Return to the Number Vigilance Test page
						
										Number Vigilance Task
									
SCRIPT INFO

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 09-25-2017
last updated: 09-26-2017 by K.Borchert (katjab@millisecond.com) for Millisecond Software LLC

Script Copyright © 09-26-2017 Millisecond Software


BACKGROUND INFO 

											*Purpose*
This script implements a computerized Number Vigilance Task similarly to the one 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


The Number Vigilance Task is used as a subtest of 
the Cognitive Drug Research Computerized Assessment System (COGRAS).
It's a go/no go task with digits.


											  *Task*
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.								  


DATA FILE INFORMATION: 
The default data stored in the data files are:

(1) Raw data file: 'numbervigilance_raw*.iqdat' (a separate file for each participant)*

build:							Inquisit build
computer.platform:				the platform the script was run on
date, time, subject, group:		date and time script was run with the current subject/groupnumber 
blockcode, blocknum:			the name and number of the current block
trialcode, trialnum: 			the name and number of the currently recorded trial
									(Note: not all trials that are run might record data; by default data is collected unless /recorddata = false is set for a particular trial/block) 
/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" vs. "miss" vs. "CR" vs. "FA"									
correct:						accuracy of response: 1 = correct response; 0 = otherwise
latency: 						the response latency (in ms); measured from:


(2) Summary data file: 'numbervigilance_summary*.iqdat' (a separate file for each participant)*

script.startdate:				date script was run
script.starttime:				time script was started
script.subjectid:				subject id number
script.groupid:					group id number
script.elapsedtime:				time it took to run script (in ms)
computer.platform:				the platform the script was run on
/completed:						0 = script was not completed (prematurely aborted); 1 = script was completed (all conditions run)
/nrTestTrials:					the number of test trials run (default: 100)
/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
/propCorrect:					overall proportion correct (across all test trials)
/HITrate:						hitrate (across test trials that presented a target digit)
/FArate:						false alarm rate (across test trials that presented a foil digit)
/z_HITrate:						z-score of hit rate
/z_FArate:						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

* separate data files: to change to one data file for all participants (on Inquisit Lab only), go to section
"DATA" and follow further instructions


EXPERIMENTAL SET-UP

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)
Note: 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


STIMULI
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)

INSTRUCTIONS
provided by Millisecond Software - can be edited under section Editable Instructions

EDITABLE CODE:
check below for (relatively) easily editable parameters, stimuli, instructions etc. 
Keep in mind that you can use this script as a template and therefore always "mess" with the entire code to further customize your experiment.

The parameters you can change are:

/digitSOA_practice:					the stimulus onset asynchrony (in ms) during practice trials (default: 1000ms)
											Note: participants have the entire SOA to respond
/digitPresentationTime_practice:	the presentation duration (in ms) of the current trial digit (default: 1000ms)
											Note: if digitPresentationTime_practice > digitSOA_practice, it's automatically set to digitSOA_practice
/digitSOA_test:						the stimulus onset asynchrony (in ms) during practice trials (default: 750ms)
											Note: participants have the entire SOA to respond
											Note: 1 word/750ms => 80 words/minute
/digitPresentationTime_test:		the presentation duration (in ms) of the current trial digit (default: 750ms)
											Note: if digitPresentationTime_practice > digitSOA_practice, it's automatically set to digitSOA_practice
/errorFeedbackDuration:				the duration (in ms) of the error feedback during practice (default: 5000ms)
/readyDuration:						the duration (in ms) of the 'get ready trial' (default: 5000ms)

/nrPracticeTrials:					the number of practice trials run (default: 20)
											Note: uses the same target: foil rate as the test
											Note: if set to 0, the practice session is simply skipped
/nrTestTrials:						the number of test trials run (default: 100)
/targetRate:						the proportion of targets during the test (and practice) (default: 25%)
											Note: the proportion of targets should result in an integer
											Example: 100 test trials * 0.25 targets = > 25 targets

/targetDigitSize:					the proportional size of the digits on screen (default: 20%)

/responseKey:						the scancode of the response key (default: 57)
											Note: see Tools -> Keyboard Scancodes
/responseKey_label:					the label of the response key (57 -> "")


Copyright © Millisecond Software. All rights reserved.
Contact | Terms of Service | Security Statement | Employment