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										LETTER MEMORY TASK (written input)

Script Author: Katja Borchert, Ph.D. ( for Millisecond Software, LLC
(reusing some interface code by David Nitz)
Date: 10-26-2016
last updated: 11-01-2019 by K.Borchert ( for Millisecond Software LLC

Script Copyright © 11-01-2019 Millisecond Software


This script implements the Letter Memory Task described in:

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

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.

The default data stored in the data files are:

(1) Raw data file: 'lettermemorytask_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) 
/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)
values.ACC:					the correctness of the response (1 = correct (here: all letters were correctly recalled); 0 = otherwise)
/countCorrectLetters:			stores the number of letters correctly recalled for the current trial (min: 0 - max: 3)

(2) Summary data file: 'lettermemorytask_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)

only test trials considered:
/propCorrect:					proportion correct test trials (proportion of trials where all 3 letters were correctly recalled -in any order)
/mean_correctLetters:			mean number of letters correctly recalled per test trial (across set sizes)

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

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

not original. Instructions are provided by Millisecond Software in the form of htmlpages.
These instructions can be edited directly in the html-files with simple text editors such as Notepad(Win) or TextEdit(Mac)

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:

/fixationDuration:					the duration (in ms) of the fixation cross (default: 1000ms)
/letterDuration:					the duration (in ms) of each letter (default: 2500ms)
/stimSize:							the size of each letter in proportion of the canvas height (default: 8%)
/ITI:								the duration of the intertrial interval (in ms) presented after feedback (default: 0)

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