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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: 03-09-2020 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 03-09-2020 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 short 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 FILE INFORMATION
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The default data stored in the data files are:
(1) Raw data file: 'inspectiontimetask_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)
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
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
values.counttrials: counts all stim trials
values.stimduration: duration (in ms) of current stim
values.stimduration_conditio1-15 (depending on stimduration)
values.location: 1 = left shorter arm; 2 = right shorter 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' (a separate file for each participant)
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).
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.propcorre:ct_stim1: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 short 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),
edit parameters.skip_stimsizecalibration under section EDITABLE CODE -> Editable Values
(default: true -> stim size calibration routine is not run).
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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:
/responsekey_left: the left response key (default: 'A')
/responsekey_right: the right response key (default: 38)
/trials_perduration: 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
/nr_practicetrials: number of practice trials in this script.
Note: the durations are selected at random.
/fontsize_cue: default height (in screen height %) of the cue (default: 10%)
/skip_stimsizecalibration: false: the picture stimulus can be sized to 5cm (Deary et al, 2004) prior to start of experiment on current monitor
true: the calibration routine is skipped (default)
/stimpic_height: default height (in screen height %) (default: 26%)
Note: Deary et al (2004): long arm = 5cm (short arm and cross bar = 2.5cm)
Note: absolute sizing requires calibration for the current monitor
which is run if parameters.skip_stimsizecalibration = false (see below)
/stimpic_height_in_mm: default height of stimulus in mm (default: 5cm = 50mm)
will be used if 'skip_stimsizecalibration = false'
/ readyDuration: duration in ms of get-ready-trial (default: 2000)
/cueduration: duration of cue in ms (default: 500)
/cue_ISI: cue(offset)-stim(onset) Interstimulus Interval in ms (default: 600)
/maskduration: duration of mask in ms (default: 500)
/iti: inter trial interval in ms (measured from response to onset of cue) (default: 500ms)
/stimduration1-
/stimduration15: 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.