Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
(reusing some interface code by David Nitz)
Created: January 26, 2016
Last Modified: January 30, 2025 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements the Letter Memory Task, a test of executive functioning focusing on continuously updating working memory representations.
The implemented procedure is similar to the one outlined by:
Friedman, N. P., Miyake, A., Young, S. E., DeFries, J. C., Corley, R. P., & Hewitt, J. K. (2008). Individual differences in executive functions are almost entirely genetic in origin. Journal of Experimental Psychology: General, 137, 201–225.
Note: this script collects written input at the end of each trial
10 minutes
Participants view series of letters (5, 7, 9), one at a time in the middle of the computer screen. Whenever a new letter comes on screen, they have to rehearse out loud the last 3 letters in the series. After the last letter disappears, they have to enter the last 3 letters by selecting the correct letters from a provided letter matrix.
3 set sizes tested: 5, 7, 9 (controlled by list.setSize under Editable Lists)
1. Practice: 3 practice trials (one per set size), order of set sizes randomly determined
(change number of trials under section BLOCKS)
2. Test: 12 trials (4 per set size), order of set sizes randomly determined with the
constraint that every set size appears once every 3 trials (change number of trials under section BLOCKS)
Trial Sequence:
Fixation (1000ms) ->
5-9 letters (2500ms per letter, letters randomly selected without repeat) ->
recall screen (until response) -> feedback (until response) -> ITI (0ms)
- 21 English consonants
- size can be controlled via editable parameters
Instructions are not original to the task. They are provided by Millisecond
as htm/html pages and can be edited by changing the provided htm/html files.
To edit htm/html-files: open the respective documents in simple Text Editors such as TextEdit (Mac)
or Notepad (Windows).
File Name: lettermemorytask_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| startDate | Date the session was run |
| startTime | Time the session was run |
| subjectId | Participant ID |
| groupId | Group number |
| sessionId | Session number |
| elapsedTime | Session duration in ms |
| completed | 0 = Test was not completed 1 = Test was completed |
| propCorrect | Proportion correct test trials (proportion of trials where all 3 letters were correctly recalled -in any order) |
| meanCorrectLetters | Mean number of letters correctly recalled per test trial (across set sizes) |
File Name: lettermemorytask_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, group, | With the current subject/groupnumber |
| session | Session number |
| blockCode | Name of the current block |
| blockNum | Number of the current block |
| trialCode | Name of the current trial |
| trialNum | Number of the current trial |
| currentsetSize | The current set Size used (default: 5, 7, or 9) |
| presentedLetters | Stores the presented letters (in the order they were presented) |
| recallDuration | Stores the duration (ms) of the recall (= difference in Start and End Time of recall screen) |
| response | The participant's response in the recorded trial |
| last3 | Stores the last 3 letters (in the order they were presented) |
| recalledLetters | Stores a string of 3 recalled characters (if more than 3 are selected, they get ignored by computer) |
| acc | The correctness of the response 1 = correct (here: all letters were correctly recalled; order not important) 0 = otherwise |
| countCorrectLetters | Stores the number of letters correctly recalled for the current trial (min: 0 - max: 3) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
| fixationDuration | The duration (in ms) of the fixation cross | 1000ms |
| letterDuration | The duration (in ms) of each letter | 2500ms |
| stimSize | The size of each letter in proportion of the canvas height | 8% |
| iti | The duration of the intertrial interval (in ms) presented after feedback | 0 |