PONE-D-21-01457

Effects of dual-task interference on swallowing in healthy aging adults

PLOS ONE

Dear Dr. Rangarathnam,

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Academic Editor

PLOS ONE

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Reviewers' comments:

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Comments to the Author

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Reviewer #1: Yes

Reviewer #2: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The study was aimed at investigating differences between young and old participants in their swallowing performance in basal conditions and during tasks engaging the left or right hemisphere. Results indicate that old age suppresses laterality differences and support the view that the left and right hemishere are involved in different parameters of swallowing.

The study is interesting and well conducted. The manuscript is well written.

Findings are relevant to basic and clinical science

Reviewer #2: The authors present a novel and well-written study into possible differences in hemispheric dominance and swallowing between groups of younger and older adults. Younger adults showed decrements to volume per time swallowing behaviours when performing silent word recognition (assumed left hemisphere dominant task) and facial recognition (assumed right hemisphere dominant task). Although older adults showed general decrements on all measures relative to younger adults, no dual-tasking related interference is observed.

I think that the study is well powered and the methodological detail is excellent. I just have the following comments:

Interpretation

The authors do well to clarify how it is important to not overreach conclusions regarding hemispheric dominance based on behavioural data alone. I think that the following interpretations should at least be considered in the discussion:

i) is it certain that the finding that older adults did not show a significant interaction on the volume per time measure of swallowing behaviour due to a floor effect? The VPT for older adults looks substantially lower than that for younger adults, and so I wonder what the range on this measure actually is - i.e. is the measure sensitive/appropriate to pick up interference in older adults?

ii) the interference task did not require an overt response. Therefore, could it be that older adults expressed greater performance decrements on the task for which there are no behavioural measurements?

Results

The results are clear but some critical details are missing that would inform interpretation and enable future meta-analyses - specifically, could the authors present attained p-values, effect sizes, and confidence intervals on those effect sizes?

Re: the figures - it is unclear what the error bars are depicting. Could the authors amend the figure captions to make this clear?

Figures 1-3 seem unnecessary, as the data are presented again in Figures 5-6.

Introduction

From the introduction on hemispheric specialization on swallowing, I was unclear exactly what the fMRI and PET data suggest re: hemispheric dominance - i.e. is it the left or the right hemisphere? Is the literature convergent in the findings?

The Daniels et al [27] paper seems particularly important for the study. It would be good to be able to understand how those specific conclusions were reached re: left vs right dominance for volume and temporal parameters of swallowing.

Re: the Malandraki et al [14] study - it is not clear what was found for the older adults and thus what could be concluded. I am guessing that there were no hemispheric differences in older adults, but was there a statistically significant age-group x laterality interaction?

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Reviewer #1: Yes: ENRICA L. SANTARCANGELO

Reviewer #2: Yes: Kelly Grace Garner

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Effects of dual-task interference on swallowing in healthy aging adults

PONE-D-21-01457R1

Dear Dr. Rangarathnam,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Giovanni Petri, Ph.D.

Academic Editor

PLOS ONE

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Reviewers' comments: