Return to the Alcohol Stroop Task - Keyboard page
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								* ALCOHOL STROOP TASK - with keyboard input*
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last updated:  03-12-2020 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC

Script Copyright © 03-12-2020 Millisecond Software

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BACKGROUND INFO 	
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This script implements an Alcohol themed Stroop task. The classic Stroop paradigm demonstrates the interference
of word meaning on naming the color in which the words are written as measured by reaction time/accuracy 
differences to color-meaning congruent and color-meaning incongruent combinations. 
The Alcohol Stroop takes advantage of this basic Stroop interference effect by comparing reaction times to
alcohol related words and neutral words.

The implemented procedure is based on:

Bauer, D. & Cox, W.M. (1998). Alcohol-relatedwords are distracting to both alcohol abusers and 
non-abusers in the Stroop colournaming task. Addiction, 93, 1539–42.

This script uses keyboard input instead of voice recordings.

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TASK DESCRIPTION	
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Participants are presented words from 4 different categories (alcohol, neutral, positive, negative) in four 
different  colors (blue, red, yellow, green) and are asked to press one of four response keys to indicate the 
color of the words  regardless of their meaning. At the end, participants are asked to rate how emotionally intense 
they would rate the words  (optional task).

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DURATION 
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the default set-up of the script takes appr. 12 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: 'alcoholstroopwithkeyboardinput_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 such as feedback trials. Thus, trialnum 
										may not reflect the number of main trials run per block.
									
values.target:						the currently selected target word
values.color:						the currently selected color
stimulusitem:						stimulusitem in the order presented
response:							the participant's response (scancode of responsekey)

										scancode/label for the red response button (default: 32 -> d)
										scancode/label for the green response button (default: 33 -> f)
										scancode/label for the blue response button (default: 36 -> j)
										scancode/label for the yellow response button (default: 37 -> k)

correct:							the correctness of the response (1 = correct; 0 = incorrect)
latency: 							the response latency (in ms); measured from onset of word

values.correct_Alcoholwords - 
values.correct_positivewords:		sum up the correct responses in each category across blocks	


(2) Summary data file: 'alcoholstroopwithkeyboardinput_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)
									
values.correct_Alcoholwords - 
values.correct_positivewords:			sum up the correct responses in each category across blocks
		
expressions.meanrt_alcoholwords:		mean latency of correct responses to Alcohol words across blocks
expressions.meanrt_negativewords:		mean latency of correct responses to negative words across blocks
expressions.meanrt_neutralwords:		mean latency of correct responses to neutral words across blocks
expressions.meanrt_positivewords:		mean latency of correct responses to positive words across blocks

expressions.interference_alcohol:  			Difference btw. mean reaction time to alcohol and neutral words (latencies of correct responses only)
													=> positive: meaning of Alcohol words interfered more than meaning of neutral words on color categorization task

expressions.interference_negativewords: 	Difference btw. mean reaction time to negative words and neutral words (latencies of correct responses only)
													=> positive: meaning of Negative words interfered more than meaning of neutral words on color categorization task

expressions.interference_positivewords:		Difference btw. mean reaction time to positive words and neutral words (latencies of correct responses only)
													=> positive: meaning of Positive interfered more than meaning of neutral words on color categorization task
								
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EXPERIMENTAL SET-UP 
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4 categories (alcohol words, positive words, negative words, neutral words) tested within subjects

1. Practice Block: 24 trials (this script uses the words "one" to "ten" as practice stimuli)
2. 2 x Test Block: 2x160 trials (= 4 categories x 10 stimuli per category x 4 repetitions); 
	* order is randomly determined
	* colors are randomly sampled for each word (Constraint: all colors appear equally often for each category)
	Note: repeat words can repeat colors)
	* fixation cross is presented for 500ms (default) -> target words are presented for a maximum of 1500ms (=response window)
	* error feedback given; to remove follow instructions under TRIALS
3. In between the two Testblocks: 2min Rest period (optional, go to Editable Parameters-> Editable Values)
4. Ratings (optional, go to Editable Parameters -> Editable Values)

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STIMULI
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* original stimuli by Bauer & Cox (1998), can be edited under section EDITABLE STIMULI

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INSTRUCTIONS 
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not original; can be easily altered 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:

/skiprating:								0 = likert ratings are run (default); 1 = likert ratings are skipped
/skiprest:									0 = rest block is run (default) ; 1 = rest block is skipped

Durations:
/maxtargetpresentationtime:					maximum time that target words are presented on screen (default: 1500ms)
/fixationcrosspresentationtime:				time that fixation cross is presented (default: 500ms)
/posttrialpause:							pause after each stroop trial (default: 0ms)
/restduration:								time to rest between stroop blocks (default: 120000ms)

Responsekeys:
/keyred:									the red response button (default: "D")
/keygreen:									the green response button (default: "F")
/keyblue:									the blue response button (default: "J")
/keyyellow:									the yellow response button (default: "K")

the four colors used in this script:
/color1 = red
/color2 = green
/color3 = blue
/color4 = yellow