Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 10, 2025
Last Modified: January 11, 2025 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
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.
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
4 minutes
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.
(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)
provided by Millisecond - can be edited under section 'Editable Stimuli'.
provided by Millisecond - see script greyscales_instructions_inc.iqjs
File Name: xxx_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: 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 = Test was not completed 1 = Test was completed |
| 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 mean asymmetry score = −0.213; median = −0.250), |
| meanSelectionRT | Mean selection RT (in ms) of response stimuli |
File Name: XXX_raw*.iqdat
| Name | Description |
|---|---|
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| 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) 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 |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Color Parameter |
||
| canvasColor | Display color of the actively used portion of the screen (the 'canvas') | gray |
| screenColor | Color of the screen not used by the canvas ('inactive screen') check section Defaults to change canvassize if needed | black |
| defaultTextColor | Default color of text items | black |
| topY | 40% | |
| bottomY | 60% | |
| maxImageWidthMM | The width/length of the longest grayscale in mm only change if you use other stimuli than the ones provided by this script! also check item.imageSize | 260 |
| minImageWidthMM | The width/length of the longest grayscale in mm only change if you use other stimuli than the ones provided by this script! also check item.imageSize | 120 |
| imageHeightMM | The height of the grayscale images in mm only change if you use other stimuli than the ones provided by this script! | 20 |
Timing Parameters |
||
| itiMS | The blank intertrial interval (in ms) btw. stimuli pair presentations | 500 |