Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: July 02, 2024
Last Modified: August 06, 2026 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements Millisecond'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.
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
5 minutes
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
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')
provided by Millisecond - can be edited under section 'Editable Stimuli'
Based on material shared by A.C. Schneider
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 ( filenames should contain the object
names as spelled under section Editable Parameters)
provided by Millisecond - can be edited under section 'Editable Instructions'
in script 'fruitstroop_instructions_inc.iqjs'
if you change the individual tasks to run, you may need to edit the instructions
File Name: fruitstroop_summary*.iqdat
| Name | Description |
|---|---|
| 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 |
Performance Performance Metrics By Phase (Explained For 'Baseline' Phase Only): Baseline, Congruent, Neutral, Incongruent, Mixed (Mixedcon=Mixedcongruent, Mixedinc=Mixedincongruent) |
|
| 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 in Baseline phase |
| 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 in Baseline phase |
Final Response |
|
| propCorrectFinalBaseline | Proportion correct correct FINAL response in Baseline phase |
| meanRTFinalBaseline | Mean response time (in ms) of FINAL response (regardless of accuray) in Baseline phase, measured from onset of target until continue button is pressed |
| meanCorrRTFinalBaseline | Mean response time (in ms) of CORRECT FINAL responses in Baseline phase |
File Name: fruitstroop_raw*.iqdat
| Name | Description |
|---|---|
| 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) trialcode 'responseRecording' stores the important trial data for each phase |
| 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. |
| 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 |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Design |
||
| runBaseline | True = Baseline is run; false = Baseline is skipped | true |
| runCongruent | True = Congruent Phase is run; false = Congruent Phase is skipped | true |
| runNeutral | True = Neutral Phase is run; false = Neutral Phase is skipped | true |
| runIncongruent | True = Incongruent Phase is run; false = Incongruent Phase is skipped | true |
| runMixed | True = Mixed (Canonical) Phase is run; false = Mixed (Canonical) Phase is skipped | true |
| runMixedSurface | True = Mixed Surface(color) Phase is run; false = Mixed Surface(color) Phase is skipped if settings are changed, instructions may have to be slightly altered | false |
| numberOfBaselineTrials | Number of Baseline Trials; if divisible by 4: all 4 images are repeated equally often | 12 |
| numberOfCongruentTrials | Number of Congruent Trials; if divisible by 4: all 4 images are repeated equally often | 12 |
| numberOfNeutralTrials | Number of Neutral Trials; if divisible by 4: all 4 images are repeated equally often | 12 |
| numberOfIncongruentTrials | Number of Incongruent Trials; if divisible by 12: all 12 images are repeated equally often | 12 |
| numberOfMixedPracticeTrials | Number of practice trials in the Mixed condition - applies to both mixed(canonical) and mixed(surface) phases | 12 |
| numberOfCongruentMixedTrials | Number of Congruent trials in the Mixed test block - applies to both mixed(canonical) and mixed(surface) phases if divisible by 4: all 4 images are repeated equally often | 24 |
| numberOfIncongruentMixedTrials | Number of Incongruent trials in the Mixed test block - applies to both mixed(canonical) and mixed(surface) phases if divisible by 12: all 12 images are repeated equally often | 12 |
Colors: Keep English Spelling |
||
| color1 | "red" | |
| color2 | "green" | |
| color3 | "blue" | |
| color4 | "yellow" | |
Fruits And Vegetables And Their Respective Canonical Colors Used By The Script. |
||
| object1 | "strawberry" | |
| object1CanonicalColor | parameters.color1 | |
| object2 | "salad" | |
| object2CanonicalColor | parameters.color2 | |
| object3 | "plum" | |
| object3CanonicalColor | parameters.color3 | |
| object4 | "banana" | |
| object4CanonicalColor | parameters.color4 | |
Sizing Parameters |
||
| targetHeightPct | Proportional height of the target images (proportional to canvasHeight of screen) | 20% |
Timing Parameters |
||
| testStartDelayMS | The delay (in ms) of the first trial.iti in each test block ( the first trial.iti in each block will effectively run 500ms longer) | 500 |
| itiDurationMS | The duration (in ms) of trial.iti (presentation of fixation cross) | 250 |