Emotional Stroop Task with Keyboard Responses

Technical Manual

Last Modified: August 06, 2026 by K. Borchert (katjab@millisecond.com), Millisecond

Script Copyright © Millisecond Software, LLC

Background

This script implements an Aggression Themed Emotional 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 differences to color-meaning congruent and color-meaning incongruent combinations. The Aggression Stroop takes advantage of this basic Stroop interference effect by comparing reaction times to aggression related words, positive and negative words and neutral words: it is expected that words categories that grab a participant's attention significantly interfere with processing the color of the word and slow down response times.

The implemented procedure is based on Smith & Waterman (2003) and uses keyboard input instead of voice recordings.

References

Smith, P. & Waterman, M. (2003). Processing bias for aggression words in forensic and nonforensic samples. Cognition and Emotion, 17, 681-701.

Lisas Scores:
Vandierendonck A. On the Utility of Integrated Speed-Accuracy Measures when Speed-Accuracy Trade-off is Present. J Cogn. 2021 Mar 18;4(1):22. doi: 10.5334/joc.154. Erratum in: J Cogn. 2021 Nov 10;4(1):59. doi: 10.5334/joc.192. PMID: 33778368; PMCID: PMC7977027.

Duration

5 minutes

Description

Participants are presented words from 5 different categories (aggression, neutral, positive, negative, color word) 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.

Procedure

1. Practice Block: 10 trials (not original; this script uses the words "one" to "ten" as practice stimuli)
2. Test Block: 125 trials (= 5 categories x 25 trials); trials are randomly sampled
without replacement
• error feedback given; to remove follow instructions under section TRIALS

Stimuli

• original stimuli by Smith & Waterman (2003)
(due to a potential typo in the original article one word appeared
under two categories (Appendix2); we replaced it with a word that is similar in length and appearance
=> section Editable STIMULI-> Negative Words)

• each color appears 6 times in each category (the 7th pairing of word-color is random)
• color words "red", "yellow", "blue" and "green" are not used as targets
• 5 color words are repeats (see Smith & Waterman, 2003)

Instructions

Instructions are not original to the task. They are provided by Millisecond
and can be edited in script "emotionalstroopwithkeyboardinput_instructions_inc.iqjs"

Scoring

Linear Integrated Speed-Accuracy Scores (Lisas): (Vandierendonck, 2021)
A LISAS score is simply the weighted sums of the RT and PE measures, with weights being calculated as the ratio of
the (correct) response time standard deviation to the error rate standard deviation.
LISAS output is expressed in units of time. It represents an individual's "error-corrected processing speed".

LISAS = meanRT(of correct responses) + (sdRT/sdErrors) * propErrors

=> A low LISAS means the participant was both fast and accurate; the minimum LISAS that can be assigned to a participants
equals their mean correct response time (this happens with error rates = 0);
=> A high LISAS means the participant struggled with accuracy or had to drastically slow down to maintain accuracy

in this script sdRT and sdErrors are based on the pooled standard deviation of all test trials

Summary Data

File Name: emotionalstroopwithkeytboardinput_summary*.iqdat

Data Fields

NameDescription
startDate Date the session was run
startTime Time the session was run
subjectId Participant ID
groupId Group number
sessionId Session number
elapsedTime Session duration in ms
inquisit.version Inquisit version number
computer.platform Device platform: win | mac |ios | android
computer.touch 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities
computer.hasKeyboard 0 = no external keyboard detected; 1 = external keyboard detected
completed 0 = Test was not completed
1 = Test was completed
Summary Performance Metrics (Test Only)
errorRate Overall error rate
errorRateNeu Error rate for Neutral words (Baseline)
errorRateAgg Error rate for Aggression words
errorRateNeg Error rate for Negative words
errorRatePos Error rate for Positive words
errorRateCol Error rate for Color words
meanRT Overall mean response time of correct responses (in ms)
meanRTNeu Mean correct response time to Neutral words (in ms) (Baseline)
meanRTAgg Mean correct response time to Aggression words (in ms)
meanRTNeg Mean correct response time to Negative words (in ms)
meanRTPos Mean correct response time to Positive words (in ms)
meanRTCol Mean correct response time to Color words (in ms)
Speed-Accuracy Trade Off: Linear Integrated Speed-Accuracy Score, Lisas ("Error-Corrected Processing Speed")
sdRTPooled The pooled standard deviation of correct response times across all test trials
errorSDPooled The pooled standard deviation of error rates across all test trials
lisasNeu LISAS score for Neutral trials (Baseline)
lisasAgg LISAS score for Aggression trials
lisasNeg LISAS score for Negative trials
lisasPos LISAS score for Positive trials
lisasCol LISAS score for Color trials
Error-Based Bias Scores
biasErrorAgg Difference in error rates (errorRatesAgg - errorRatesNeu)
=> positive scores: meaning of aggression words interfered more than meaning of neutral words on color categorization task
based on error rates
biasErrorNeg Difference in error rates (errorRatesNeg - errorRatesNeu)
biasErrorPos Difference in error rates (errorRatesPos - errorRatesNeu)
biasErrorCol Difference in error rates (errorRatesCol - errorRatesNeu)
Responsetime-Based Bias Scores
biasRTAgg Bias Score based on response times: Difference in mean correct response times (meanRTAgg - meanRTNeu)
=> positive scores: meaning of aggression words interfered more than meaning of neutral words on color categorization task
based on response times
biasRTNeg Difference in mean correct response times (meanRTNeg - meanRTNeu)
biasRTPos Difference in mean correct response times (meanRTPos - meanRTNeu)
biasRTCol Difference in mean correct response times (meanRTCol - meanRTNeu)
Lisas-Based Bias Scores
biasLisasAgg Bias Score based on LISAS: Difference in LISAS scores ("error-corrected processing speed") from Aggression and Neutral Trials (lisasAgg - lisasNeu)
=> positive difference, "error-corrected processing speed" was faster for neutral than for Aggression ones
=> a positive difference supports that processing Aggression trials required more cognitive effort, time, or
accuracy sacrifices than processing neutral trials
biasLisasNeg Difference in LISAS scores ("error-corrected processing speed") from Negative and Neutral Trials (lisasNeg - lisasNeu)
biasLisasPos Difference in LISAS scores ("error-corrected processing speed") from Positive and Neutral Trials (lisasPos - lisasNeu)
biasLisasCol Difference in LISAS scores ("error-corrected processing speed") from Negative and Neutral Trials (lisasCol - lisasNeu)

Raw Data

File Name: emotionalstroopwithkeytboardinput_raw*.iqdat

Data Fields

NameDescription
date Date the session was run
time Time the session was run
subject Participant ID
group Group number
session Session number
build Inquisit version number
computer.platform Device platform: win | mac |ios | android
computer.touch 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities
computer.hasKeyboard 0 = no external keyboard detected; 1 = external keyboard detected
blockcode The name the current block (built-in Inquisit variable)
blocknum The number of the current block (built-in Inquisit variable)
trialcode The name of the currently recorded trial (built-in Inquisit variable)
trialnum The number of the currently recorded trial (built-in Inquisit variable)
trialnum is a built-in Inquisit variable; it counts all trials run
even those that do not store data to the data file.
condition Practice,neutral,aggression,negative,positive,color
target The currently selected target word
color The currently selected color
response The participant's key response (scancode of response button)
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)
responseText The label of the pressed response button
responseCategory The interpreted key response
"red"
"green"
"blue"
"yellow"
correct The correctness of the response (1 = correct; 0 = incorrect)
latency The response latency (in ms); measured from onset of word

Parameters

The procedure can be adjusted by setting the following parameters.

NameDescriptionDefault
Timing Parameters
fixationCrossPresentationTime Time (in ms) that fixation cross is presented500
Response Keys
keyRed The red response button"D"
keyGreen The green response button"F"
keyBlue The blue response button"J"
keyYellow The yellow response button"K"