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

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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. ...