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INSPECTION TIME TASK
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 12-05-2014
last updated: 02-04-2025 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 02-04-2025 Millisecond Software
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BACKGROUND INFO
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This script runs an Inspection Time task; a task used to study the early stages of visual processing.
The implemented task is based on:
Deary, I.J., Enrico Simonotto, E., Meyer, M., Marshall, A., Ian Marshall, I., Goddard, N. & Wardlawf, J.M. (2004).
The functional anatomy of inspection time: an event-related fMRI study. NeuroImage, 22, 1466– 1479.
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TASK DESCRIPTION
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Participants see stimuli that have one long and one short arm. The stimuli are presented for variable
durations before they are covered by a mask. Participants have to decide whether the long arm
was left or right and press corresponding response keys.
Participants are told that reaction time is unimportant.
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DURATION
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the default set-up of the script takes appr. 18 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: 'inspectiontimetask_raw*.iqdat'
build: The specific Inquisit version used (the 'build') that was run
computer.platform: the platform the script was run on (win/mac/ios/android)
display.refreshRate: the vertical refresh rate of the current monitor
NOTE: Deary et al (2004) used the following durations: 6, 12, 19, 25, 31, 37, 44, 50, 62, 75, 87, 100, 125, 150, 200 ms
on a monitor with a vertical refresh rate = 160Hz
!!! Most monitors have a vertical refresh rate of 60Hz and therefore it won't be possible
to present any stimuli at 6 or 12 ms. One these computers it takes about 17ms (minimum)
to refresh the screen (thus 17ms is the minimum that can be used on 60Hz monitors).
date, time: date and time script was run
subject, group, with the current subject/groupnumber
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 such as feedback trials
countTrials: counts all stim trials
stimDuration: duration (in ms) of current stim
stimduration_condition1-15 (depending on stimduration)
location: 1 = right long arm; 2 = left long arm
stimulusItem: the presented stimuli in order of trial presentation
response: the participant's response (scancode of response buttons)
30 = A
38 = L
correct: accuracy of response: 1 = correct response; 0 = otherwise
latency: the response latency (in ms); measured from: onset of stims
(2) Summary data file: 'inspectiontimetask_summary*.iqdat'
inquisit.version: Inquisit version run
computer.platform: the platform the script was run on (win/mac/ios/android)
display.refreshRate: the vertical refresh rate of the current monitor
NOTE: Deary et al (2004) used the following durations: 6, 12, 19, 25, 31, 37, 44, 50, 62, 75, 87, 100, 125, 150, 200 ms
on a monitor with a vertical refresh rate = 160Hz
!!! Most monitors have a vertical refresh rate of 60Hz and therefore it won't be possible
to present any stimuli at 6 or 12 ms. One these computers it takes about 17ms (minimum)
to refresh the screen (thus 17ms is the minimum that can be used on 60Hz monitors).
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)
propcorrectStim1: proportion correct responses for stim duration 1 (here: 6ms)
(the same for all 15 stim durations)
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EXPERIMENTAL SET-UP
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(1) 15 stimulus presentation durations tested with 20 repetitions (default).
Deary et al (2004) used the following durations: 6, 12, 19, 25, 31, 37, 44, 50, 62, 75, 87, 100, 125, 150, 200 ms
on a monitor with a vertical refresh rate = 160Hz
!!! Most monitors have a vertical refresh rate of 60Hz and therefore it won't be possible
to present any stimuli at 6 or 12 ms. One these computers it takes about 17ms (minimum) to refresh the screen.
(set durations under section EDITABLE CODE -> Editable Values)
(2) The stimuli duration times are selected randomly without replacement (method of constant stimuli).
(3) The long arm is located on the left for 50% of the trials
(4) Practice block for 25 randomly durations (number of trials can be edited)
Trial Sequence:
(1) Cue ('+') for 500ms (editable)
(2) Interstimulus interval: Blank screen for 600ms (editable)
(3) Stimulus for variable duration
(4) Mask for 500ms (editable)
(5) Trial continues until response is made
(6) Intertrial interval (blank screen) for 500ms (editable)
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STIMULI
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Stimuli are provided by Millisecond Software. They can be replaced under
section EDITABLE CODE -> Editable stimuli.
The target stimulus was created in such a way, that the long arm is twice the length
of the short arm (which equals the length of the crossbar)
Note: The size of the target stimulus in this script is coded in terms of canvas screen %.
In order to achieve, a size that is roughly equal to the one used by Deary et al (2004),
go to stim picture.stim and follow instructions.
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INSTRUCTIONS
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Instructions are provided by Millisecond Software in the form of htm pages.
Instructions can be edited directly in file "IT_intro.htm"
or replaced entirely.
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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 Parameters:
/ trialsPerDuration = 20 //number of trials per stimulusduration (default: 20)
//!!!Note: if that number is changed, list.stimdurations/list.stimduration_condition
//(section Editable Lists) need to be changed accordingly
//=> 15 stimdurations x 20 trials/stimduration = 300 trials total
/ nrPracticeTrials = 25 //number of practice trials in this script.
//Note: the durations are selected at random.
//SIZING PARAMETERS
//sizing Parameters in RELATIVE measurements relative to CANVAS HEIGHT
//NOTE: to run the script with ABSOLUTE screen measurements, go to 'defaults' and set
//canvasSize to absolute measurements OR directly change the size of the stims
//under elements picture.stim
/ stimPicHeightPct = 26% //default height (in screen height %) (default: 26%)
//Note: Deary et al (2004): long arm = 5cm (short arm and cross bar = 2.5cm)
//you can set the height of the stim directly under element picture.stim
/ cueFontSizePct = 10% //default height (in screen height %) of the cue (default: 10%)
//Timing Parameters
/ readyDuration = 2000 //duration in ms of get-ready-trial (default: 2000)
/ cueDuration = 500 //duration of cue in ms (default: 500)
/ cueIsi = 600 //cue(offset)-stim(onset) Interstimulus Interval in ms (default: 600)
/ maskDuration = 500 //duration of mask in ms (default: 500)
/ iti = 500 //inter trial interval in ms (measured from response to onset of cue) (default: 500ms)
//stores the 15 stimulus presentation durations in ms
//Note: Deary et al (2004) used: 6, 12, 19, 25, 31, 37, 44, 50, 62, 75, 87, 100, 125, 150, 200 ms
//on a monitor with a vertical refresh rate = 160Hz
//!!! Most monitors have a vertical refresh rate of 60Hz and therefore it won't be possible
//to present any stimuli at 6 or 12 ms. One these computers it takes about 17ms
//to refresh the screen.
/ stimDuration1 = 6
/ stimDuration2 = 12
/ stimDuration3 = 19
/ stimDuration4 = 25
/ stimDuration5 = 31
/ stimDuration6 = 37
/ stimDuration7 = 44
/ stimDuration8 = 50
/ stimDuration9 = 62
/ stimDuration10 = 75
/ stimDuration11 = 87
/ stimDuration12 = 100
/ stimDuration13 = 125
/ stimDuration14 = 150
/ stimDuration15 = 200
//Response Keys:
/ responseKeyLeft = "A"
/ responseKeyRight = "L"
