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*ABCD Adjusting Amount Discounting Procedure*
(Tablet Version)
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 04-28-2017
last updated: 05-30-2023 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 05-30-2023 Millisecond Software
This script has been made available to the Millisecond Software Library by the ABCD Research Consortium.
This script is designed to be run on ipads for in person testing. The ABCD smartphone version for remote
testing is also available in the Millisecond library.
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BACKGROUND INFO
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This script implements an Adjusting Amount Discounting Procedure
to assess the hypothetical reward amounts at which people start to discount higher monetary rewards
in favor of shorter wait periods.
This script is based on an Python script written by Dr. Mikhail Koffarnus and
generously shared by the ABCD Consortium.
References:
Koffarnus, M.N. & and Warren K. Bickel, W.K. (2014). A 5-Trial Adjusting Delay Discounting Task:
Accurate Discount Rates in Less Than One Minute.
Experimental and Clinical Psychopharmacology, 22, No. 3, 222–228
Rule Violations described in:
Johnson and Bickel (2008, Experimental and Clinical Psychopharmacology, 16, 264-274).
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TASK DESCRIPTION
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Participants have to make a choice between 2 amounts of moneys with different delays:
a delayed amount (here: $100) for delay1 (e.g. "in a year") compared to an immediate amount (e.g. $50)
right now. Seven delays ("6hours", "1 day", "1 week", "1 month", "3 months", "1 year", "5 years")
are tested in this script to determine 7 indifference points. Each delay is tested with 6 trials.
Depending on the participant's choice the immediate amount is adjusted up (when delayed amount is selected)
or down (when immediate amount is chosen.)
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DURATION
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the default set-up of the script takes appr. 5 minutes to complete
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DATA FILE INFORMATION
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The default data stored in the data files are:
(1) Raw data file: 'abcdadjustingamountdiscounting_tablet_raw*.iqdat' (a separate file for each participant)*
build: Inquisit build
computer.platform: the platform the script was run on (win/mac/ios/android)
date, time, subject, group: date and time script was run
subject, group, session: with the current subject/groupnumber/session number
blockcode, blocknum: the name and number of the current block
trialcode, trialnum: the name and number of the currently recorded trial
(Note: not all trials that are run might record data; by default data is collected unless /recorddata = false is set for a particular trial/block)
countDelays: counts the number of delays tested
delayIndex: index of delay (in ascending order)
delay: stores the current delay tested: ("6 hours from now", "1 day", "1 week", "1 month", "3 months", "1 year", "5 years")
delay_indays: stores the current delays in unit 'day' (numbers from original Phython program)
countTrials: counts the number of adjustment trials run per block
delayedReward: the delayed amount in $ (here: 100)
immediate: stores the currently tested 'immediate' amount
delayedLocation: 1 = delayed amount is presented on the left; 2 = delayed amount is presented on the right
stimulusitem: the presented stimuli in order of trial presentation
text.delayed.timestamp: the elapsed script time when delayed text was presented
choiceRT: the choice RT (in ms); measured from onset of choices
homeButtonRT: the time (in ms) that it took to press the green home Button before the choice trial
response: the participant's response (for test trials: immediate vs. delayed)
adjust: stores the adjust amount of the next immediate amount
nextimmediate: stores the next 'immediate' amount
lastImmediateChosen: stores the last immediate amount chosen
lastImmediateRejected: stores the last immediate amount rejected
IndiffPoint: calculates the current indifference point as the midpoint of values.last ImmediateChosen and values.lastImmediateRejected
in proportion to parameters.delayedRewardAmount; indifference point is stored as a %
and its value directly translate to the corresponding $ value (as the standard amount is $100)
/immediateChoiceValidity: immediate choice validity questions after: 3 months, 1 year, 5 year
("get $100 NOW" vs. "get $100 in 5 years")
each immediate choice receives 1 point: max points 3
(2) Summary data file: 'abcdadjustingamountdiscounting_tablet_summary*.iqdat' (a separate file for each participant)*
inquisit.version: Inquisit version run
computer.platform: the platform the script was run on (win/mac/ios/android)
startDate: date script was run
startTime: time script was started
subjectid: assigned subject id number
groupid: assigned group id number
sessionid: assigned session id number
elapsedTime: time it took to run script (in ms); measured from onset to offset of script
completed: 0 = script was not completed (prematurely aborted);
1 = script was completed (all conditions run)
delayed: the delayed amount in $ (here: 100)
testedDelays: a string variable that stores all tested delays in the order tested
immediateChoiceValidity: immediate choice validity questions after: 3 months, 1 year, 5 year
("get $100 NOW" vs. "get $100 in 5 years")
each immediate choice receives 1 point: max points 3
Indif_Point_6h-
Indif_Point_5years: store the Indifference Points (IP) for the 7 specific delays tested in this script
(the values are stored as % in relation to standard value and the values directly translates to
the corresponding $ value - as the standard amount is $100)
Johnson & Bickel (2008)-test for rule violations:
Consistent_per_JBcriterion1: no: at least one indifference point is larger than the preceding one by 20% of delayed amount (here: $100)
yes: otherwise
JBPass1_NumberViolations: stores the number of rule violations of JB criterion 1 based on the six individual indifference point checks
(Range: 0 - 6)
Consistent_per_JBcriterion2: no: the difference btw. first and last indifference point (set relative to delayed amount) is smaller than 10% of the delayed standard amount
yes: otherwise
meanRT_allChoices: mean latency (in ms) of all choices
medianRT_allChoices: median latency (in ms) of all choices
meanRT_immedChoices: mean latency (in ms) of 'immediate' choices
medianRT_immedChoices: median latency (in ms) of 'immediate' choices
meanRT_delayedChoices: mean latency (in ms) of 'delayed' choices
medianRT_delayedChoices: median latency (in ms) of 'delayed' choices
* separate data files: to change to one data file for all participants (on Inquisit Lab only), go to section
"DATA" and follow further instructions
EXPERIMENTAL SET-UP
* 7 delays ("6hours", "1 day", "1 week", "1 month", "3 months", "1 year", "5 years") are tested within-participants in a blocked design
Note: the delays can be adjusted under section Editable Lists (names of IP values will then have to be adjusted under section VALUES)
* the order of the delays is determined randomly
* 6 trials per delays
* the delayed amount can be set under Editable parameters. By default, it's $100
* the starting immediate amount is set as half of the delayed amount
* immediate choice validity questions after delays: "3months", "1year", "5years"
("get $100 NOW" vs. "get $100 in 5 years")
each immediate choice receives 1 point: max points 3
Trials:
* left or right screen location of the delayed and immediate amount are randomly determined for each trial
(maxrun of one side = 3 per block)
* participants makes a choice via a button press: the left key refers to selecting the choice on the left,
the right key refers to selecting the choice on the right
* participants have an unlimited time to make a choice
* depending on choice
Adjustment Algorithm of the Immediate Amount:
First Trial: half of the difference of delayed and immediate amount
Example: delayed amount = 100; immediate amount = 50; adjustment = (100-50)/2 = 25
if participants chooses delayed amount (100) -> the next immediate amount tested is = 50 + 25 = 75
if participant chooses immediate amount (50) -> the next immediate amount tested is = 50 - 25 = 25
Subsequent Trials: half of the previous used adjustment
Example: previous adjustment = 25 => the next adjustment will be 12.5
Algorithm to calculate Indifference Points (P):
at the end of each delay, the computer calculates the indifference point for the tested delays
as the midpoint of last 'immediate' amount chosen and last 'immediate' amount rejected.
Notes:
a) if participant always rejects the immediate amount, the IP will be the midpoint between the
delayed amount and the last immediate amount rejected.
b) if participant always rejects the delayed amount, the IP will be the midpoint between
0 and the last immediate amount chosen
Rule Violation Algorithms (Johnson & Bickel, 2008):
Johnson and Bickel (2008, Experimental and Clinical Psychopharmacology, 16, 264-274).
JB Rule1: if a later indifference point (absolute indifference points) is larger than the preceding one by 20% of the delayed standard amount=> rule violation
JB Rule2: if the difference btw. first and last indifference point (absolute indifference points) is smaller than 10% of the standard amount => rule violation
Note: the 'absolute' indifference points in this script are the ones not set relative to the delayedRewardAmount
SECRET SWIPE:
put your finger in the middle of the screen and move upwards (stop movement on screen - do not go over the top of the screen)
INSTRUCTIONS
provided by Millisecond Software - can be edited under section Editable Instructions
EDITABLE CODE:
check below for (relatively) easily editable parameters, stimuli, instructions etc.
Keep in mind that you can use this script as a template and therefore always "mess" with the entire code to further customize your experiment.
The parameters you can change are:
/delayedRewardAmount: the delayed amount in $ (here: 100)
/starttrialDuration: the duration (in ms) of the start trial in each block (the announcement of the particular delay) (default: 2000ms)
/leftx: the proportional screen position of the left amount (here: 25% of the width of the canvas) note: 0% is the very left of canvas
/rightx: the proportional screen position of the right amount (here: 75% of the width of the canvas): 100% is the very right of canvas
/test_setting = "remote" (don't change)
