Return to the Dichotic Listening Task (Digits) page

Script Author: Katja Borchert, Ph.D. ( for Millisecond Software, LLC
Date: 04-03-2012
last updated: 01-15-2016 by K.Borchert ( for Millisecond Software LLC

Copyright © 01-15-2016 Millisecond Software


This script implements a variant of the dichotic listening task using digits as described in:

Koch, I., Lawo, F., Fels, J.  & Vorlaender, M. (2011). Switching in the Cocktail Party: Exploring Intentional Control of 
Auditory Selective Attention. Journal of Experimental Psychology: HPP, 37, 1140 - 1147

Participants listen to 2 digits (1-9, no 5) simultaneously played in the left and the right ear, one spoken by a female 
and the other by a male voice. In each trial a colored cue (here: @) signals which of the two genders presents the target digit.
The task is to decide if the target digit is less than or greater than 5.

The default data stored in the data files are:

(1) Raw data file: 'DichoticListening_Digits_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 ( used to counterbalance color)
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) 
smallerkey/largerkey:			the scancode for the "smaller"/"larger" keys
colorname1/colorname2:			hold the NAME of the two colors
blockcount:						counts the experimental blocks run
expcondition:					the experimental condition run:
									0 = starttrial; 
									1 = switch-congruent; 2 = switch-incongruent; 
									3 = repeat-congruent; 4 = repeat-incongruent
genderattention:				1 = pay attention to female voice; 2 = pay attention to male voice
gender_left/gender_right:		the gender of the voice in the left/right ear, 1 = female; 2 = male
digit_left/digit_right:			the digits to play in each ear
index_left/index_right:			the index number of the left/right soundfile to be played

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

(2) Summary data file: 'DichoticListening_Digits_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						group subject was assigned to
										group1: females color1; males color2
										group2: females color2; males color1
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; 1 = script was completed (all conditions run)

sc_corrcount - ric_corrcount:		counts the correct trials in each of the 4  experimental conditions
rtsum_sc - rtsum_ric:				sums up reaction time of correct trials, separate for each exp. condition
meanrt_sc - meanrt_ric:				mean reaction time of correct trials, separate for each exp. condition

* 2 levels of auditory attention switch (switch vs. repeat) x 2 levels of congruence of digits (congruent vs. incongruent)
=> 4 experimental conditions
 (1) Auditory Attention Switch: tested within
Switch: if participant had to pay attention to male (female) channel in previous trial, participant is asked to pay attention to female
(male) channel for the current trial
Repeat: pay attention to the same gender in the current trial
(2) Congruence: tested within
Congruent: both digits are less (greater) than 5
Incongruent: one digit is greater and one is less than 5
* Color Assignments counterbalanced by groupnumber

(1) Experimental
* run 1 starttrial + 144 experimental trials (36 per experimental condition)
(starttrial is excluded from analyses, it cannot be one of the 4 experimental conditions as it can neither switch nor repeat)
* the experiment runs 4 of these blocks
(2) Practice: short version of the Experimental condition: 1 starttrial + 24 experimental trials (no data recorded)

trial.switch_congruent, trial.switch_inconcruent, trial.repeat_congruent, trial.repeat_incongruent (trial.starttrial)-> trial.response

* present a large @ sign in green and yellow (default) that signal to pay attention to male or female voice (counterbalanced for color-gender assignment) 
(by default there is a 800ms pretrialpause before the cue comes on, and the cue stays on for 500ms before the digits are spoken)
* determine gender to be attended according to experimental condition
* randomly assign gender to the left and right channel
* randomly select a digit for the left ear and depending on experimental condition, randomly select from the congruent or 
incongruent options for the right ear (excluding same digits for congruent condition, e.g. you cannot have "2" spoken in the left and right ear)
* randomly select one of the three soundfiles for each ear depending on digit and assigned gender
* sum up reaction times of correct responses and calculate corresponding mean (DV), separately for each condition
These data are recorded in the summary data file.

!!!NOTE!!!: Koch et al (2011) not only excluded the reaction times of the starttrials and reaction times of incorrect trials but also excluded
reaction time of trials with reaction times that exceed 3STDs of the mean. This script simply excludes data from starttrials as well as
reaction times of incorrect trials.

*3 soundfiles per digit per gender (3 different voices) = 2 * 3 * 9 = 54 (minus 6 soundfiles for digit 5 that are included for algorithm purposes only)
!!!NOTE!!!!: the script has the necessary set-up to support using 3 sounfiles per gender per digit, however, at this point only one actual soundfile per
gender per digit is included. To add the remaining soundfiles go to Stimuli Item.digitsounds.

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:

cuepresentation:					the duration of the cue before the soundfiles are played in ms (default: 500)
pre_cuepresentation:				the pause before the cue comes on in ms (default: 800)
smallerkey/largerkey:				the scancode for the "smaller" (16->Q)/"larger" keys (25->P)
color_1/color_2:					the colors associated with gender
										Note: Assignment is counterbalanced by groupnumber
colorname1/colorname2:				string variables that holds the NAME of the two colors

Note: if you change the colors and/or key scancodes, you need to make appropriate changes to

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