>
4. Assess a Single Indifference Point
NOTE: Indifference points serve as the major dependent variable from delay discounting tasks and represent a point at which the present value of the delayed alternative is equal to that of the immediate alternative.
<ol>
	<li>Display the starting amounts for the delayed and immediate alternatives to participants. For the first trial, display the maximum amount as the amount for the delayed alternative. Simultaneously display the immediate amount as &#189; of the maximum amount. Set the mouse cursor to the center of the screen (equidistant from each of the choice alternatives) at the beginning of the trial. 
	NOTE: The side (right or left side of the screen) on which an alternative is presented should be randomly determined on each trial.</li>
	<li>Observe the participant&#39;s choice.</li>
	<li>Adjust the amount of the immediate alternative by &#188; of the maximum for the second trial based on the participants choice.
	<ol>
		<li>Decrease the amount of the immediate alternative for the second trial if the participant chose the immediate alternative on the first trial. For example, if the immediate amount was $50 and it was chosen on the first trial, then on the second trial display the immediate amount as $25.</li>
		<li>Increase the amount of the immediate alternative for the second trial if the participant chose the delayed alternative on the first trial. For example, if the immediate amount was $50, but the delayed amount was chosen on the first trial, then on the second trial display the immediate amount as $75.</li>
	</ol>
	</li>
	<li>Display the new amount of the immediate alternative and the constant delayed alternative to the participant and allow them to make their next choice.</li>
	<li>Observe the participant&#39;s choice and adjust the amount of the immediate alternative by &#189; of the previous adjustment.
	<ol>
		<li>Decrease the amount of the immediate alternative for the next trial if the participant chose the immediate alternative on the current trial. For example, if the immediate amount was $25 on the second trial and it was chosen, then on the third trial display the immediate amount as $12.50.</li>
		<li>Increase the amount of the immediate alternative for the next trial if the participant chose the delayed alternative on the current trial. For example, if the immediate amount was $25 on the second trial and it was chosen, then on the third trial display the immediate amount as $37.50.</li>
	</ol>
	</li>
	<li>Repeat steps 4.4 and 4.5 until the participant has made the required number of choices 
	NOTE: The number of choices is up to the discretion of the experimenter; see discussion for further detail. 
	NOTE: The adjustment for the upcoming trial should always be equal to the maximum amount multiplied by 2-n, where n is the trial number for the current adjustment (see Figure 1).</li>
	<li>Make the final adjustment to the immediate amount based on the participant&#39;s choice. Use this new amount as the indifference point for that delay.</li>
</ol>
5. Determine Indifference Points at Each Delay
<ol>
	<li>Fully repeat Step 4 for each of the chosen delays, resetting the amount of the immediate outcome and the amount of the adjustment for the first trial at each delay.</li>
</ol>
6. Assess Delay Discounting of Qualitatively Different Outcomes (Optional)
<ol>
	<li>Ask the participant to provide an example of the chosen outcome. For example, if the chosen outcome is food then ask the participant &#34;What is your favorite food?&#34;</li>
	<li>Observe the participant&#39;s response and ask the participant how much a unit of the outcome costs (e.g., &#34;What is the cost of the preferred food?&#34;). 
	NOTE: If experimenters are interested in assessing differences in discounting across commodities, this step will equalize commodities in terms of value so that any differences in discounting are not due to differences in the amount being discounted.</li>
	<li>Display the values of the immediate and delayed starting values based on the price reported by the participant. Set the delayed amount of the outcome to be equal to the maximum value divided by the per unit price that was provided by the participant and then set the immediate alternative to &#189; of that amount. 
	NOTE: For example, if 1 serving of ice cream costs $5 and the maximum is $100 then there are 20 servings of ice cream in $100. Use this calculated value as the delayed alternative (e.g., &#34;20 servings of ice cream in 1 week&#34;) and &#189; of that amount as the immediate alternative (e.g., &#34;10 servings of ice cream now&#34;).</li>
	<li>Repeat all of Steps 4 and 5 with the recalculated value of each outcome.</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/53584/53584fig1.jpg" />
Figure 1.&#160;Trial Structure of the Adjusting Amount Task. The starting value for the delayed alternative, Y, should equal the maximum. The starting value for the immediate alternative, X, should equal .5Y. If X is chosen then the value of X should be decreased on the next trial. If Y is chosen then the value of X should be increased on the next trial. The amount of the adjustment is .25Y on Trial 1 and is .5 of the previous adjustment on each subsequent trial. <a href="https://www.jove.com/files/ftp_upload/53584/53584fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
7. Data Analysis
<ol>
	<li>Import data into any preferred data analysis program. Isolate the indifference point for each delay for each participant. Calculate the median indifference point for each delay for each group. 
	NOTE: Calculation of median indifference points is only necessary if a group design is used.</li>
	<li>Choose a curvilinear regression model (see representative results for examples). Use curvilinear regression to fit the model to the (median) indifference points. This will generate relevant parameter estimates for the selected model (see below for an explanation of the parameters). 
	NOTE: We have provided code to conduct curvilinear regression in Supplemental Materials for the statistical program R to aid the reader with Step 7.</li>
</ol>

<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>

The authors have nothing to disclose.

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.

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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 ...

measuring-delay-discounting-in-humans-using-an-adjusting-amount-task

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15.2K Views.  Utah State University. 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.

Video: Measuring Delay Discounting in Humans Using an Adjusting Amount Task

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 hand is touched. If the viewed and felt touches are given at the same time then this is sufficient to induce the compelling experience that the rubber hand is one's own hand. The RHI can be used to investigate exactly how the brain constructs distinct body representations for one's own body. Such representations are crucial for successful interactions with the external world. To obtain a subjective measure of the RHI, researchers typically ask participants to rate statements such as "I felt as if the rubber hand were my hand". Here we demonstrate how the crossmodal congruency task can be used to obtain an objective behavioral measure within this paradigm.
The variant of the crossmodal congruency task we employ involves the presentation of tactile targets and visual distractors. Targets and distractors are spatially congruent (i.e. same finger) on some trials and incongruent (i.e. different finger) on others. The difference in performance between incongruent and congruent trials - the crossmodal congruency effect (CCE) - indexes multisensory interactions. Importantly, the CCE is modulated both by viewing a hand as well as the synchrony of viewed and felt touch which are both crucial factors for the RHI.
The use of the crossmodal congruency task within the RHI paradigm has several advantages. It is a simple behavioral measure which can be repeated many times and which can be obtained during the illusion while participants view the artificial hand. Furthermore, this measure is not susceptible to observer and experimenter biases. The combination of the RHI paradigm with the crossmodal congruency task allows in particular for the investigation of multisensory processes which are critical for modulations of body representations as in the RHI.

We demonstrate how an objective measure can be employed in the widely employed rubber hand illusion paradigm. This measure is obtained by modifying the well-established crossmodal congruency task. This task allows the investigation of multisensory processes which are critical for modulations of body representations as in the rubber hand illusion.

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 hedonics, motivation, and goal value in more objective ways. This is particularly relevant for the understanding of overeating and obesity as well as their potential treatments. In this paper are described a set of measures of food-related motivation using handgrip force as a motivational measure. These methods can be used to examine changes in food related motivation with metabolic (satiety) and pharmacological manipulations and can be used to evaluate interventions targeted at overeating and obesity. However to understand food-related decision making in the complex food environment it is essential to be able to ascertain the reward goal values that guide the decisions and behavioral choices that people make. These values are hidden but it is possible to ascertain them more objectively using metrics such as the willingness to pay and a method for this is described. Both these sets of methods provide quantitative measures of motivation and goal value that can be compared within and between individuals.

This article describes a set of methods for the measurement of food related motivation and food related goal values 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 schizophrenia who are at familial high risk (FHR) may show similar cognitive and emotional changes. However, the neurological changes underlying the emergence of these symptoms remain unclear. This study sought to identify differences in frontal, striatal, and limbic regions in children and adolescents with FHR using functional magnetic resonance imaging. Groups of 21 children and adolescents at FHR and 21 healthy controls completed an emotional oddball task that relied on selective attention and the suppression of task-irrelevant emotional information. The standard oddball task was modified to include aversive and neutral distractors in order to examine potential group differences in both emotional and executive processing. This task was designed specifically to allow for children and adolescents to complete by keeping the difficulty and emotional image content age-appropriate. Furthermore, we demonstrate a technique for suitable fMRI registration for children and adolescent participants. This paradigm may also be applied in future studies to measure changes in neural activity in other populations with hypothesized developmental changes in executive and emotional processing.

This paper describes how to use the emotional oddball task and fMRI to measure brain activation in children and adolescents at familial high risk for schizophrenia (FHR).&#160;FMRI was used to measure differences in fronto-striato-limbic regions during an emotional oddball task. Children with FHR exhibited abnormal functional activation during adolescence.

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 diseases. The most widely used neuropsychological tests for the evaluation of attentional set-shifting in human subjects are the Wisconsin Card Sorting Test (WCST) and the CANTAB Intra-/Extra-dimensional set shift task (ID/ED). These tasks have proven clinical relevance and have been modified and successfully adapted for research in animal models. However, currently available tasks for rodents present several limitations, mainly due to their manual-based testing procedures, which are hampering translational advances in psychiatric medicine. To overcome these limitations and to better mimic the original version in primates, we present the development of a novel operant-based two-chamber ID/ED "Operon" task for rodents. We demonstrated the effectiveness of this novel task to measure different facets of cognitive flexibility in mice including attentional set formation and shifting, and reversal learning. Moreover, we show the high flexibility of this task in which three different perceptual dimensions can be manipulated with a high number of stimuli cues for each dimension. This novel ID/ED Operon task can be an effective preclinical tool for drug testing and/or large genetic screening relevant to the study of executive dysfunction and cognitive symptoms found in psychiatric disorders.

Attentional set-shifting cognitive abnormalities are a core feature of many psychiatric diseases. Here, we present the development of a novel automatic system for the effective study of attentional set-shifting abilities, executive functions and other cognitive abilities in mice with high translational validity to human studies.

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 potentially suitable therapeutic populations. The need to use a comprehensive battery of pain models is highlighted by studies whereby only a single pain model, thought to relate to the clinical situation, demonstrates lack of efficacy. No single experimental model can mimic the complex nature of clinical pain. The integrated, multi-modal pain task&#160;battery presented here encompasses the electrical stimulation task, pressure stimulation task, cold pressor task, the UVB inflammatory model which includes a thermal task and a paradigm for inhibitory conditioned pain modulation. These human pain models have been tested for predicative validity and reliability both in their own right and in combination, and can be used repeatedly, quickly, in short succession, with minimum burden for the subject and with a modest quantity of equipment. This allows a drug to be fully characterized and profiled for analgesic effect which is especially useful for drugs with a novel or untested mechanism of action.

Human pain models are valuable tools used to assess the analgesic potential of novel compounds and predict their clinical efficacy, especially when used in an integrated manner. Although implementation of these models is complex, with proper execution, the pain models described in this protocol can provide predictive and reliable results.

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 understanding of the neurobiological causes underlying the decision-making problems. A cost-benefit based T-maze task is used for measuring decision making in which rodents choose between a high reward arm (HRA) and a low reward arm (LRA). There are two paradigms of the T-maze decision-making task, one in which the cost is a time delay and the other in which it is physical effort. Both paradigms require a tedious and labor-intensive management of experimental animals, multiple doors, pellet reward, and arm choice recordings. In the current work, we invented an apparatus based on traditional T-maze with full automation for pellet delivery, door management and choice recordings. This automated setup can be used for the evaluation of both delay- and effort-based decision making in rodents. With the protocol described here, our lab investigated the decision-making phenotypes of multiple genetically modified mice. In the representative data, we showed that the mice with ablated medial habenular showed aversions of both delay and effort and tended to choose the immediate and effortless reward. This protocol helps to decrease the variability caused by experimenter intervention and to enhance experiment efficiency. In addition, chronic silicon probe or microelectrode recording, fiber-optic imaging and/or manipulation of neural activity can be easily applied during the decision-making task using the setup described here.

This article introduces an automated T-maze apparatus that we invented, and a protocol based on this apparatus for analyzing delay-based decision making 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 puff of air to the cornea). Eyeblink conditioning is often used experimentally to detect abnormalities in cerebellar-dependent learning and memory that underlies this type of associative learning. While experiments in adults and older children are relatively simple to administer using commercial equipment, eyeblink conditioning in infants is more challenging due to their poor compliance, which makes correct positioning of the equipment difficult. To achieve conditioning in one-year-old infants, a custom-made or an adapted commercial system can be used to deliver the air puff to the infant's cornea. The main challenge lies in successfully detecting and classifying the behavioral responses. We report that automated blink detection methods are unreliable in this population, and that conditioning experiments should be analyzed using frame-by-frame analysis of supplementary video camera recordings. This method can be applied to study developmental changes in eyeblink conditioning and to examine whether this paradigm can detect children with neurological disorders.

This protocol describes an eyeblink conditioning paradigm appropriate for experiments with one-year-old infants. Commercial or custom-made equipment can be used to deliver the stimuli, and data collection and analysis should be performed on the video recordings.

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. Touch that optimally activates CT fibers is consistently rated as hedonically pleasant. Patient groups with impaired social-emotional functioning also show disordered affective touch ratings. However, relying on self-reported ratings of touch has many limitations, including recall bias and communication barriers. Here, we describe a methodological approach to study affective responses to touch via facial electromyography (EMG) that circumvents the reliance on self-report ratings. Facial EMG is an objective, quantitative, and non-invasive method to measure facial muscle activity indicative of affective responses. Responses can be assessed across healthy and patient populations without the need for verbal communication. Here, we provide two separate datasets demonstrating that CT-optimal and non-optimal touch elicit distinct facial muscle reactions. Moreover, facial EMG responses are consistent across stimulus modalities, e.g. tactile (experienced touch) and visual (observed touch). Finally, the temporal resolution of facial EMG can detect responses on timescales that supersede that of verbal reporting. Together, our data suggest that facial EMG is a suitable methodology for use in affective tactile research that can be used to supplement, or in some cases, supplant, existing measures.

We describe a protocol to assess facial muscle activity in response to experienced and observed tactile stimulation using facial electromyography.

"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 automaticity of reading, language processing, and cognitive control, among others. When looking at bilingual individuals, this task can be used to obtain measures of language interference and control in both a bilingual&#39;s first language (L1) and second language (L2), as well as for testing the bilingual advantage hypothesis. The Stroop task presents participants with color terms written in congruent colors (e.g., the word RED written in red font), incongruent colors (e.g., the word RED written in green font), in addition to noncolor terms for control (e.g., the word TREE presented in any color), and uses the reaction times from the different conditions to assess the degree of interference and facilitation. In the covert version of the Stroop bilingual task (i.e., participants respond by pressing a button rather than naming aloud), stimuli in the L1 and the L2 are typically presented in separate blocks. While this allows for a simple, yet effective assessment of processing and cognitive control in each language, it fails to capture any potential differences in processing and control within bilingual young adult groups. The present task combines single-language blocks with a novel mixed-language block to increase the level of difficulty of the task, thus making it suitable for testing cognitive control in young adults. Representative results showing differences between performance in the single-language vs. mixed-language blocks are presented, and the benefits of a mixed-language block are discussed.

This bilingual Stroop task uses Congruent, Incongruent, and Neutral stimuli presented in blocks in the first language (L1) only, the second language (L2) only, and a combination of L1 and L2. This task allows for an examination of language processing and cognitive control in both L1 and L2.

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. Although direct behavioral observation may increase the external validity and generalizability of a study, it may be time-consuming and be subject to experimenter or observer bias. To address these issues, the use of data loggers as an alternative to natural observation can allow researchers to conduct broad studies without interrupting the participants&#39; naturally occurring behaviors. This article describes one of such tools&#8212;the occupancy and light data logger&#8212;with its technical description, deployment protocol, and information about its possible applications in psychological experiments. The results of testing the reliability of the logger in comparison to human observation is provided alongside an example of the gathered data during a 15-day measurement in public restroom (N = 1,148) that includes: 1) room occupancy changes; 2) indoor light changes; and 3) room occupancy time.

This article describes a procedure for using and deploying an occupancy and light data logger which allows collecting data about light-switching behavior of participants in field settings.

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