Delay Discounting Task - Short Term

Technical Manual

Script Author: David Nitz (nitz.david@gmail.com), Millisecond.

Last Modified: January 12, 2025 by K. Borchert (katjab@millisecond.com), Millisecond

Background

The Delayed Reward Task by Cherek et al (1997) is a 2-choice procedure for assessing tolerance for delayed rewards. It can be used as a measure of impulsivity.

References

Cherek, D. R., Moeller, F. G., Dougherty, D. M., & Rhoades, H.(1997). Studies of violent and nonviolent male parolees: II. Laboratory and psychometric measurements of impulsivity. Biological Psychiatry, 41, 523-529.

Related References:

Cherek, D. R., Moeller, F. G., Schnapp, W., & Dougherty, D. M. (1997). Studies of violent and nonviolent male parolees: I. Laboratory and psychometric measurements of aggression. Biological Psychiatry, 41, 514-522.

Moeller, F. G., Dougherty, D. M., Barratt, E. S., Oderinde, V., Mathias, C. W., Harper, R. A., & Swann, A. C. (2002). Increased impulsivity in cocaine dependent subjects independent of antisocial personality disorder and aggression. Drug and Alcohol Dependence, 68, 105-111.

Duration

18 minutes

Description

Participants get to choose between an A button (small with small, fixed delay) or a B button (big with large, variable delay).

Procedure

During experimental sessions subjects were provided with two response options: 1) an
impulsive response option (option A); and 2) a self-control response option (option B).

Training Sessions:

At the beginning of the first session, subjects participated in a training session that consisted of 20
trials. During the first 10 trials the letter A was presented on the computer screen, and after
a 5-sec delay the letter A began to flash off and on. A single press of button A removed the
letter from the screen and added 5 cents to the counter (00.05). During the last 10 trials, the
letter B appeared, and 15 sec later the letter began to flash off and on. A single press of
button B removed the letter from the screen and added 15 cents to the counter (00.15). At
the end of the 20 training trials, the screen displayed "Training Over." The purpose of the
training sessions was to give subjects a brief exposure to the different monetary amounts and
delays associated with the letters A and B.

Test Sessions:

During these subsequent regular sessions, both the A and B letters appeared on the screen at
the beginning of each trial. The subject selected a letter by pressing the corresponding button,
either A or B. The selected letter remained on the screen, and the other letter disappeared.
After a delay, the letter began to flash off and on, and single response on that button added a
monetary value (either 5 or 15 cents) to the counter, and the letter disappeared.
The subsequent appearance of the two letters signaled the beginning of the next trial.
The letter A selection resulted in a 5-cent reward after a fixed delay of 5 sec.
The letter B selection resulted in a 15-cent reward after a delay that began each session at
15 sec. The delay for option B varied during the session. Each time the subject selected option
B, the next delay increased by 2 sec. Conversely, each time the subject selected option A, the
next delay for option B decreased by 2 sec. The delay for option B was never less than 7 sec,
and was thus always longer than the delay for option A, which was fixed at 5 sec. Since the
sessions were stopped after 60 trials, the length of the sessions varied depending upon the
choices of the subjects.

Instructions

see section Editable Instructions

Summary Data

File Name: delayedrewardtask_cherek_summary*.iqdat

Data Fields

Name	Description
inquisit.version	Inquisit version number
computer.platform	Device platform: win \| mac \|ios \| android
computer.touch	0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities
computer.hasKeyboard	0 = no external keyboard detected; 1 = external keyboard detected
startDate	Date the session was run
startTime	Time the session was run
subjectId	Participant ID
groupId	Group number
sessionId	Session number
elapsedTime	Session duration in ms
completed	0 = Test was not completed 1 = Test was completed
totalReward	Total amount of money rewarded (separate counts for training and test sessions).
impulsiveChoices	Running total of impulsive choices (applies to test sessions only).
controlledChoices	Running total of controlled choices (applies to test sessions only).
pctimpulsive	Proportion impulsive choices in test session
pctControlled	Proportion controlled choices in test session
meanDelaysControlled	The mean delay (in s) for choosing the delayed choice Range: 7.333s (choosing only impulsive choice)- 30.5s (choosing only controlled choice)

Raw Data

File Name: delayedrewardtask_cherek_raw*.iqdat

Data Fields

Name	Description
build	Inquisit version number
computer.platform	Device platform: win \| mac \|ios \| android
computer.touch	0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities
computer.hasKeyboard	0 = no external keyboard detected; 1 = external keyboard detected
date	Date the session was run
time	Time the session was run
subject	Participant ID
group	Group number
session	Session number
blockcode	The name the current block (built-in Inquisit variable)
blocknum	The number of the current block (built-in Inquisit variable)
trialcode	The name of the currently recorded trial (built-in Inquisit variable)
trialnum	The number of the currently recorded trial (built-in Inquisit variable) trialnum is a built-in Inquisit variable; it counts all trials run even those that do not store data to the data file.
nTrials	Number of trials (separate counts for training and test sessions).
response	Participant’s response (choice trials: A or B)
latency	Latency for the current trial (in ms)
aDelay	Fixed delay in milliseconds for impulsive choices (option A). Default is 5000.
bDelay	Delay in milliseconds for controlled choices (option B) at the start of the session. Default is 15000. The delay is adjusted at runtime according to subjects' responses.
totalReward	Total amount of money rewarded (separate counts for training and test sessions).
impulsiveChoices	Running total of impulsive choices (applies to test sessions only).
controlledChoices	Running total of controlled choices (applies to test sessions only).
pctimpulsive	Proportion impulsive choices in test session
pctControlled	Proportion controlled choices in test session

Parameters

The procedure can be adjusted by setting the following parameters.

Name	Description	Default
skipTraining	Pseudo-boolean switch to (de-)activate the training block. 1 = no training block; 0 = run training block.	0
skipTest	Pseudo-boolean switch to (de-)activate the test block. 1 = no test block; 0 = run test block.	0
aDelay	Fixed delay in milliseconds for impulsive choices (option A).	5000
bDelay	Delay in milliseconds for controlled choices (option B) at the start of the session. The delay is adjusted at runtime according to subjects' responses.	15000
bDelaymin	Minimum value for the controlled choice delay. This value is used in the runtime adjustments and should be greater than the fixed impulsive choice delay ('parameters.adelay').	7000
bAdjust	Amount in milliseconds by which the controlled choice delay is adjusted. If subjects choose the 'controlled' option (B), the controlled choice delay is increased by the value entered here. If subjects choose the 'impulsive' option (A), the controlled choice delay is decreased by the value entered here.	2000
aReward	Fixed reward for impulsive choices.	0.05
bReward	Fixed reward for controlled choices.	0.15