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										Minute Discounting Task
SCRIPT INFO

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

Script Copyright © 03-06-2018 Millisecond Software


BACKGROUND INFO 

											*Purpose*
This script implements the Minute Discounting Task described by:

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.

The Minute Discounting Tasks, an adjusting delay task, offers a quick way to estimate discount rates.


											  *Task*
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.


DATA FILE INFORMATION: 
The default data stored in the data files are:

(1) Raw data file: 'minutediscounting_raw*.iqdat' (a separate file for each participant)*

build:							Inquisit build
computer.platform:				the platform the script was run on
date, time, subject, group:		date and time script was run with the current subject/groupnumber 
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) 
									
/delayedAmount:					the promised delayed amount (default: $10)
/immediateAmount:				the promised immediate amount (default: $5)
/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)
									Effective Delay 50% (ED50): can be directly translated into k-values
/k:								stores the absolute k-value (discount rate, inverse of ED50) 


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

script.startdate:				date script was run
script.starttime:				time script was started
script.subjectid:				subject id number
script.groupid:					group id number
script.elapsedtime:				time it took to run script (in ms)
computer.platform:				the platform the script was run on
/completed:						0 = script was not completed (prematurely aborted); 1 = script was completed (all conditions run)
/delayedAmount:					the promised delayed amount (default: $10)
/immediateAmount:				the promised immediate amount (default: $5)
/ED50:							stores the estimated ED50 (in days)
									Effective Delay 50% (ED50): can be directly translated into k-values
/k:								stores the absolute k-value (discount rate, inverse of ED50) 
/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


EXPERIMENTAL SET-UP

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 values used in this script 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.
	

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:

/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
								
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