Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 08, 2020
Last Modified: January 10, 2025 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements a computerized Number Vigilance Task, a measure of attention and cognitive control. The Number Vigilance Task is used as a subtest of the Cognitive Drug Research Computerized Assessment System (COGRAS). The Number Vigilance Task is a type of go/no go task with digits.
The implemented procedure is similar to the one published in:
Nicholl, C.G. et al (1995). The the Cognitive Drug Research Computerized Assessment System in the evaluation of early dementia- is speed of the essence? INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, VOL. 10: 199-206
3 minutes
Participants view a stream of digits presented in the middle of the screen, one at a time. A new digit is presented ~750ms (for a presentation Rate of: 80 words/minute). Whenever the digit is the same as the target digit (which is presented on the right of the screen throughout the task), they have to press the 'Yes' key (here: Q-key). Otherwise they are instructed to not do anything but stay vigilant and wait for the next digit.
Target Digit: is sampled randomly at the start of the script.
The same target is throughout the test.
1. Test Block:
- number of test trials can be set under section Editable Parameters (default: 90)
- proportion of target trials can be set under section Editable Parameters (default: 30%)
- order of target and foil trials is random (constraint: first trial is a foil trial)
- selection of foil digits is random with replacement
- SOA and digit presentation duration can be set under section Editable Parameters
(SOA: 750ms; digit presentation duration: 750ms)
Trial Sequence:
• target is presented throughout the blocks to the right on the screen
• each block starts with the target presented alone for duration SOA
current digit presentation (750ms), response window = SOA = 750ms ->current digit presentation
target = randomly determined digit from 0 to 9, presented in black font on the right side of the screen
current digit = digit from 0 to 9, presented in black font in the center of the screen
both digits are equal in size (size can be set under section Editable Parameters)
provided by Millisecond - can be edited under section Editable Instructions
File Name: numbervigilance_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 |
| numberOfDigits | The number of digits presented (targets and nontargets) |
| numberOfTargets | The number of targets presented |
| numberOfFoils | The number of foils presented |
| propCorrect | Proportion correct responses (across targets and nontargets) |
| vigHit | The number of hit responses (pressing spacebar for target digits) |
| vigFA | The number of false alarms (pressing spacebar for foil digits) |
| vigAcc | The hitRate (proportion of targets that were correctly responded to) in Number Vigilance Test |
| vigMissRate | The miss rate (proportion of targets that were not responded to) |
| vigFARate | The false alarm Rate (proportion of non targets that were responded to) |
| vigCrRate | The correct rejection rate |
| dPrime | D' = sensitivity index calculated as difference btw. z score of hit rate and z-score of false alarm rate => Range (in this script) -5.1516586840152740479 <= dprime <= 5.1516586840152740479 (=perfect performance) => The higher the value, the better signals (=targets) were overall distinguished from noise (=nontargets) and thus the better participant paid attention (d' = 0: chance performance; negative d-primes: participant treated nontargets as targets and targets as nontargets) |
| c | C-criterion in signal detection:The absolute value of c provides an indication of the strength of the response bias/response style negative: participant more likely to report that signal (go stims) is present (liberal response style) may favor faster responding in speed-accuracy trade-off response paradigms positive: favoring caution (conservative response style) |
Response Times |
|
| vigRT | The mean response time (in ms) of correctly responding to a target in Number Vigilance Test |
File Name: numbervigilance_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 | Name of the current block |
| blockNum | Number of the current block |
| trialCode | Name of the current trial |
| trialNum | Number of the current trial |
| digitType | 1 = target digit (current digit = target digit) 2 = foil digit (current digit <> target digit) |
| targetDigit | The randomly selected target digit that is presented at the right of the screen |
| currentDigit | The currently randomly selected digit that is presented in the center of the screen |
| response | The participant's response (scancode of response button) 16 = yes-key was pressed 0 = no response |
| responseLabel | "yes" vs. "" (empty) |
| responseCategory | "Hit" (pressed yes-key for a target) "Miss" (did not press yes-key for a target) = omission error "CR" (did not press yes-key for a nontarget) = correct rejection "FA" (pressed yes-key for a nontarget) = commission error |
| correct | Accuracy of response 1 = correct response 0 = otherwise |
| latency | The response latency (in ms); measured from: onset of center digit |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
Stimsize |
||
| stimSize | The proportional size of the digits on screen | 20% |
Duration Parameters |
||
| firstStimDelay | The delay (in ms) of the first stim after pressing spacebar to start | 1000 |
| digitSOATest | The stimulus onset asynchrony (in ms) during test trials participants have the entire SOA to respond 1 word/750ms => 80 words/minute | 750 |
| digitPresentationTimeTest | The presentation duration (in ms) of the current trial digit if the presentation duration is longer than SOA, the presentation duration is automatically reduced to SOA | 750 |
Experimental Design Parameters |
||
| nrTestTrials | The number of test trials run | 90 |
| targetRate | The proportion of targets during the test (and practice) the proportion of targets should result in an integer Example: 90 test trials * 0.3 targets = > 27 targets | 0.3 |
Response Keys: Note This Script Only Requires The Yes-Key |
||
| leftKey | The left response key (here: Q) | "Q" |
| rightKey | The right response key (here: P) | "P" |
| yesKey | The assignment of left/right key to the yesKey (here Q); left keys will appear on the left on touch screens | parameters.leftKey |
| noKey | The assignment of left/right key to the noKey (here P); right keys will appear on the right on touch screens | parameters.rightKey |