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Lexical Decision Task
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last updated: 03-10-2020 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 03-10-2020 Millisecond Software
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BACKGROUND INFO
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This script implements a simple Lexical Decision Task to investigate semantic memory and lexical access.
The implemented procedure is based on:
Lepore & Brown (2002), The Role of Awareness: Divergent Automatic Stereotype
Activation and Implicit Judgment Correction, Social Cognition, 20 (4), pp 321-351.
This script uses placeholders for actual stimuli.
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TASK DESCRIPTION
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Participants are asked to categorize words into words and nonwords by pressing the E-key (non words)
or I-key (words) as fast as possible when a word/nonword stimulus appears on screen.
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DURATION
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the default set-up of the script takes appr. 3 minutes to complete
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DATA FILE INFORMATION
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The default data stored in the data files are:
(1) Raw data file: 'lexicaldecisiontask_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 such as feedback trials. Thus, trialnum
may not reflect the number of main trials run per block.
values.condition: "Category Word", "Neutral Word", "Non Word"
values.presentedStim: the currently presented word or non-word
response: the participant's response (scancode of response button)
18 = E (non word)
23 = I (word)
57 = spacebar
correct: the correctness of the response (1 = correct; 0 = incorrect)
latency: the response latency (in ms); latency measured from onset of stimulus
(2) Summary data file: 'lexicaldecisiontask_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)
expressions.PropCorrect: overall proportion correct across all testtrials
expressions.MeanRT: overall mean latency of correct responses across all correct testtrials
expressions.STD: overall standard deviation of correct latencies
expressions.MedianRT: overall median latency of correct responses across all correct testtrials
expressions.PropCorrect_CatW: proportion correct of responses to category words
expressions.MeanRT_CatW: mean latency of correct responses to category words
expressions.STD_CatW: standard deviation of correct responses to category words
expressions.MedianRT_CatW: median latency of correct responses to category words
expressions.PropCorrect_NeutralW proportion correct of responses to neutral words
expressions.MeanRT_NeutralW: mean latency of correct responses to neutral words
expressions.STD_NeutralW: standard deviation of correct responses to neutral words
expressions.MedianRT_NeutralW: median latency of correct responses to neutral words
expressions.PropCorrect_NonW: proportion correct of responses to non words
expressions.MeanRT_NonW: mean latency of correct responses to non words
expressions.STD_NonW: standard deviation of correct responses to non words
expressions.MedianRT_NonW: median latency of correct responses to non words
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EXPERIMENTAL SET-UP
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3 types of words (category words, neutral words, nonwords) tested within participants in a mixed design
1 Practice Block: 6 trials (3 neutral words, 3 nonwords; order randomly selected)
1 Test Block: 52 trials (13 category words, 13 neutral words, 26 non words; order and stimuli randomly selected)
Trial Sequence:
* (for 700ms) -> stimulus (250ms) -> blank screen until response (latency measured from onset of stimulus)
(Durations can be edited under section Editable Parameters)
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STIMULI
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are spaceholders - actual stimuli can be easily inserted under section Editable Stimuli
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INSTRUCTIONS
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can be edited under section Editable 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:
/fixationDuration: the duration (in ms) of the fixation stimulus presented at the start of each trial (default: 700ms)
/stimDuration: the duration (in ms) of the presented word/nonword in ms (default: 250ms)
/stimSize: the proportional height (to active canvas) of the stimuli (default: 5%)