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The Effects of Task Difficulty Predictability and Noise Reduction on Recall Performance and Pupil Dilation Responses
Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences. Oticon AS, Denmark. (Linnaeus Centre HEAD)
Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences. (Linnaeus Centre HEAD)ORCID iD: 0000-0001-7311-9959
Eriksholm Res Ctr, Denmark.
Eriksholm Res Ctr, Denmark; Tech Univ Denmark, Denmark.
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2021 (English)In: Ear and Hearing, ISSN 0196-0202, E-ISSN 1538-4667, Vol. 42, no 6, p. 1668-1679Article in journal (Refereed) Published
Abstract [en]

Objectives: Communication requires cognitive processes which are not captured by traditional speech understanding tests. Under challenging listening situations, more working memory resources are needed to process speech, leaving fewer resources available for storage. The aim of the current study was to investigate the effect of task difficulty predictability, that is, knowing versus not knowing task difficulty in advance, and the effect of noise reduction on working memory resource allocation to processing and storage of speech heard in background noise. For this purpose, an "offline" behavioral measure, the Sentence-Final Word Identification and Recall (SWIR) test, and an "online" physiological measure, pupillometry, were combined. Moreover, the outcomes of the two measures were compared to investigate whether they reflect the same processes related to resource allocation. Design: Twenty-four experienced hearing aid users with moderate to moderately severe hearing loss participated in this study. The SWIR test and pupillometry were measured simultaneously with noise reduction in the test hearing aids activated and deactivated in a background noise composed of four-talker babble. The task of the SWIR test is to listen to lists of sentences, repeat the last word immediately after each sentence and recall the repeated words when the list is finished. The sentence baseline dilation, which is defined as the mean pupil dilation before each sentence, and task-evoked peak pupil dilation (PPD) were analyzed over the course of the lists. The task difficulty predictability was manipulated by including lists of three, five, and seven sentences. The test was conducted over two sessions, one during which the participants were informed about list length before each list (predictable task difficulty) and one during which they were not (unpredictable task difficulty). Results: The sentence baseline dilation was higher when task difficulty was unpredictable compared to predictable, except at the start of the list, where there was no difference. The PPD tended to be higher at the beginning of the list, this pattern being more prominent when task difficulty was unpredictable. Recall performance was better and sentence baseline dilation was higher when noise reduction was on, especially toward the end of longer lists. There was no effect of noise reduction on PPD. Conclusions: Task difficulty predictability did not have an effect on resource allocation, since recall performance was similar independently of whether task difficulty was predictable or unpredictable. The higher sentence baseline dilation when task difficulty was unpredictable likely reflected a difference in the recall strategy or higher degree of task engagement/alertness or arousal. Hence, pupillometry captured processes which the SWIR test does not capture. Noise reduction frees up resources to be used for storage of speech, which was reflected in the better recall performance and larger sentence baseline dilation toward the end of the list when noise reduction was on. Thus, both measures captured different temporal aspects of the same processes related to resource allocation with noise reduction on and off.

Place, publisher, year, edition, pages
Lippincott, Williams & Wilkins , 2021. Vol. 42, no 6, p. 1668-1679
Keywords [en]
Free recall; Noise reduction; Pupillometry; Task difficulty predictability; Working memory
National Category
Other Medical Sciences not elsewhere specified
Identifiers
URN: urn:nbn:se:liu:diva-180896DOI: 10.1097/AUD.0000000000001053ISI: 000710619100017PubMedID: 33859121OAI: oai:DiVA.org:liu-180896DiVA, id: diva2:1609645
Note

Funding Agencies|William Demant Foundation

Available from: 2021-11-09 Created: 2021-11-09 Last updated: 2021-12-28
In thesis
1. Cognition Seen Through the Eyes of Hearing Aid Users: Working Memory Resource Allocation for Speech Perception and Recall
Open this publication in new window or tab >>Cognition Seen Through the Eyes of Hearing Aid Users: Working Memory Resource Allocation for Speech Perception and Recall
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Kognition sett genom hörapparatanvändares ögon : Fördelning av arbetsminnesresurser vid uppfattning och återgivning av tal
Abstract [en]

This thesis investigates how hearing aid users allocate working (WM) memory resources under various task demands when listening to and storing speech in memory for later recall. This was done by combining an auditory recall task, the Sentence-final Word Identification and Recall (SWIR) test, with pupillometry. Different pupillary responses were used to obtain insights into momentary WM resource allocation and overall WM resource allocation over time. The task demands were manipulated by varying hearing aid noise reduction settings, as well as by varying the task difficulty of the SWIR test and the task difficulty predictability.

The findings from the first two studies showed that recall performance in competing speech was better, and baseline pupillary responses were higher when noise reduction was activated compared to when it was not. This indicates that attenuating background noise frees up WM resources to be used for storing speech in memory rather than speech processing. While unpredictable task difficulty elicited higher baseline pupillary responses than predictable task difficulty, it did not have any effect on recall performance. This finding suggests that task difficulty predictability does not affect WM resource allocation. Instead, unpredictable task difficulty may lead to increased alertness in anticipation of the end of the SWIR test list. The findings of the third study showed that increased transient task-evoked pupillary responses, which reflect the momentary intensity of attention during encoding, were associated with a higher likelihood of subsequent recall. Moreover, higher WM capacity was also linked to higher likelihood of subsequent recall, presumably due to the ability to allocate more attentional resources during encoding. Lastly, the findings from the fourth study indicated that the combination of the SWIR test and pupillometry is suitable for capturing WM resource allocation. Although arousal decreased over time, recall performance remained stable, suggesting that participants did not reach the point of disengagement.

Overall, a novel learning from this thesis is that increased pupillary responses may be a marker of “successful effort” when additional WM resources are allocated to achieve a better recall performance in the SWIR test. Furthermore, this thesis gives insights into which factors affect WM resource allocation and how to reduce the amount of processing resources required to understand speech, which may contribute to optimizing auditory rehabilitation in the future.

Abstract [sv]

Hörapparatanvändare upplever ofta lyssnande som ansträngande även när talet är tillräckligt högt för att kunna uppfattas mot en bakgrund av störande brus. I denna avhandling undersöks hur hörapparatanvändare fördelar sina arbetsminnesresurser under olika lyssningsbetingelser med olika krav på lyssning och lagring av tal för senare återgivning. Detta genomfördes genom att kombinera en auditiv återgivningsuppgift, Sentence-final Word Identification and Recall (SWIR) testet, med mätning av pupillstorlek. Resultaten visar att olika mått på pupillstorlek mäter olika aspekter av arbetsminnesresurser. Tillfälliga pupillökningar tyder på intensifierad uppmärksamhet och bättre minnesinkodning, medan den allmänna baslinjenivån på pupillstorleken också påverkar minnet över längre tidsperioder. Ett nytt resultat är att ökad pupillstorlek visar att "lyckad ansträngning" när de åtföljs av bättre återgivning av SWIR materialet. Dessutom ger brusreduktion i hörapparatens signalbehandling mera arbetsminnesresurser för minneslagringen. Avhandlingen ger fördjupade insikter i hur arbetsminnesresurser resurser allokeras, vilket i sin tur kan medföra optimering av signalbehandlingen i framtida hörapparater.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2022. p. 54
Series
Linköping Studies in Arts and Sciences, ISSN 0282-9800 ; 826Studies from the Swedish Institute for Disability Research, ISSN 1650-1128 ; 103
Keywords
Working memory, Free recall, Pupillary responses, Noise reduction, Arbetsminne, Återgivning, Pupillmätning, Brusreducering
National Category
Medical and Health Sciences Otorhinolaryngology
Identifiers
urn:nbn:se:liu:diva-181627 (URN)10.3384/9789179291389 (DOI)9789179291372 (ISBN)9789179291389 (ISBN)
Public defence
2022-02-04, TEMCAS, T-building, Campus Valla, Linköping, 10:00 (English)
Opponent
Supervisors
Available from: 2021-12-22 Created: 2021-12-06 Last updated: 2022-01-17Bibliographically approved

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