Dichotic Listening Task
Background
Dichotic Listening tasks are psychological tests used to investigate selective attention and how the brain processes auditory information played into both ears simultaneously. A typical finding of dichotic listening tasks is that most people have a right ear advantage for language-related stimuli because the right ear sends its signal directly for processing to the left hemisphere which is associated with language processing. This finding established dichotic listening tasks as a non-invasive tool to study brain asymmetry and language lateralization.
Donald Broadbent pioneered attention research with dichotic listening tasks in the early 1950s leading to his famous 'Filter Model of Attention', which suggests the brain selects only one "channel" of information to process at a time. Anne Treisman, one of his students, refined his theory after observing that highly relevant or expected words (like your own name) could "slip through" the filter. She proposed that the brain uses an 'attenuator' that dims the unattended message but does not turn it off. One famous demonstration of this 'attention attenuator' is the so-called 'Cocktail Party Effect': Even if you focus on one conversation at a party (and tune out all others), the moment you hear your name spoken somewhere else in the room, your attention switches over to this previously 'unattended' conversation (and you might even recall parts of the conversation that were said before your name was said).
In a typical dichotic listening task, a participant wears headphones and hears two different auditory stimuli (e.g. digits or syllables) spoken simultaneously into the left and right ear. In some procedures, participants receive prior cues to focus on a specific channel to either repeat the message from that particular ear ('shadowing') or use the learned information in some other way. Some dichotic listening tasks also add tasks to assess how much information people retain from the 'unattended' ear.
Millisecond offers several dichotic listening procedures. Three of those are described below.
(1) Lateralization Dichotic Listening Task
In a basic lateralization dichotic listing procedure such as the one used by the Behavioural Laterality Battery (Parker et al, 2020), participants hear different syllables such as 'ta' and 'da' simultaneously played in their right and left ear and are asked to indicate the syllable they heard best.
Task Procedure
Participants are first introduced to the six syllables (da,ba,ga,ta,ka,pa) used in the task. Each syllable can be replayed as often as needed. Once they have been familiarized with the stimuli, they start a practice session that runs 9 trials. During all trials the stimuli are played into the left and right ear simultaneously. Six of the practice trials play the same syllables (e.g. da-da) into both ears and three trials play different ones (da-ba, ga-ta, ka-pa). The order of the practice trials is randomly determined. Participants listen to the syllables and have to decide which syllables they heard (best), by selecting one of six response buttons, one for each syllable. No feedback is provided. The four test blocks run all 36 syllable combinations in random order.
What it Measures
The Lateralization Dichotic Listening Task is a measure of selective attention and language lateralization
Main Performance Metrics
- Lateralization Index: ratio score that compares number of correct responses when left sound was selected to those when the right sound was collected
(2) Priming Dichotic Listening Task
In a priming dichotic listening task (Saetrevik & Hugdahl, 2007) participants may be instructed to listen to a specific ear channel (e.g. the left ear). Before the target stimuli (syllables such as 'ta' and 'da') are played into the left and right ear, participants hear a priming syllable (played into both ears).
Task Procedure
In each trial, priming syllables (e.g. da-da) are played into both ears. After a 500ms delay, the target stimuli (e.g. da-ga) follow. The response Screen provides six possible response buttons arranged in a clockwise circle, and participants are asked to select the target syllable they heard. Participants work through three different instruction conditions that specify the target ear they should attend to:
- NF (not-forced): instructions don't specify which ear to pay attention to ("Select the one you heard best")
- LF (left-forced): instructions specify to pay attention only to the LEFT ear ("Select the left target")
- RF (right-forced): instructions specify to pay attention only to the RIGHT ear ("Select the right target") The NF condition always precedes the LF and RF conditions whose order is counterbalanced between participants.
Primes can be unrelated to the target syllables, or they can 'prime' the left/right target one. The three test blocks (NF, LF, RF) run a total of 240 trials, consisting of 8 repetitions of the 30 'inconsistent' syllable pairings. The trials are randomly distributed across the three instruction conditions. A short practice session before the NF condition is provided.
What it Measures
The Priming Dichotic Listening Task is a measure of selective attention and language lateralization under priming conditions
Main Performance Metrics
- Lateralization Index: ratio score that compares number of correct responses when left sound was selected to those when the right sound was collected
- Priming Index: ratio score that compares number of responses that match the prime to those where response and prime are mismatched
(3) Switch Cost Dichotic Listening Task
In the switch-cost dichotic listening procedure (Koch et al, 2011) participants hear different digits spoken by a male and female voice into the left and right ear. A prior cue tells participants which gender to listen to in order to answer if the digit is smaller or larger than 5. Trials can be 'repeat' (listen to same gender as before) or 'switch' trials (listen to a different gender than before).
Task Procedure
In each trial, participants see a yellow or green '@' symbol for 500ms. This colored cue signals which voice to listen to (e.g. green for female; yellow for male). Then two different digits (1-9, except 5) are played into the left and right ear, one digit spoken by a female voice (e.g. 'six') and one digit spoken by a male voide (e.g. 'four'). Participants have to decide whether the target digit is smaller or greater than '5' and press the 'Q' key for digits that are smaller and the 'P' key for digits that are larger. If the '@' cue was green, the correct response in this example would be 'P' (6 > 5). If the '@' was yellow, the correct response would be 'Q' (4 < 5).
Trials can be 'repeat' trials (same colored cue) or 'switch' trials (different colored cue). Correct responses can be 'congruent' (both digits would result in the same key-response) or 'incongruent' (the digits require different key responses).
Participants work through four test blocks of 144 trials, plus one start trial. Each block runs 36 repeat-congruent, 36 repeat-incongruent, 36 switch-congruent and 36 switch-incongruent trials. A practice block of 24 trials familiarizes participants with the procedure.
What it Measures
The Switch Cost Dichotic Listening Task is a measure of switch costs (executive control) in selective attention tasks
Main Performance Metrics
- Switch Costs: Difference score btw. performance in switch trials and repeat trials
Psychological domains
- Selective & Directed Attention: Ability to focus on a specific task
- Language Lateralization: Hemispheric asymmetry in language processing
- Executive Control: Collection of "top-down" mental processes used to manage and regulate thoughts and actions
- Cognitive Flexibility: Ability to shift to a new rule when the previous rule no longer applies
Psychiatric Conditions
The following patient groups show impacted performance on Dichotic Listening Tasks
- Attention Deficit Hyperactivity Disorder (ADHD)
- Dyslexia
- Schizophrenia
- Parkinson’s Disease (PD)
- Alzheimer’s Disease (AD)
- Traumatic Brain Injury
Test Variations
A test of ear dominance from the Behavioural Laterality Battery Dichotic Listening Task (Parker et al, 2020).
This implements a Dichotic Listening Task involving digits as described in Koch et al (2011).
This implements a Dichotic Listening Task involving presentation of word syllables as described in Saetrevik & Hugdahl (2007).
References
Search Google Scholar for peer-reviewed, published research using the Inquisit Dichotic Listening Task.
Studdert-Kennedy M., Shankweiler D. P. (1970). "Hemispheric specialization for speech perception". Journal of the Acoustical Society of America 48: 579–594
Hugdahl, K., & Andersson, L. (1986). The “Forced-Attention Paradigm” in Dichotic Listening to CV-Syllables: A Comparison Between Adults and Children. Cortex, 22, 417-432.
Saetrevik, B. & Hugdahl, K. (2007) . Endogeneous and exogeneous control of attention in dichotic listening. Neuropsychology, 21, 285-290.
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.
Bless, J. J., Westerhausen, R., Arciuli, J., Kompus, K., Gudmundsen, M., & Hugdahl, K. (2013). Right on all Occasions?” – On the Feasibility of Laterality Research Using a Smartphone Dichotic Listening Application. Frontiers in Psychology, 4, 42.
Parker, Adam J, Woodhead, Zoe V. J, Thompson, Paul A, & Bishop, Dorothy V. M. (n.d.). Assessing the reliability of an online behavioural laterality battery: A pre-registered study. Laterality (Hove), Ahead-of-print(Ahead-of-print), 1-39.