The Multiple Price List Task measures delay discounting, which is the tendency to discount value in the future (e.g., a lower subjective value of money at a later date relative to an earlier date). This tendency is often reflected by a preference for small rewards received sooner over larger rewards received later. In this task, participants make 48 decisions. Twenty-four of these decisions are in the gains domain, and 24 decisions are in in the losses domain. These decisions occur for three compared times: (1) 2 vs. 4 weeks from today, (2) today vs. 4 weeks from today, and (3) today vs. 2 weeks from today. In the gains domain, participants choose between a smaller, sooner reward, or a larger, later reward. The early amount gained is always 400 KSH (a monetary unit equivalent to ~4 USD), and the later amount gained is either 340 KSH, 400 KSH, 440 KSH, 500 KSH, 700 KSH, 800 KSH, 1,200 KSH, or 1,600 KSH. In the losses domain, participants are given a 1,600 KSH endowment to start with, and are asked to choose between a smaller, sooner loss or a larger, later loss. Parallel to the amounts added in the gains domain, for the losses domain, the early amount subtracted is always 400 KSH (a monetary unit), and the later amount subtracted is either 340 KSH, 400 KSH, 440 KSH, 500 KSH, 700 KSH, 800 KSH, 1,200 KSH, or 1,600 KSH. The Multiple Price List task is designed to measure parameters of a discounting model on an individual level. Participants are assumed to discount the future in a quasi-hyperbolic way (Laibson, 1997) and be utility-maximizing. If this is true and utility is linear in income, then the points at which participants switch from accepted the early payment/loss to the later payment/loss or vice versa identify their precise discounting function. This function is characterized by two parameters. The first is a discounting parameter, commonly referred to by the Greek letter delta, which indicates the rate at which the subjective value of monetary rewards declines over time. For example, if a participant is indifferent between 400 KSH tomorrow and 800 KSH in two days, their decision would be characterized by a discount parameter of 0.5. The other parameter, often represented by the Greek letter beta, characterizes present-biasedness. Present-bias is the tendency for monetary rewards now to be higher in subjective value than those at any future date, regardless of how soon the “future” is. This parameter is estimated by dividing the discount rate in the near frame (today vs. 2 weeks from today) by the discount rate in the far frame (2 weeks from today vs. 4 weeks from today). These parameters are measured separately for each participant separately in the gains and losses domains.
The Multiple Price Lists Task is a measure of delay discounting (Coller & Williams, 1999), the tendency for people to prefer smaller, immediate monetary rewards over larger, delayed rewards (Kirby & Maraković, 1996). The construct of temporal discounting is important to measure as a potential self-regulatory mechanism of behavior change because it has been shown that a greater preference for temporally close smaller rewards over temporally distant larger rewards is related to real-world behaviors such as greater drug use, lower exercise, and lower safety behaviors such as the tendency to wear a seat belt (Daugherty & Brase, 2010). This pattern of findings supports the proposal that a greater preference for smaller rewards in the short-term over larger rewards in the long-term reflects higher impulsivity and lower self-regulatory control (Odum, 2011).
[+] PMCID, PUBMED ID, or CITATION
Text Citation: Daugherty, J. R., & Brase, G. L. (2010). Taking time to be healthy: Predicting health behaviors with delay discounting and time perspective. Personality and Individual differences, 48(2), 202-207.
Text Citation: Coller, M., & Williams, M. (1999). Eliciting Individual Discount Rates. Experimental Economics, 2, 107–127.
Text Citation: Kirby, K. N., & Maraković, N. N. (1996). Delay-discounting probabilistic rewards: Rates decrease as amounts increase. Psychonomic Bulletin & Review, 3(1), 100-104.
Text Citation: Laibson, D. (1997). Golden eggs and hyperbolic discounting. The Quarterly Journal of Economics, 112(2), 443-478.
Text Citation: Odum, A. L. (2011), Delay Discounting: I'm a K, you’re a K. Journal of the Experimental Analysis of Behavior, 96, 427–439.
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The Science of Behavior Change (SOBC) program seeks to promote basic research on the initiation, personalization and maintenance of behavior change. By integrating work across disciplines, this effort will lead to an improved understanding of the underlying principles of behavior change. The SOBC program aims to implement a mechanisms-focused, experimental medicine approach to behavior change research and to develop the tools required to implement such an approach. The experimental medicine approach involves: identifying an intervention target, developing measures to permit verification of the target, engaging the target through experimentation or intervention, and testing the degree to which target engagement produces the desired behavior change.
Within the SOBC Measures Repository, researchers have access to measures of mechanistic targets that have been (or are in the processing of being) validated by SOBC Research Network Members and other experts in the field. The SOBC Validation Process includes three important stages of evaluation for each proposed measure: Identification, Measurement, and Influence.
The first stage of validation requires a measure to be Identified within the field; there must be theoretical support for the specific measure of the proposed mechanistic target or potential mechanism of behavior change. This evidence may include references for the proposed measure, or theoretical support for the construct that the proposed measure is intended to assess. The second stage of validation requires demonstration that the level and change in level of the chosen mechanistic target can be Measured with the proposed measure (assay). For example, if the proposed measure is a questionnaire, the score on the measure should indicate the activity of the target process, and it must have strong psychometric properties. The third stage of validation requires demonstration that the measure can be Influenced; there must be evidence that the measured target is malleable and responsive to manipulation. Evidence relating to each stage includes at least one peer-reviewed publication or original data presentation (if no peer-reviewed research is available to support the claim) and is evaluated by SOBC Research Network Members and experts in the field.
Once a measure has gone through these three stages, it will then either be Validated or Not validated according to SOBC Research Network standards. If a measure is Validated, then change in the measured target was reliably associated with Behavior Change. If a measure is Not validated, then change in the measured target was not reliably associated with Behavior Change. Why would we share measures that are not validated? The SOBC Research Network values open, rigorous, and transparent research. Our goal is to make meaningful progress and develop replicable and effective interventions in behavior change science. Therefore, the SOBC sees value in providing other researchers in the field with information regarding measures that work and measures that fall short for specific targets. Further, a measure that is not validated for one target in one population may be validated in another target or population.
Want to learn more? For any questions regarding the SOBC Validation Process or Measures Repository, please email email@example.com.
Has the mechanism been identified as a potential target for behavior change? This section summarizes theoretical support for the mechanism.
Have the psychometric properties of this measure been assessed? This section includes information such as content validity, internal consistency, and test-retest reliability.
Has a study manipulation led to change in the mechanism? This section addresses evidence that this measure is modifiable by experimental manipulation or clinical intervention.
Has a change in this mechanism been associated with behavior change? This section addresses empirical evidence that causing change in the measure reliably produces subsequent behavior change.