Return to the Evaluative Priming Task page
___________________________________________________________________________________________________________________	

									Evaluative Priming Paradigm - Template
___________________________________________________________________________________________________________________	

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 09-19-2019
last updated:  11-11-2019 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC

Script Copyright © 11-11-2019 Millisecond Software

___________________________________________________________________________________________________________________
BACKGROUND INFO 	
___________________________________________________________________________________________________________________	

This script implements a template for the Evaluative Priming Paradigm to study implicit attitudes.
The implemented procedure is based on Fazio et al (1995) who used this paradigm to study implicit 
racial biases. Due to the sensitive nature of their study, their design utilized deception to distract participants from 
the true purpose of the study and included several phases such as a memory test for
faces that were not central to the research question.

This script implements a template for the relevant phases only. The target categories under investigation are
"flowers" and "insects". Filler categories "cars" and "appliances" are used to "obscure" the study of 
attitudes towards flowers and insects in this template script.

In general, priming procedures are simple response-timed binary categorization tasks of items from two target
categories  (e.g. positive vs. negative adjectives). Priming Procedures are based on the assumption that 
people respond faster if the target category was already 'mentally activated' by briefly presenting items 
(called 'primes') that are closely connected in one's mind. For example, a person should be faster to quickly 
categorize the target word 'good' as 'positive' after the brief presentation of the prime word 'ice-cream' than
after the brief presentation of the prime word 'famine'. Priming Procedure can thus be used to study 
implicit attitudes. Faster reaction times to targets after primes from a specific category are interpreted 
as indicative of an existing  relationship/association between  the categories in the person's mind.

If the primes are presented with a temporal duration that can be consciously processed, the primes are
called 'supraliminal'. If the duration of the primes is so short that they are outside one's conscious 
awareness the primes are called 'subliminal'. This script uses supraliminal primes in the form of images.

The Evaluative Priming Task provides individual "response time facilitation scores" for each of the primes under
investigation. Positive facilitation scores imply that the prime sped up the categorization of the positive(negative)
adjective. Negative facilitation scores imply that the prime  slowed down the categorization of the positive(negative).


Reference

Fazio, R.H., Jackson, J.R. Dunton, B.C. & Williams, C.J. (1995). Variability in Automatic Activation as an
Unobtrusive Measure of Racial Attitudes: A Bona Fide Pipeline? Journal of Personality and Social Psychology,
69, 1013-1027.
___________________________________________________________________________________________________________________
TASK DESCRIPTION	
___________________________________________________________________________________________________________________	

Baseline Phase: 
Participants categorize positive and negative adjectives using two different keys on the keyboard

Test Phase:
Participants categorise positive and negative adjectives using two different keys on the keyboard.
The adjectives ("targets") are preceded by images of flowers, insects, cars or appliances ("primes").

___________________________________________________________________________________________________________________	
DURATION 
___________________________________________________________________________________________________________________	
the default set-up of the script takes appr. 12 minutes to complete

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

(1) Raw data file: 'evaluativepriming_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. 	

ABpair1_stimuli- 
ABpair1_stimuli:					store the itemnumbers of the matched category A and category B stimuli for each item pair
								Example: AB pair1 Stimuli = "catA:3,catB:5" 
								=> itemnumber 3 of category A was matched with itemnumber 5 of category B
																		
primeCategory: 					"catA" (here: flowers),
								"catB" (here: insects)
								 "catC" (here: cars)
								 "catD" (here: appliances)
								 
targetValence: 					"positive" vs. "negative"
selectPrime:						the itemnumber of the currently presented prime 
prime: 							the currently presented prime
selectTarget: 						the itemnumber of the currently presented target
target: 							the currently presented target

response:						the participant's response (scancode of response buttons)
									18 = E
									23 = I

responseCat:						the interpreted response: "positive" vs. "negative"																		
correct:							accuracy of response: 1 = correct response; 0 = otherwise
latency: 							the response latency (in ms); measured from: onset of targets (adjectives)

facilitation_score:					only relevant for test if the response is correct and a usable meanRT-baseline of current target is available
								= the difference in reaction time of (meanRT-baseline of current target) - response time to current target							
									

(2) Summary data file: 'evaluativepriming_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)

ABpair1_stimuli- 
ABpair1_stimuli:					store the itemnumbers of the matched category A and category B stimuli for each item pair
								Example: AB pair1 Stimuli = "catA:3,catB:5" 
								=> itemnumber 3 of category A was matched with itemnumber 5 of category B
								
								
General Baseline and Test Performance (propCorrect & RT)								
								
propCorrect_baseline:				prop Correct baseline performance across all baseline trials
meanCorrRT_baseline:			mean response time (in ms) of correct categorizations across all baseline trials
propCorrect_baseline_positive:		prop Correct baseline performance across all positive target baseline trials
meanCorrRT_baseline_positive:		mean response time (in ms) of correct categorizations across all positive target baseline trials
propCorrect_baseline_negative:		prop Correct baseline performance across all negative target baseline trials
meanCorrRT_baseline_negative:	mean response time (in ms) of correct categorizations across all negative target baseline trials


propCorrect_test:					prop Correct test performance across all test trials
meanCorrRT_test:				mean response time (in ms) of correct categorizations across all test trials
propCorrect_test_positive:			prop Correct test performance across all positive target test trials
meanCorrRT_test_positive:			mean response time (in ms) of correct categorizations across all positive target test trials
propCorrect_test_negative:			prop Correct test performance across all negative target test trials
meanCorrRT_test_negative:		mean response time (in ms) of correct categorizations across all negative target test trials								
								
																
Baseline RT Performance Data per Stimuli:
								
meanRT_baseline_positive1- 
meanRT_baseline_positive12:		the mean response latency of categorizing positive targets mit indices 1-12 correctly

meanRT_baseline_negative1- 
meanRT_baseline_negative12:		the mean response latency of categorizing negative targets mit indices 1-12 correctly


Test RT Performance Data: only based on response latencies of correct responses

Facilitation: difference in response time to categorize targets during baseline compared to during the test.

Mean Facilitation Scores are response time measures in ms,
positive Scores: the categorization of targets was faster during the test (=> primes sped up the categorization)
negative Scores: the categorization of targets was slower during the test (=> primes slowed down the categorization)

DiffFacilitation Scores: is the difference in ms btw. the 
Mean Facilitation of positive adjectives and the Mean Facilitation of negative adjectives

meanFacilitation_catA_positive:		the mean facilitation (in ms) provided by category A (here: flowers) on categorizing positive adjectives
								compared to baseline performance
								
meanFacilitation_catA_negative:	the mean facilitation (in ms) provided by category A (here: flowers) on categorizing negative adjectives
								compared to baseline performance	
	
DiffFacilitation_catA:				the Facilitation Score for category A (here: flowers) across all category A stimuli	
(same for category B - here: insects)



Facilitation Scores for each individual prime: by actual stimulus index

meanFacilitation_catA_index1_positive: 	the mean facilitation (in ms) provided by image 1 of category A (here: flowers, "flower1.jpg") on categorizing positive adjectives
									compared to baseline performance
									
meanFacilitation_catA_index1_negative: 	the mean facilitation (in ms) provided by image 1 of category A (here: flowers, "flower1.jpg") on categorizing negative adjectives
									compared to baseline performance
									
DiffFacilitation_catA_index1:			the Facilitation Score for image 1 of category A (here: flowers, "flower1.jpg") 
(same for all category A and all category B stimuli)



Facilitation Scores for prime pairs: by paired primes

meanFacilitation_catA_pairAB1_positive: the mean facilitation (in ms) provided by category A (here: flowers) image of paired pair AB1 on categorizing positive 
									adjectives compared to baseline performance
									
meanFacilitation_catA_pairAB1-negative: the mean facilitation (in ms) provided by category A (here: flowers) image of paired pair AB1 on categorizing negative 
									adjectives compared to baseline performance
									
DiffFacilitation_catA_pairAB:			the Facilitation Score for cat A image of pair AB1
(same for all category A and all category B stimuli)

								

* 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 
___________________________________________________________________________________________________________________	

Prime Pairs:
At the start of the script, the script randomly pairs each of the categoryA primes with a categoryB prime.
The 12 positive (negative) targets are then randomly assigned to the 6 prime pairs:
each prime pair is assigned 2 positive targets and 2 negative targets
=> the paired primes are followed by the same targets throughout the test.
(same as is done for the category C and category D items; however these are treated as filler categories
and no summary data is calculated for these categories)

Baseline Practice: 12 practice trials (6 positive, 6 negative, order randomized) with performance feedback

Baseline: 2 blocks of 24 trials (number of blocks can be increased under Editable Parameters)
- 12 positive adjectives
- 12 negative adjectives
- order randomized

Test: 1 block of 96 trials

Target Trials:
- category A: 24 trials (12 positive, 12 negative: each category A stim is assigned 2 positive and 2 negative adjectives)
- category B: 24 trials  (12 positive, 12 negative: each category B stim is assigned 2 positive and 2 negative adjectives)
=> 2 stimuli of category A and category B are matched and precede the same two positive and the same two negative
adjectives

Filler Trials
- category C: 24 trials 
- category D: 24 trials
=> 2 stimuli of category C and category D are matched and precede the same two positive and the same two negative
adjectives


Trial Sequence:

-> Prime (or Fixation during Baseline) for 315ms
-> blank screen for 135ms
-> Target Adjective for 1750max or until response whichever comes first
-> ITI: 2500ms

___________________________________________________________________________________________________________________	
STIMULI
___________________________________________________________________________________________________________________	
provided by Millisecond Software - can be edited under section Editable Stimuli.

Templage Images:

12 positive adjectives/12 negative adjectives
6 images of flowers
6 images of insects
6 images of cars
6 images of appliances

___________________________________________________________________________________________________________________	
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:

Duration Parameters

/getReadyDuration:			the duration (in ms) of the get-ready trial (default: 5000ms)
/baselineITI:					the baseline intertrial interval (in ms) (default: 2500ms)
/testITI:						the test intertrial interval (in ms) (default: 2500ms)
/primeDuration :				the duration (in ms) of the primes (default: 315ms)
/primeTargetSOA :			the prime-target stimulus onset asynchrony (in ms) (default: 450ms)
/timeout_baseline:			the response timeout (in ms) during baseline trials (default: 1750ms)
/timeout_test:					the response timeout (in ms) during test trials (default: 1750ms)

/max_baseline:				the number of baseline blocks to run (default: 2)

/imageSize:					the proportional size of the images (default: 20%)
/targetSize:					the proportional size of the adjectives (default: 6%)


Response Key Assignments: 
Note: for this script to work properly the positive Key should be the left key and the
negative key should be the right key.
Tools -> Keyboard Scancodes

/posKey:						scancode of the  positive key (on the left) (default: 18 -> E)
/negKey:						scancode of the  negative key (on the right) (default: 23 -> I)