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*PSYCHOMOTOR VIGILANCE TEST*
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 06-07-2017
last updated: 08-20-2021 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 08-20-2021 Millisecond Software
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BACKGROUND INFO
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This script implements a Psychomotor Vigilance Test, a basic simple response time test.
The implemented procedure is based on:
Thomann, J.; R. Baumann, C.R.; Landolt, H.-P.; & Werth, E (2014).
Psychomotor Vigilance Task Demonstrates Impaired Vigilance in Disorders with Excessive Daytime Sleepiness.
Journal of Clinical Sleep Medicine, Vol. 10, 1019-1024.
Mathias Basner, MD, PhD, MSc, David F. Dinges, PhD, Maximizing Sensitivity of the Psychomotor Vigilance Test
(PVT) to Sleep Loss, Sleep, Volume 34, Issue 5, 1 May 2011, Pages 581–591, https://doi.org/10.1093/sleep/34.5.581
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TASK DESCRIPTION
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Participants are instructed to press the as fast as possible after a red stopwatch appears
on screen. A valid response (response occurs after stopwatch appears) is followed by reaction time
feedback. An invalid response (response occurs before stopwatch appears) is followed by a
brief error message.
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DURATION
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the default set-up of the script takes appr. 12 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: 'psychomotorvigilancetest_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.ISI: the currently randomly selected interstimulus interval in ms (randomly sampled from 2-10s)
response: the participant's response (scancode of response button): 57 = spacebar press
values.responseCategory: "false start" (= response before target occurs) vs.
"no lapse" (= valid response with latency <= 500ms)
vs. "lapse" (= valid response with latency > 500ms)
vs. "lapse-overrun" (= valid response with latency >= parameters.)
clock.target.stimulusonset: the onset time of the clock measured from onset of trial (in ms)
latency: the response latency (in ms); measured from onset of trial
values.rt: stores the latency of the response measured from onset of target stim
(calculated as the difference btw. latency - clock.target.stimulusonset)
values.countFalseStarts: counts the number of times an invalid (early) response is made in the current block
(2) Summary data file: 'psychomotorvigilancetest_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)
Summary Variables for Test Block only (excludes Habituation Phase): (see Thoman et al, 2014, p.1020)
expressions.meanRT: mean valid response latency (in ms; measured from onset of target)
expressions.reciprocalMeanRT: its reciprocal (see Thoman et al, 2014, p.1020)
expressions.medianRT: median valid response latency (in ms; measured from onset of target)
expressions.maxRT: the maximum valid response latency (in ms; measured from onset of target)
expressions.minRT: the minimum valid response latency (in ms; measured from onset of target)
expressions.meanRT500: mean valid response latency of responses with latencies <= 500ms (in ms; measured from onset of target)
expressions.reciprocalMeanRT500: its reciprocal (see Thoman et al, 2014, p.1020)
expressions.medianRT500: median valid response latency of responses with latencies <= 500ms (in ms; measured from onset of target)
expressions.maxRT500: the maximum valid response latency of responses with latencies <= 500ms (in ms; measured from onset of target)
expressions.minRT500: the minimum valid response latency of responses with latencies <= 500ms (in ms; measured from onset of target)
values.10thpercentile: in this script: the 10th percentile RT is taken as the value that sits at the 10%index (rounded to the nearest integer)
in the sorted RT list
Example: the sorted RT list (from slowest to fastest) contains 120 values;
the 10th percentile would be the value sitting at index 12 (120*10%) of this sorted list
values.90thpercentile: in this script: the 90th percentile RT is taken as the value that sits at the 90%index (rounded to the nearest integer)
in the sorted RT list
Example: the sorted RT list (from slowest to fastest) contains 120 values;
the 90th percentile would be the value sitting at index 108 (120*90%) of this sorted list
values.rangeRT: the difference in ms betw. 10th percentile RT and 90th percentile RT
values.10thpercentile500: in this script: the 10th percentile RT is taken as the value that sits at the 10%index (rounded to the nearest integer)
in the sorted RT list of valid latencies <= 500ms
values.90thpercentile500: in this script: the 90th percentile RT is taken as the value value that sits at the 90%index (rounded to the nearest integer)
in the sorted RT list of valid latencies <= 500ms
values.rangeRT500: the difference in ms btw. 10th percentile RT and 90th percentile RT of valid latencies <= 500ms
expressions.numberOfLapses: stores the total number of lapses (responses with latencies > 500ms) during the test block
expressions.transformedNumberOfLapses: numberOfLapses transformed with (sqrt(numberOfLapses) + sqrt(numberOfLapses+1)) (see Thoman et al, 2014, p.1020)
expressions.meanLapseRT: the average lapse in ms (average ms above 500ms for lapses)
expressions.cumulativeLapseRT: the sum of all lapse times during the test block
values.countFalseStarts: counts the number of false starts during the test block
expressions.falseRT: ratio of
'number of times participant responded BEFORE target appeared' to
'the number of times participant responded AFTER target appeared'
this ratio is presented as a percentage.
* separate data files: to change to one data file for all participants (on Inquisit Lab only), go to section
"DATA" and follow further instructions
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EXPERIMENTAL SET-UP
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1. Habituation Phase: ~1 min (Block is terminated after the last trial cycle within the designated timeframe)
- same task as actual test but performance is not used for summary statistics
Note: the Habituation Phase seamlessly turns into the Test Phase without giving participants any further warning.
During the first trial only, a reminder to press spacebar is presented on screen.
2. Test Phase: ~10 min (Block is terminated after the last trial cycle within the designated timeframe)
Trial Sequence:
ISI (randomly selected from 2-10s)-> target stim until response-> RT feedback (1000ms)
Note: If a response is made before the target stim appears, a short error message is flashed onto the screen
and a new trial is started.
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STIMULI
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target stimulus is a red stopwatch counter (counts in milliseconds)
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INSTRUCTIONS
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provided by Millisecond Software - 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: