Return to the Dichotic Listening Task (Syllables) page
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								DICHOTIC LISTENING TASK (Consonant-Vowel approach)
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Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com) for Millisecond Software, LLC
Date: 04-02-2012
last updated:  03-18-2020 by K. Borchert (katjab@millisecond.com) for Millisecond Software, LLC

Script Copyright © 03-18-2020 Millisecond Software

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BACKGROUND INFO 	
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This script implements the primed dichotic listening task using the Consonant-Vowel (CV) Nonsense Syllables 
approach described in:

Saetrevik, B. &  Hugdahl, K. (2007) . Endogeneous and exogeneous control of attention in dichotic listening. 
Neuropsychology, 21, 285-290.

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TASK DESCRIPTION	
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After hearing two nonsense syllables simultaneously spoken in the left and right ear, participants are asked to select their target
(=depends on instructions) out of 6 possible choices. The target depends on the instructions which
may specify the ear (left or right) to pay attention to. In this experiment, participants also listen to a prime syllable that is
played in both ears BEFORE the simultaneous probe syllables are played. The prime matches one of the two probe syllables or none.

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DURATION 
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the default set-up of the script takes appr. 20 minutes to complete

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

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

build:								The specific Inquisit version used (the 'build') that was run
computer.platform:				the platform the script was run on (win/mac/ios/android)
date, time, 						date and time script was run 
subject, group, 					with the current subject/groupnumber
script.sessionid:					with the current session id

blockcode, blocknum:			the name and number of the current block (built-in Inquisit variable)
trialcode, trialnum: 				the name and number of the currently recorded trial (built-in Inquisit variable)
										Note: trialnum is a built-in Inquisit variable; it counts all trials run; even those
										that do not store data to the data file.
									
primecondition:					0 = noprime, 1 = left; 2 = right (codes the current prime condition)
prime:								the index of the prime syllable
left:								the index of the left target
right:								the index of the right target

response:							the participant's response (e.g. selected button)
correct:							the correctness of the response (1 = correct; 0 = error)
latency: 							the response latency (in ms)

responseCategory:				0 = error (response does not match left or right syllable)
									1 = response matches left syllable
									2 = response matches right syllable

sumleftresponses/sumrightresponses:		total of all left matching/right matching responses(based on response category)	

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

Computer Platform:				the platform the script was run on (win/mac/ios/android)
Date:								date script was run
Time:								time script was started
Subject ID:							assigned subject id number
Group ID:							assigned group id number
Session ID:							assigned session id number
Script Duration:					time it took to run script (in ms); measured from onset to offset of script
Script Completion:				0 = script was not completed (prematurely aborted); 
									1 = script was completed (all conditions run)
									
sumleftresponses/sumrightresponses:		total of all left matching/right matching responses(based on response category)									

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EXPERIMENTAL SET-UP 
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Trial Flow:
Prime (both ears) ---500ms pause--> Targets (left/right ear) ---500ms---> Response Screen: 6 possible syllables arranged in a clockwise 
fashion

Experimental Design:
(I) 3 within subject instruction blocks 
1) NF (not-forced): instructions don't specify which ear to pay attention to  ("Select the one you heard best")
2) LF (left-forced): instructions specify to pay attention only to the LEFT ear ("Select the left target")
3) RF (right-forced): instructions specify to pay attention only to the RIGHT ear ("Select the right target")

After a short practice session (NF), the script starts every participant in condition NF. The order LF-RF / RF-LF is then counterbalanced 
between participants by groupnumber. There are 80 trials in each instruction condition (=240 trials total) 
(see Saetrevik & Hugdahl, 2007).

(II) 3 within priming conditions
1) No prime: the prime is unrelated to the target syllables
2) Left prime: the prime is the left target syllable
3) Right prime: the prime is the right target syllable
the 3 priming conditions are randomly sampled (without replacement) during each instruction condition: 
50% of the trials in each instruction conditions are noprimes (40trials), 25% are left primes (20trials), and 25% are right primes (20trials) 
(see Saetrevik & Hugdahl, 2007)

(III) Dichotic Listening Task (trial.dichotic: presentation of target syllables, trial.dichoticresponse: selection of target syllable out of 6 possible targets):
*6 possible syllables: ba, ga, ta, ka, pa, da (spoken by a male native American English speaker)
*30 different pairings (no pairings of same syllables)
=> 8 x 30 = 240 trials, randomly distributed over the three instruction conditions
Note: if only the dichotic listening task is of interest check out 
trial.dichotic: presentation of target syllables 
trial.dichoticresponse: selection of target syllables out of 6 possible targets
as well as the necessary stimuli that go with it.

!!!!!!!!!!!!!
NOTE: Difference between script and Saetrevik & Hugdahl (2007):
a) The x/y screen positions of the 6 possible syllables targets in a clocklike arrangement is randomly determined for each participant in the script.
It is counterbalanced by Saetrevik & Hugdahl (2007).
b) the pause between targets and response screen was not explicitly specified in Saetrevik & Hugdahl (2007) (to the best of our knowledge).
It is set to 500ms (default) in this script and can be easily edited under Editable Parameters.

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STIMULI
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sound files are provided by Millisecond Software. They can be easily replaced under section Editable Stimuli.
The current syllables are recorded by a Male American English Native Speaker.

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INSTRUCTIONS 
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Instructions are not original to the task. They are provided by Millisecond Software
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).
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EDITABLE CODE 
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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:

prime_posttrialpause:					sets the pause after the prime is presented in ms (default: 500ms)
dichotic_posttrialpause:				sets the pause after the dichotic pairs are presented in ms (default: 500ms)
dichoticresponse_posttrialpause:		sets the pause after the response is made in in ms (default: 800ms)