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										Minute Discounting Task
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 03-06-2018
last updated:  11-20-2019 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC

Script Copyright © 11-20-2019 Millisecond Software

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BACKGROUND INFO 	
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This script implements the Minute Discounting Task; a quick procedure to estimate delay discount rates of monetary rewards.
Instead of adjusting the amounts and keeping delay intervals constant, the Minute Discounting Tasks adjusts the 
delays.

The implemented procedure is described in:

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, 222–228.

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TASK DESCRIPTION	
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Participants receive 5 questions that ask whether they prefer a smaller amount (default: $5) now
or a larger amount (default: S10) at variable delays (delays depend on previous choices).
The task takes about a minute. The discount rate k is calculated.

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DURATION 
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the default set-up of the script takes appr. 1 minute 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: 'minutediscounting_raw*.iqdat' (a separate file for each participant)*

build:							The specific Inquisit version used (the 'build') that was run
computer.platform:				the platform the script was run on (win/mac/ios/android)
date, time, 						date and time script was run 
subject, group, 					with the current subject/groupnumber
script.sessionid:					with the current session id

blockcode, blocknum:				the name and number of the current block (built-in Inquisit variable)
trialcode, trialnum: 				the name and number of the currently recorded trial (built-in Inquisit variable)
										Note: trialnum is a built-in Inquisit variable; it counts all trials run; even those
										that do not store data to the data file. 

parameters.immediateAmount:		the promised immediate amount (default: $5)										
parameters.delayedAmount:		the promised delayed amount (default: $10)


trialCount:						a running count of the choice trials run
choiceNo:						stores the current choice trial number (1-5) attached to the current index (should always be equal to the number of choice trials run = values.trialcount)
index:							the index of the current choice values (choice trial #1 starts with index = 16)
indexAdjustment:					the current index adjustment value
delayChoice:						the variable delay choice assigned to the current index
 
response:						the participant's response: selected response button "now" vs. "delayed"
latency: 							the response latency (in ms); measured from: onset of response buttons

ED50:							stores the estimated ED50 (in days) ~ the number of days that a delay is tolerated to receive the higher payoff
								Effective Delay 50% (ED50): can be directly translated into k-values
								
k:								Main DV = stores the absolute k-value (discount rate, inverse of ED50) 
								The higher the discount rate, the less participant is willing to wait for the delayed higher reward
								and the more the lesser, immediate reward is preferred.
																

(2) Summary data file: 'minutediscounting_summary*.iqdat' (a separate file for each participant)*

computer.platform:				the platform the script was run on (win/mac/ios/android)
script.startdate:					date script was run
script.starttime:					time script was started
script.subjectid:					assigned subject id number
script.groupid:					assigned group id number
script.sessionid:					assigned session id number
script.elapsedtime:				time it took to run script (in ms); measured from onset to offset of script
script.completed:					0 = script was not completed (prematurely aborted); 
								1 = script was completed (all conditions run)

parameters.immediateAmount:		the promised immediate amount (default: $5)										
parameters.delayedAmount:		the promised delayed amount (default: $10)

ED50:							stores the estimated ED50 (in days) ~ the number of days that a delay is tolerated to receive the higher payoff
								Effective Delay 50% (ED50): can be directly translated into k-values
								
k:								Main DV = stores the absolute k-value (discount rate, inverse of ED50) 
								The higher the discount rate, the less participant is willing to wait for the delayed higher reward
								and the more the lesser, immediate reward is preferred.
								
meanRT:						the mean choice reaction time (measured from onset of the response buttons)

* separate data files: to change to one data file for all participants (on Inquisit Lab only), go to section
"DATA" and follow further instructions


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EXPERIMENTAL SET-UP 
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1 Test block with 5 choice trials
* each trial presents a choice between the immediate amount and the delayed amount
=> based on response the new delay gets selected for the next trial based on 
adjusting the index of the selected delays (see item.delayChoices under section STIMULUS)
* delay parameters used in this script to calculate the discount rate k are published in: Koffarnus & Bickel (2014, Table 1, p.224)

Adjustment Rule of the indices:
* the first delay always uses index = 16 ("3 weeks")
* the index adjustment value starts at 16/2=8 and is halved for each new trial (8, 4, 2, 1)
* if the immediate amount is selected: the index is adjusted down by the current adjustment value
* if the delayed amount is selected: the index is adjusted up by the current adjustment value
Example: 
* the index adjust amount in trial 1 = 8:
	if the immediate amount is selected in trial 1 (index always 16), trial 2 presents the delay for index 8 (16-8) ("1 day")
	if the delayed amount is selected in trial 1 (index always 16), trial 2 presents the delay for index 24 (16 + 8) ("2 years")

* the index adjust amount in trial 2 = 4:
	if the immediate amount is selected in trial 2 (e.g. index 8), trial 3 presents the delay for index 4 (8-4)("4 hours")
	if the delayed amount is selected in trial 2 (e.g. index 8), trial 3 presents the delay for index 12 (8 + 4)("4 days")
etc.

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INSTRUCTIONS 
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provided by Millisecond Software - can be edited under section Editable Instructions

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EDITABLE CODE 
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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:

/delayedAmount:					the promised delayed amount (default: $10)
/immediateAmount:				the promised immediate amount (default: $5)

/iti:								the intertrial interval between each choice trial (default: 1000)
								Note: the options are blacked out during the iti