Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Created: January 25, 2017
Last Modified: January 04, 2024 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
Adjustments to z-scores as described by: Gregg, A. & Sedikides, C. (2010). Narcissistic Fragility: Rethinking Its Links to Explicit and Implicit Self-esteem, Self and Identity, 9:2, 142-161 (p.148)
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 Spacebar. 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 used for practice and test session.
1. Practice Block: (optional)
- number of practice trials can be set under section Editable Parameters (default: 20)
if set to 0, the practice trials are skipped. Instructions automatically adapt.
- proportion of target trials can be set under section Editable Parameters (default: 25%)
- order of target and foil trials is random
- selection of foil digits is random with replacement
- SOA and digit presentation duration can be set under section Editable Parameters
(SOA: 1000ms; digit presentation duration: 1000ms)
2. Test Block:
- number of test trials can be set under section Editable Parameters (default: 100)
- proportion of target trials can be set under section Editable Parameters (default: 25%)
- order of target and foil trials is random
- 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 |
| propCorrect | Overall proportion correct (across all test trials) |
| parameters.nrTestTrials | The number of test trials run (default: 100) |
| parameters.targetRate | The proportion of targets (signals) during the test (and practice) (default: 25%) |
| list.hits.itemCount | The number of target (signal) trials during the test |
| hitRate | Hitrate (across test trials that presented a target digit) = pressed spacebar for a target |
| missRate | Miss-rate (across test trials that presented a target digit) = did NOT press spacebar for a target |
| faRate | False alarm rate (across test trials that presented a foil digit) = pressed spacebar for a nontarget |
| crRate | Correct rejection rate (across test trials that presented a foil digit) = did NOT press spacebar for a nontarget z-score calculations: adjustments (see Gregg & Sedikides, 2010, p.148) If the hit rate / FA rate is 0 => 0.005 is used instead (aka 0.005 is added to the hit/FA rate) IF the hit rate / FA rate is 1.0 => 0.995 is used instead (aka 0.005 is subtracted from the hit/FA rate) |
| z-score of Hit Rate | Z-score of hit rate |
| zFaRate | Z-score of false alarm 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) |
| hitRT | The mean hit latency (in ms) |
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) 57 => spacebar was pressed 0 = no response |
| responseCategory | "hit" (pressed spacebar for a target) "miss" (did not press spacebar for a target) = omission error "CR" (did not press spacebar for a nontarget) = correct rejection "FA" (pressed spacebar 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 |
|---|---|---|
| digitSOAPractice | The stimulus onset asynchrony (in ms) during practice trials participants have the entire SOA to respond | 1000ms |
| digitPresentationTimePractice | The presentation duration (in ms) of the current trial digit if digitPresentationTime_practice > digitSOA_practice, it's automatically set to digitSOA_practice | 1000ms |
| digitSOATest | The stimulus onset asynchrony (in ms) during practice trials participants have the entire SOA to respond 1 word/750ms => 80 words/minute | 750ms |
| digitPresentationTimeTest | The presentation duration (in ms) of the current trial digit if digitPresentationTime_practice > digitSOA_practice, it's automatically set to digitSOA_practice | 750ms |
| errorFeedbackDuration | The duration (in ms) of the error feedback during practice | 5000ms |
| readyDuration | The duration (in ms) of the 'get ready trial' | 5000ms |
| nrPracticeTrials | The number of practice trials run uses the same target: foil rate as the test if set to 0, the practice session is simply skipped | 20 |
| nrTestTrials | The number of test trials run | 100 |
| targetRate | The proportion of targets during the test (and practice) the proportion of targets should result in an integer Example: 100 test trials * 0.25 targets = > 25 targets | 25% |
| targetDigitSize | The proportional size of the digits on screen responseKeys | 20% |
| responseKey | The response key | " " -> spacebar |