German Version
German translation provided by K. Borchert for Millisecond Software
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Leuven Embedded Figures Test (L-EFT)
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 06-23-2025
last updated: 06-24-2025 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 06-24-2025 Millisecond Software
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BACKGROUND INFO
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This script implements the Leuven Embedded Figures Test (L-EFT).
The L-EFT is a percepetual match-to-sample test. It measures how fast participants
can identify an embedded figure within a more complex pattern.
The test manipulates several variables (such as shape symmetry and number of lines)
to investigate the impact of target features on detectability
//////Reference:
de-Wit, L., Huygelier, H., Van der Hallen, R., Chamberlain, R. & Wagemans, J. (2017).
Developing the Leuven Embedded Figures Test (L-EFT): testing the stimulus features that influence embedding.
PeerJ 5:e2862;
DOI 10.7717/peerj.2862
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TASK DESCRIPTION
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Participants view several individual target shapes and select amongst three complex patterns the one
that contains ('embeds') the target shape (Note: the target shape is the same in size and rotation).
The script contains functionality to allow for error correction before moving on to the next shape
(this error correction can be turned on via Editable Parameter settings).
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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 DICTIONAIRY
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The fields in the data files are:
(1) Raw data file: 'XXX_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.
////parameter setting:
errorCorrectionProcedure true: error feedback is given and needs to be corrected before next trial can start
false: no error feedback is provided; next trial starts despite errors
trialCounter: tracks the number of trials run
index: the selected target index (0-63)
targetLines: the number of lines of the current target
targetShape: "closed" vs. "open" shape of the current target
targetSymmetry: "sym" vs. "asym" of the current target
solutionComplexity: complexity level of the current solution (1-4; with 1 being the least complex embedded shape)
targetImage: presented target image
solutionAImage: solutionA image (correct)
solutionBImage: solutionB image (foil)
solutionCImage: solutionC image (foil)
solutionAX: percentage horizontal screen position of solutionA
solutionBX: percentage horizontal screen position of solutionA
solutionCX: percentage horizontal screen position of solutionA
(Note: 25%=left; 50%=center; 75%=right)
response: the response of participant (selected solution)
selectedSolution: the currently selected solution
correct: correctness of current selection (1 = correct, 0 = error)
Note: trial.lEftSummary stores the accuracy of the final submitted response
latency: response latency (in ms); measured from: onset of trial
errorCounter: number of times participants submitted an incorrect selection during a trial
acc: stores the accuracy of the current selection
initialAcc: stores the accuracy of the FIRST submitted response
finalAcc: stores the accuracy of the FINAL submitted response
rt: cumulative response time (in ms) until the final submit button is pressed
initialRT: cumulative response time (in ms) for FIRST submitted response
finalRT: cumulate response time (in ms) for FINAL submitted response
(2) Summary data file: 'xxx_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)
////parameter setting:
errorCorrectionProcedure true: error feedback is given and needs to be corrected before next trial can start
false: no error feedback is provided; next trial starts despite errors
//summary data:
initialPropCorrect: proportion correct FIRST solution submissions
initialCorrMeanRT: mean response times (in ms) of FIRST submitted solutions that were correct
finalCorrMeanRT: mean response times (in ms) of FINAL submitted solutions that were correct
(Note: only relevant if participants needed to correct error responses)
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EXPERIMENTAL SET-UP
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Design: all factors tested within
4 (number of lines) x 2 (shape types: open vs. closed) x 2 (symmetry levels: sym vs. asym) = 16 shapes
16 shapes x 4 (solution complexity: 1-4) = 64 trials total
- order of the 64 trials is randomly determined
- horizontal screen position (left, center, right) of the 3 provided solutions is determined randomly for each trial
- intertrial interval is 500 by default (can easily be changed via parameter settings)
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//Error Correction Procedure
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This script provides the functionality (via parameter settings) to select whether errors should be
corrected before a participant can move on to the next trial (see setting for parameters.errorCorrectionProcedure)
if parameters.errorCorrectionProcedure is set to 'true':
- participants have to select the correct response before they can move on to the next trial
=> if a wrong solution is selected, it is highlighted with a red frame for 1s and participant needs to change
their selection. In addition, a text stimulus 'try again!' is presented on screen.
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STIMULI
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The original stimuli are publicly available at:
target shapes: https://dx.doi.org/10.6084/m9.figshare.3807885
solutions: https://dx.doi.org/10.6084/m9.figshare.3807894
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INSTRUCTIONS
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instructions are modelled after the ones used for the demo at:
https://psytests.be/clinicians/test-centrum/l-eft.php
They can be edited in script "l_eft_instructions_inc.iqjs"
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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:
//design:
/ errorCorrectionProcedure = false //true: error feedback is given and needs to be corrected before next trial can start
//false: no error feedback is provided; next trial starts despite errors
//timing parameters
/ itiMS = 500 //duration (in ms) of intertrial interval (blank screen in between trials)
/ errorFeedbackMS = 1000 //duration (in ms) that error feedback is presented (if errorCorrectionProcedure = true)
