German Version
German translation provided by K. Borchert for Millisecond Software
___________________________________________________________________________________________________________________
Greyscales Test
___________________________________________________________________________________________________________________
Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 04-10-2025
last updated: 04-11-2025 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC
Script Copyright © 04-11-2025 Millisecond Software
___________________________________________________________________________________________________________________
BACKGROUND INFO
___________________________________________________________________________________________________________________
This script implements a version of the Greyscales Test suggested by Mattingley et al (1994).
The Greyscales Test is a simple perceptual test to test attentional bias in unilateral
patients and healthy controls using mirror gradient rectangle pairs (the 'gray scales').
Normal adults tend to show a slight left bias (Mattingley et al, 2004) despite the images
having the same brightness overall.
//References:
Mattingley, J. B., Bradshaw, J. L., Nettleton, N. C., & Bradshaw, J.A. (1994).
Can task specific perceptual bias be distinguished from unilateral neglect?
Neuropsychologia, 32, 805–817.
Mattingley, J. B., Berberovic, N., Corben, L., Slavin, M. J., Nicholls, M. E. R., & Bradshaw, J. L. (2004).
The greyscales task: a perceptual measure of attentional bias following unilateral hemispheric damage.
Neuropsychologia, 42(3), 387–394. https://doi.org/10.1016/j.neuropsychologia.2003.07.007
___________________________________________________________________________________________________________________
TASK DESCRIPTION
___________________________________________________________________________________________________________________
Participants see pairs of stacked gradient rectangles of the same overall brightness.
One rectangle presents a black-to-white gradient rectangle; and the other
one presents its mirror image.
Participants are asked to select the rectangle that appears darker.
___________________________________________________________________________________________________________________
DURATION
___________________________________________________________________________________________________________________
the default set-up of the script takes appr. 4 minutes to complete
___________________________________________________________________________________________________________________
DATA OUTPUT DICTIONAIRY
___________________________________________________________________________________________________________________
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.
scalingProp: the scaling proportion in case the active canvas is not large enough to present
the largest stim (26cm).
range: 0 < scalingProp <= 1 (1 = no scaling necessary; screen is large enough)
scalingProp = 0.8 => the images are scaled down to 80% of their original sizes
imageHeightMM: the height of the presented images in mm
minImageWidthMM: the smallest image width of the presented images in mm
maxImageWidthMM: the largest image width of the presented images in mm
widthDiffMM: the approximate difference in width (in mm) btw. an image and the next larger one
trialCounter: tracks the number of trials run
pairIndex: index of the currently presented stimulus pair (0-7)
bwPosition: 0 = the black-to-white image is presented on top
1 = the black-to-white image is presented on the bottom
picture.bw.y: the y-coordinate of the black-to-white image (in canvas%)
picture.wb.y: the y-coordinate of the white-to-black image (in canvas%)
stimulusitem: presented stimuli
response: the response of participant (scancode of response button)
correct: correctness of response (1 = correct, 0 = error)
latency: response latency (in ms); measured from: onset of stims
bwCounter: number of 'black-to-white' image selections
(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)
scalingProp: the scaling proportion in case the active canvas is not large enough to present
the largest stim (26cm).
range: 0 < scalingProp <= 1 (1 = no scaling necessary; screen is large enough)
scalingProp = 0.8 => the images are scaled down to 80% of their original sizes
imageHeightMM: the height of the presented images in mm
minImageWidthMM: the smallest image width of the presented images in mm
maxImageWidthMM: the largest image width of the presented images in mm
widthDiffMM: the approximate difference in width (in mm) btw. an image and the next larger one
bwCounter: number of 'black-to-white' image selections
propBW: proportion of 'black-to-white' image selections
propWB: proportion of 'white-to-black' image selections
asymmetryScore: difference in propWB - propBW
Note: mean asymmetry score = −0.213; median = −0.250),
meanSelectionRT: mean selection RT (in ms) of response stimuli
___________________________________________________________________________________________________________________
EXPERIMENTAL SET-UP
___________________________________________________________________________________________________________________
(1) Intro with task comprehension question
(intro gets repeated if the participant fails the task comprehension question)
(2) Test: 32 trials
Design: 8 stimuli pairs x 2 position conditions (bw on top vs. bw on bottom) x 2 reps = 32 trials
* 8 stimuli pairs: absolute width 120mm-260mm with steps of 20mm (height of rectangles: 20mm)
(stimuli get scaled if current canvas not large enough, see below under STIMULI for more info)
- each stimulus pair consists of the black-to-white image (bw) and its mirror image white-to-black (wb)
- the empty space btw. the stimulus pair is set to be half the rectangle height
* each stimulus pair is presented 4 times; half the time the bw is on top; half the time the bw image is on the bottom
* order of stimuli is randomized (selectionmode: without replacement)
//Trial Sequence:
- presentation of stimulus pair until response (selection of 'darker' rectangle)
- 500ms iti (blank screen)
___________________________________________________________________________________________________________________
STIMULI
___________________________________________________________________________________________________________________
provided by Millisecond Software - can be edited under section 'Editable Stimuli'.
//////////////////////////
//Stimuli Generation:
//////////////////////////
8 stimuli were generated in Paint.net using the Gradient tool (black to white) with the
image sizes set to the appropriate cm measurements (width: 12cm-26cm; height: 2cm).
The 8 stimuli were then flipped horizontally to generate the mirror images.
=> each rectangle in a pair has the same brightness
//////////////////////////
//Stimuli Presentation:
//////////////////////////
The script checks that the current screen canvas* is big enough to present the
largest stim (width = 26cm).
* If yes, all stims are presented in their original sizes.
The height of the empty space btw.the two stacked images is
half the height of the rectangles (here: 1cm).
* If no, all stims are proportionally adjusted (width and height), so that the
largest stim can fit on the canvas.
The empty space btw. the images gets adjusted accordingly.
The data files will store the final absolute measurements of the smallest
and largest stim.
*canvas: by default, this script uses a 4:3 canvas on each screen it runs on
(see section Defaults)
___________________________________________________________________________________________________________________
INSTRUCTIONS
___________________________________________________________________________________________________________________
provided by Millisecond Software - see script greyscales_instructions_inc.iqjs
___________________________________________________________________________________________________________________
EDITABLE CODE
___________________________________________________________________________________________________________________
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:
//color parameter
/ canvasColor = gray //Display color of the actively used portion of the screen (the 'canvas')
/ screenColor = black //Color of the screen not used by the canvas ('inactive screen')
//Note: check section Defaults to change canvassize if needed
/ defaultTextColor = black //Default color of text items
/ topY = 40%
/ bottomY = 60%
/ maxImageWidthMM = 260 //The width/length of the longest grayscale in mm
//Note: only change if you use other stimuli than the ones provided by this script!
//also check item.imageSize
/ minImageWidthMM = 120 //The width/length of the longest grayscale in mm
//Note: only change if you use other stimuli than the ones provided by this script!
//also check item.imageSize
/ imageHeightMM = 20 //The height of the grayscale images in mm
//Note: only change if you use other stimuli than the ones provided by this script!
//timing parameters
/ itiMS = 500 //the blank intertrial interval (in ms) btw. stimuli pair presentations
