PONE-D-20-02249

Eyebrow position in grammatical and emotional expressions in Kazakh-Russian Sign Language: A quantitative study

PLOS ONE

Dear Dr. Kimmelman,

Thank you for submitting your manuscript to PLOS ONE, and especially for your patience with a review process that was much longer than ideal.  I judged that finding the well-qualified reviewers would ultimately serve this work better than finding less-qualified reviewers who might have had a faster turnaround.  I have now received reviews from three experts in the role of facial expressions in sign languages, and am happy to report that their impression of the manuscript is generally positive: I concur.  Reviewers 1 and 3 request several specific revisions; I encourage you to address them as clearly and specifically as possible in both the revised manuscript and a reply letter.  If your revisions are sufficiently clear, there may not be a need to re-circulate the manuscript for external review.  

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Matthew L. Hall, PhD

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: Yes

Reviewer #3: Partly

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

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Reviewer #1: It is great to see the field for automatic sign language analysis advancing, in particular for the painstaking analyses of facial expressions! My comments below are aimed at polishing this clearly structured and relevant paper.

For ease of reading consider the gender-neutral use of the pronoun “they” as an alternative to s/he.

Lines 77-93 Please note that de Vos et al.’s methodology (specifically sentence types) is not summarized accurately. That is to say, only a subset of the data (polar and content questions) were included in the analysis.

In line 135 the authors claim that “RSL and KRSL are closely related and very similar lexically”. For those unfamiliar with the political history, could you please say something more about when these languages may have started to diverge, and how likely it is that the two communities are still in regular contact.

Line 147-148 Kazakhstan’s government provides 60 free hours of sign language interpreter service support for each deaf person, which could be spent on medical, legal, or other communication needs.

>Are these hours given each year?

Line 200 Did you consider doing a debriefing/post-hoc interview? Why not?

Line 291 What was the frame rate?

Line 357-364 With respect to the pixel analysis, I would like to know whether you have evidence that these are actually perceivable differences for signers themselves?

Line 464-480 Do you think that the interpreters/CODAs may also have reacted differently because they were presented with different stimuli? (written text as opposed to signed videos).

Since you have set it up so nicely, I think it would be worthwhile revisiting de Vos et al.’s Affect over Grammar hypothesis in the conclusion section.

Reviewer #2: This is an excellent addition of a quantitative study of eyebrow movement in the first linguistic study of KRSL which also contributes to the pool of data from several other signed languages to advance the field using more automated means of data gathering then seen in previous studies.

The data were collected with a focus on constructed speech, while most signed language research tried to elicit sentences as if the signed felt the emotion. The authors assert that this allows for emotional expressions that are typical from this particular culture, rather than entering into the debate on whether there are universal facial expressions for emotion.

The methodology is sound for this type of research, and may influence future researchers using computers for data collection and facial measurements.

This was s great glimpse into a signed language that is new to research, and adds more insights into what may or may not change when affect and grammar overlay onto each other in emotional sentence structures. Instead of the affect over grammar suggestions in some prior studies, where grammar disappears, the authors suggest that affect remains within the grammatical structures for polar questions and also statements in KRSL. Wh-questions did not show this differentiation in the average eyebrow movement in sentences, but the authors do acknowledge without a sentence contour analysis this is a matter for future linguistic research. With their frame by frame readings, the data may yet reveal a distinction, as previously found in other signed language research as cited here.

Also, native Deaf signers provided more authentic data than the hearing group, which is not surprising, and in fact is the only data most, if not all, researchers consider.

This is a great addition to the understanding across signed languages, with implications for considering what may be universal and what may be language specific when emotion and grammar interact.

Reviewer #3: The work reported in this manuscript is well motivated, it addresses an important question regarding interaction of affective and linguistic facial expressions during sign language production. Unlike two similar previous studies (De Vos et al. (2009) and Weast (2011), the authors of this manuscript tracked and analyzed subjects’ eyebrow movements during sign production with OpenPose software, which allowed for more precise quantitative and statistical comparisons. Overall, I found this paper to be clearly written. The motivation for the study is well outlined and the results are clearly interpreted.

Only a few minor points:

1. The number of subjects (9) in the study is very small to make some generalizations based on the statistical findings presented in the manuscript; however, the study design and methodology are solid. Given that the authors have explicitly acknowledged some important caveats in their conclusion, the editor may want to consider the manuscript seriously despite a small sample size.

2. Pg 8, Line 328. The number of measurements should be 810. If some measurements were excluded then the authors should state reasons for those exclusions.

3. The authors should include an image in the manuscript (or a video in the supplemental materials) showing how well the OpenPose software tracks the eyebrow movements.

4. For all figures, align the emotion labels to the eyebrows. Some labels were off to one side or another.

5. Did authors analyze left / right asymmetry in the eyebrow positions, particularly for the polar question across the groups? The figure 2 (Hearing signers) seems to show a right-toward asymmetry in the eyebrow position for polar questions, whereas figure 3 (Deaf signers) shows the asymmetry in the opposite direction.

6. Since all signers were instructed to repeat signing a combination of sentence type and emotion 10 times for 9 different combinations. Were those combinations counterbalanced across signers to ensure that the eyebrow positions for some combinations were not affected by fatigue?

7. Have the authors considered the possibility that having an extra person (three as opposed to two) in the room during filming resulted into reduced eyebrow movements for Deaf signers? Or that the hearing signers are more comfortable expressing constructed “anger” emotion due to their experience as interpreters?

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Reviewer #1: Yes: Connie de Vos

Reviewer #2: Yes: Traci Weast, Ph.D.

Reviewer #3: No

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Eyebrow position in grammatical and emotional expressions in Kazakh-Russian Sign Language: A quantitative study

PONE-D-20-02249R1

Dear Dr. Kimmelman,

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

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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With kind regards,

Matthew L. Hall, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Dear Dr. Kimmelman and colleagues - I appreciate your attentiveness to the suggestions for improvement, and the transparency with which you have reported the new analysis. I am very pleased to inform you that after reviewing the changes that you made to the original manuscript in light of the reviewers' comments, I have determined that the manuscript is acceptable for publication, and I thank you for your patience with this process.

Reviewers' comments: The revisions were sufficiently clear that no further review was necessary.