Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: October 04, 2013
Last Modified: August 10, 2026 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements the Symbol Counter Task to study allocation of attentional resources within working memory.
The implemented procedure is based on Garavan et al (2000)
Garavan, H., Ross, T.J., Li, S.J., & Stein, E.A. (2000). A parametric manipulation of central executive functioning. Cereb Cortex, 10, 585-92.
18 minutes
Participants are presented 18 sequences of small and big squares and have to keep a separate count for each of the two squaretypes. Afterwards, participants are asked to select the count for each squaretype out of 20 possible options and receive feedback.
6 number of sequential squares x 3 types of switchFrequencies (high, medium, low) = 18 trial sequences
• Number of Squares: 11, 12, 13, 14, 15, 16
• Switch Frequencies: number of times the sequence switches from one symbol to the other
high -> floor(number of squares /2); e.g. floor(15/2) = 7
medium -> floor (number of squares/4); e.g. e.g. floor(15/4) = 3
low -> 1
TRIAL SEQUENCE:
trial.start
trial.presentSquares (loops until all squares are presented)
-> surveyPage.symbolCount
-> trial.feedback
-> trial.rest
•observed trial sequence (default):
repeat for as many squares as need to be shown (trial.presentSquares)
• fixation cross for 100ms
• square for 1500ms
Then:
• select correct counts out of 20 possible options (0-20); maximum time to accomplish this is
12s (surveyPage.symbolCount)
• receive feedback in the form of correct counts for 1000ms (trial.feedback)
• rest for a predetermined amount of time before next trial starts (a clock presents number of seconds)
(trial.rest)
=> 18 trials divided into 2 parts by a longer rest
2 types of black squares: small vs big
presented in form of pictures that can be easily substituted
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).
See script 'symbolcountertask_instructions_inc.iqjs'
File Name: symbolCountertask_summary*.iqdat
| Name | Description |
|---|---|
| startDate | Date the session was run |
| startTime | Time the session was run |
| subjectId | Participant ID |
| groupId | Group number |
| sessionId | Session number |
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| elapsedTime | Session duration in ms |
| completed | 0 = Test was not completed 1 = Test was completed |
| totalCorrect | Number of times participants was correct on both counts |
| pctTotalCorrect | Percentage of times participant was correct on both counts |
By Switch Intensity (Si) |
|
| propCorrectSI1 | Proportion of trials with switch intensity level 1 that participants was correct on both counts |
| propCorrectSI2 | Proportion of trials with switch intensity level 2 that participants was correct on both counts |
| propCorrectSI3 | Proportion of trials with switch intensity level 3 that participants was correct on both counts |
| meanErrorSI1 | Mean number of errors (absolute difference in actual and reported counts) in trials with switch intensity level 1 |
| meanErrorSI2 | Mean number of errors (absolute difference in actual and reported counts) in trials with switch intensity level 2 |
| meanErrorSI3 | Mean number of errors (absolute difference in actual and reported counts) in trials with switch intensity level 3 |
File Name: symbolCountertask_raw*.iqdat
| Name | Description |
|---|---|
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| computer.touch | 0 = device has no touchscreen capabilities; 1 = device has touchscreen capabilities |
| computer.hasKeyboard | 0 = no external keyboard detected; 1 = external keyboard detected |
| blockcode | The name the current block (built-in Inquisit variable) |
| blocknum | The number of the current block (built-in Inquisit variable) |
| trialcode | The name of the currently recorded trial (built-in Inquisit variable) |
| trialnum | The 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. |
| squareNumber | The current length (number of squares presented); Default: 11, 12, 13, 14, 15, 16 |
| switchIntensity | The currently selected switchIntensity (1 = low; 2 = medium; 3 = high) |
| switchFrequency | The calculated switch frequency (based on squareNumber and switchIntensity) |
| switchPositions | A string variable that stores all switchPositions in order from lowest to highest |
| symbolOrder | String variable that stores the order of the presented symbols (1 = small; 2 = big ) |
| countSymbol1 | Counts the number of symbol1 (small squares) cards that have been presented |
| countSymbol2, | Counts the number of symbol2 (big squares) cards that have been presented |
| dropdown.countSymbol1.response | The participant's count of symbol 1 (small squares) cards |
| dropdown.countSymbol2.response | The participant's count of symbol 2 (big squares) cards |
| correctCount1 | 1 = participant counted symbol1 cards correctly 0 = participant did not count symbol1 cards correctly |
| correctCount2 | 1 = participant counted symbol2 cards correctly 0 = participant did not count symbol2 cards correctly |
| correct | 1 = both of participant's count are correct 0 = otherwise |
| error | Absolute difference between sum of actual counts (for symbol1 and symbol2) and the sum of the entered counts (for symbol1 and symbol2) |
| rt | Latency of response in ms (selecting the two counts) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Design |
||
| showCorrectCounts | Debug element if set to true: correctCounts are presented in red during the count selection trial false = counts are not presented | false |
| skipPractice | False = a practice sequence is run true = no practice is given | false |
Sizing Parameters |
||
| pictureHeight | The height of the symbol picture (relative to canvas height) | 50% |
Timing Parameters |
||
| fixationCrossPresentation | Fixation cross duration (in ms) | 100 |
| cardPresentationDuration | Duration of card presentation (in ms) | 1500 |
| responseDuration | Time participants have to select countnumbers (in ms) | 12000 |
| feedbackDuration | Time feedback (here: correct counts) is presented (in ms) | 1000 |
| restDurationRegular | Time of the resting trial between trial sequence (in ms) | 15000 |
| restDurationLong | Time of rest in between the first 9 trials and the second 9 trials (in ms) | 120000 |