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Fruit Stroop
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 07-02-2024
last updated: 01-06-2025 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 01-06-2025 Millisecond Software
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BACKGROUND INFO
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This script implements Millisecond Software's version of the Fruit Stroop (Okuzumi et al, 2015),
a test to investigate selective attention and response inhibition.
This script uses 4 fruits/vegetables (4 colors) instead of three.
Reference:
Okuzumi, H., Ikeda, Y., Otsuka, N., Saito, R., Oi, Y., Hirata, S., Haishi, K., & Kokubun, M. (2015).
Stroop-Like Interference in the Fruit Stroop Test in Typical Development.
Psychology (Irvine, Calif.), 6(5), 643–649. https://doi.org/10.4236/psych.2015.65062
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TASK DESCRIPTION
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Participants are given images of fruits and vegetables in either their canonical colors
(aka 'universally agreed'/'expected') colors (= congruent), e.g. a red strawberry, or in
colors that contradict their canonical colors (= incongruent), e.g. a blue strawberry.
In canonical color tasks, participants are asked to press a response button indicating the
canonical color of the fruit/vegetable.
In surface color tasks, participants are asked to press a response button indicating
the surface color of the fruit/vegetable.
This script collects responses and response times for INITIAL responses (first responses),
but allows participants to correct responses until a 'continue' button (a black arrow icon)
is pressed.
The script runs different phases (see section Editable Parameters to customize)
- Baseline: color categorization of squares (here: red, green, blue, yellow).
- Congruent: color categorization of fruits/vegetables in their canonical colors (here: strawberry, salad, plum, banana)
- Neutral: canonical color categorization of black and white fruits/vegetables (here: strawberry, salad, plum, banana)
- Incongruent: canonical color categorization of fruits/vegetables presented in non-canonical colors
(here: strawberry, salad, plum, banana)
- Mixed: canonical color categorization of fruits/vegetables presented in non-canonical colors OR canonical colors
- MixedSurface*: surface color categorization of fruits/vegetables presented in non-canonical colors OR canonical colors
* this phase is not part of the default sequence but can be run by this script
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DURATION
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the default set-up of the script takes appr. 5 minutes to complete
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DATA OUTPUT DICTIONARY
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The fields in the data files are:
(1) Raw data file: 'fruitstroop_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: with the current subject id
group: with the current group id
session: 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.
!Trialcode 'responseRecording' stores the important trial data for each phase
phase: "Baseline", "Congruent", "Control", "Incongruent", "MixedPractice", "Mixed"
trialCounterPerPhase: trackes the number of trials in each phase
colorFocus: "canonical" (aka 'universally agreed') vs "surface" (the actual printed color)
image: the presented target image
congruence: 0 = incongruent; 1 = congruent; 3 = neutral (black/white images)
attempts: tracks the number of times participants presses a different response button
for a given target image
//accuracy evaluation:
corrResp: stores the correct response (button) for a given target (and colorFocus)
"color1" (here: red -> depends on settings under section Editable Parameters)
"color2" (here: green)
"color3" (here: blue)
"color4" (here: yellow)
response: the response button pressed by participant ("color1", "color2", "color3", "color4")
correct: correctness of response (1 = correct, 0 = error) for the given response (built-in variable)
initialResp: the first response button pressed
initialAcc: the correctness of the first response button pressed for a given target
finalResp: the final response button pressed
finalAcc: the correctness of the final response button pressed for a given target
latency: built-in latency variable (in ms) for each data-recording trial
initialRT: the response time (in ms) of the first response; measured from target onset until first response button is pressed
finalRT: the response time (in ms) at the end of a trial; measured from target onset until continue-symbol is pressed
initialRespChange: 1 = the initial response for a target was changed at some point during the trial;
0 = the initial response was submitted
(Notes:
- if a participant changes the initial response but then changes it back to the same value at a later point,
this variable would still store '1'
- if a participant presses the same response button multiple times, the script
considers this the same response)
//additional counts:
countConsecCon: counts the number of consecutive Congruent trials in the current block
countConsecInc: counts the number of consecutive Incongruent trials in the current block
(2) Summary data file: 'fruitstroop_summary*.iqdat' (a separate file for each participant)
inquisit.version: Inquisit version run
computer.platform: the platform the script was run on (win/mac/ios/android)
startdate: date script was run
startTime: time script was started
subjectId: assigned subject id number
groupId: assigned group id number
sessionId: assigned session id number
elapsedTime: time it took to run script (in ms); measured from onset to offset of script
completed: 0 = script was not completed (prematurely aborted);
1 = script was completed (all conditions run)
////BASELINE
durationBaseline: the duration (in ms) of the Baseline Task (measured from onset of fixation cross until task is done)
trialCountBaseline: the number of Baseline trials run
propResponseChangesBaseline: proportion of Baseline trials in which participant changed their response at least once
////////initial response:
propCorrectInitialBaseline: proportion correct FIRST response
meanRTInitialBaseline: mean response time (in ms) of FIRST responses (regardless of accuracy), measured from onset of target until first response button is pressed
meanCorrRTInitialBaseline: mean response time (in ms) of CORRECT FIRST responses
////////final response:
propCorrectFinalBaseline: proportion correct correct FINAL response
meanRTFinalBaseline: mean response time (in ms) of FINAL response (regardless of accuray),
measured from onset of target until continue button is pressed
meanCorrRTFinalBaseline: mean response time (in ms) of CORRECT FINAL responses
(same for all remaining phases)
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EXPERIMENTAL SET-UP
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This section describes the experimental setup of the default settings of the script.
Check section Editable Parameters to change:
- the phases (Baseline, Congruent, Control, Incongruent, Mixed) you want to run
- the number of trials in each phase
(1) General Instructions
(2) Baseline Phase: 12 trials (see section Editable Parameters)
The Baseline phase presents red, green, blue and yellow squares. The squares do not have
any canonical ('inherent'/'universally agreed') colors.
Participants are asked to press one of four colored response buttons (red, green, blue, yellow)
to indicate the color of the square. Participants can correct response until the continue button
(black arrow) is pressed.
The order of the squares is randomized and each color is presented equally often.
The script notes participants' responses (first and final),
response times and accuracy of their responses.
(3) Congruent Phase: 12 trials (see section Editable Parameters)
The Congruent Phase presents 4 fruits/vegetables (strawberry, salad, plum, banana)
in their canonical ('inherent'/'universally agreed') colors. The items are
said to be 'congruent' because their canonical colors and surface colors are the same.
Participants are asked to press one of four colored response buttons (red, green, blue, yellow)
to indicate the color of the fruits/vegetables. Participants can correct response until
the continue button (black arrow) is pressed.
The order of the fruits/vegetables is randomized and each fruit/vegetable is presented equally often.
The script notes participants' responses (first and final),
response times and accuracy of their responses.
(4) Neutral Phase: 12 trials (see section Editable Parameters)
The Neutral Phase presents the same 4 fruits/vegetables as black and white images (no surface colors).
Participants are asked to press one of four colored response buttons (red, green, blue, yellow)
to indicate the color that the fruits/vegetables should have (= canonical colors).
Participants can correct response until the continue button (black arrow) is pressed.
The order of the fruits/vegetables is randomized and each fruit/vegetable is presented equally often.
The script otes participants' responses (first and final),
response times and accuracy of their responses.
(5) Incongruent Phase: 12 trials (see section Editable Parameters)
The Incongruent Phase presents the same 4 fruits/vegetables in surface colors that
are incongruent with their canonical ('inherent'/'universally agreed') colors.
For example, participants may see a red salad.
Participants are asked to press one of four colored response buttons (red, green, blue, yellow)
to indicate the color that the fruits/vegetables should have (= canonical colors).
Participants can correct response until the continue button (black arrow) is pressed.
The order of the fruits/vegetables is randomized and each fruit/vegetable is presented equally often.
The script notes participants' responses (first and final),
response times and accuracy of their responses.
(6) Mixed Phase:
The Mixed Phase presents a sequence of Congruent and Incongruent trials (images of fruits/vegetables
in their canonical colors or unexpected colors, respectively).
Participants are asked to press one of four colored response buttons (red, green, blue, yellow)
to indicate the color that the fruits/vegetables should have. Participants can correct response until
the continue button (black arrow) is pressed.
The Mixed Phase runs a practice session before the test session:
(a) Practice: 12 trials
Half the practice trials are Congruent trials, the other half are incongruent trials.
The order of Congruent and Incongruent trials can be specified via editable lists
(list.congruenceMixedPractice/list.congruenceMixed).
The default order is randomized. Colors and images of fruits and vegetable may be unbalanced in this
phase depending on the number of trials that are run.
Participants receive error feedback during the practice trials.
(b) Test: 36 trials (12 incongruent trials, 24 congruent trials), see section Editable Parameters
Incongruent Trials: each of the 12 possible images is run once
Congruent Trials: each of the 4 possible images is run 6 times
=> the number of surface colors presented as well as the type of fruits/vegetables is balanced.
The order of Congruent and Incongruent trials can be specified via editable lists
(list.congruenceMixedPractice/list.congruenceMixed).
The default setup runs a randomized order.
(7) Mixed Phase - Surface (colors) (*NOT RUN BY THE DEFAULT SEQUENCE*)
The surface color Mixed Phase runs a mixed phase of congruent and incongruent (canonical) colored
fruits and vegetables but participants are asked to indicate the SURFACE color of the
items. In any other ways the procedure is the same as for the canonical color focused Mixed Phase.
Trial Sequence:
-> ITI (fixation cross in the center) for 250ms (editable parameter)
-> target presentation with response buttons.
Once one response button is pressed, the continue button (black arrow)
appears. Participant can correct responses until the black arrow is pressed.
-> (feedback for mixed practice trials)
-> response Recording Trial: records one data line per trial ('summary of the trial')
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STIMULI
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provided by Millisecond Software - can be edited under section 'Editable Stimuli'
Based on material shared by A.C. Schneider
Note: the objects (fruits and vegetables) used by this script are
culture/country specific (e.g. strawberry).
You can easily use different objects and colors by following these steps:
- change objects (and colors) under section Editable Parameters
- change filenames under section Editable Stimuli (Note: filenames should contain the object
names as spelled under section Editable Parameters)
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INSTRUCTIONS
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provided by Millisecond Software - can be edited under section 'Editable Instructions'
Note: if you change the individual tasks to run, you may need to edit the 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:
////////////////////EXP DESIGN ELEMENTS:
/ runBaseline = true //true = Baseline is run; false = Baseline is skipped
/ runCongruent = true //true = Congruent Phase is run; false = Congruent Phase is skipped
/ runNeutral = true //true = Neutral Phase is run; false = Neutral Phase is skipped
/ runIncongruent = true //true = Incongruent Phase is run; false = Incongruent Phase is skipped
/ runMixed = true //true = Mixed (Canonical) Phase is run; false = Mixed (Canonical) Phase is skipped
//Note: if settings are changed, instructions may have to be slightly altered
/ runMixedSurface = false //true = Mixed Surface(color) Phase is run; false = Mixed Surface(color) Phase is skipped
/////////////////////TrialNumbers in the different phases
/ numberOfBaselineTrials = 12 //if divisible by 4: all 4 images are repeated equally often
/ numberOfCongruentTrials = 12 //if divisible by 4: all 4 images are repeated equally often
/ numberOfNeutralTrials = 12 //if divisible by 4: all 4 images are repeated equally often
/ numberOfIncongruentTrials = 12 //if divisible by 12: all 12 images are repeated equally often
///MIXED BLOCK: applies to both mixed(canonical) and mixed(surface) phases
//IMPORTANT: the order of congruent and incongruent items in the different Mixed phases
//can be further controlled
//via lists list.congruenceMixedPractice/list.congruenceMixed (see below)
/ numberOfMixedPracticeTrials = 12 //number of practice trials in the Mixed condition
/ numberOfCongruentMixedTrials = 24 //number of Congruent trials in the Mixed test block;
//if divisible by 4: all 4 images are repeated equally often
/ numberOfIncongruentMixedTrials = 12 //number of Incongruent trials in the Mixed test block;
//if divisible by 12: all 12 images are repeated equally often
////////////////////STIMULI PARAMETERS:
//Canonical Colors used in this script: in case different canonical colors are used,
//change the settings here (Note: keep English spelling of color names, as the script
//will use these color words to color the respective response buttons)
/ color1 = "red"
/ color2 = "green"
/ color3 = "blue"
/ color4 = "yellow"
//Fruits and Vegetables and their respective canonical colors used by the script.
//In case different objects should be used, change the settings here and change filenames
//accordingly (using the same object names):
/ object1 = "strawberry"
/ object1CanonicalColor = parameters.color1
/ object2 = "salad"
/ object2CanonicalColor = parameters.color2
/ object3 = "plum"
/ object3CanonicalColor = parameters.color3
/ object4 = "banana"
/ object4CanonicalColor = parameters.color4
// sizing parameters
/ targetHeightPct = 20% //proportional height of the target images (proportional to canvasHeight of screen)
////////////////////TIMING PARAMETERS
/ testStartDelayMS = 500 //the delay (in ms) of the first trial.iti in each test block (Note: the first trial.iti in each block will effectively run 500ms longer)
/ itiDurationMS = 250 //the duration (in ms) of trial.iti (presentation of fixation cross)
as well as list-elements that set the ratio of Congruent:Incongruent trials for the Mixed phase.
