PONE-D-22-12946A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX)PLOS ONE

Dear Dr. Wood,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jul 29 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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Arezoo Eshraghi, Ph.D.

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

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

Reviewer #1: I Don't Know

Reviewer #2: I Don't Know

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

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: This study outlines the development and validation of a way of measuring workload specific to prosthetic use. Technically, the methods are sound. However, there are some concerns.

First, in the survey of prosthetic limb users, there are some large limitations in the sampling. I understand that the sample size is similar to previous research, but you should still commend on the small sample size for determining a validated outcome measure and how representative it is of the wide population. It seems to be skewed to include a disproportionally high number of myoelectric users over body-powered device users, unless you are aiming for it just to be representative of myoelectric users. Also, please specify what level of amputations your participants had – if your sample includes both individuals with transradial and transhumeral amputations, the workload, their responses to the questions, and the reduction in the responses over time may be vastly different. It is likely not appropriate to combine them. In addition, it is even more concerning that most of the questions are about first learning to use your hand, however, the respondents had a mean of 15 years wearing a prosthesis, which is far removed from first learning to use it. I do not think this this sample is appropriate for what you are asking.

Regarding the survey questions to this group, can you please provide some more information. 1) Please explain why you grouped concentration and mental fatigue together. 2) Please explain how much each of the domains decreased. You stated that mental demands decreased 100%, but by how much? 1 point on the Likert scale? 4 points?

Regarding the development of the measure itself, I can see it’s usefulness and it seems to follow a logical development.

I am unable to comment in detail on the suitability of the statistics.

My second concern is on the appropriateness of the discussion and conclusion. The limitation of validating a prosthesis workload questionnaire on able bodied participants is that the workload of using your anatomical hand is very low and the workload of using a brand new prosthesis device is very high. Saying that the PROS-TLX is sensitive enough to measure the different is not a strong statement as one would expect these two things to be extraordinarily different. If you want to comment on the sensitivity of the measure, I suggest measuring two more similar situations (between myo and body powered, between a basic myo hand and a multiarticulated one, etc.). It is also weak to use a lower extremity example in stating the clinical application of this measure for a prothesis user and imprudent to say you are confident that it is representative of lower extremity mental workload too. The entire paper is focused on upper extremity and there is no mention of any lower extremity application until the takeaway message.

Also, it is true – you have validated this measure in able-bodied participants and it is not representative of the clinical population. One might agree that it is relevant in the first 10 minutes of using a prosthesis for the first time, but after that it becomes irrelevant. This is a huge limitation and should be discussed as such. In many studies, I see the protocol piloted on able-bodied participants and then more thoroughly evaluated on people with amputations. I would strongly recommend evaluating this measure using actual prosthesis users.

My only other comments would be about some questions in your abstract and introduction. Please clarify. 1) Does it requires emotional effort to use a prosthesis? 2) Why is using a prosthetic limb difficult? 3) Why is it clinically relevant to understand prosthesis workload? 4) Has the NASA-TLX ever been validates for use with prosthesis users?

You did a great job explaining different ways of measuring workload, their limitations, and why they are not clinically useful. I see the need for this measure and think it will be useful. I am concerned that it was formed and validated on a population that is not transferrable to the clinical environment.

Reviewer #2: Major:

Strengths:

• The manuscript is well written and easy to follow.

• The need for the work is well justified.

• The potential significance is high as this work aims address a need to develop and validate a self-report measure of mental workload specific to prosthesis use.

• The approach taken mirrored the development of methods used in two other areas for modification of the TLX.

• Surveys and responses available on the Open Science Framework make the data and analysis available to other researchers.

• It was good to eliminate non-applicable constructs (e.g., social stress) from the measure based on the user responses.

• Exploring multiple metrics (e.g., functional task, eye tracking, etc.) improve the significance of the work.

• Convergent and divergent validity were appropriately established through correlation analyses with RSME and IMI, respectively.

Weaknesses:

• No persons with limb absence were used in the validation of the metric. Therefore, the conclusion that “the PROS-TLX captures the multidimensional nature of the cognitive, physical and emotional workload experienced by prosthesis users and provides……” This is the major reservation of this author to allow it for publication. The validation portion of the study did not use any amputees and therefore the application to the amputee population (which is the point of the work) remains in doubt. The study that is referenced to show equivalence between able-bodied and amputee subjects [28] was done using EEG to control the device, which only tangentially appliable. At a minimum, if the validation testing was completed on a subset of amputees and shown to have similar results to able-bodied subjects, may be acceptable.

• The literature referenced to document the issues experienced by prosthesis users includes only two references and therefore is incomplete.

• While the number of users (8) that were used to confirm the workload dimensions was justified by being similar to a prior study. Just because someone else used that number does not mean that it is an acceptable number and further justification is necessary.

• Of the 8 individuals that were used, 7 of the 8 were myoelectric users and therefore the results are likely cannot be generalized to the body-powered user population. This should be stated as a weakness.

• Limb users were surveyed to confirm the importance of constructs that were taken from literature and prior measures, but were not engaged to include/develop constructs that were likely not have captured through these other mechanisms.

• There is a large concern that the validation study used only the coin task of the SHAP with a multi-articulating prosthetic hand. Multi-articulating hands are particularly poor at picking up small objects (as compared to gripper terminal devices or body powered prostheses) and therefore this is a highly frustrating task that is not representative of most of the tasks that are done with a prosthesis. This is especially true for unilateral amputees that will likely just complete the coin task with their intact hand. Other bi-manual tasks would be informative.

• The SHAP is specifically designed as a timed test, not to be performed at a natural speed. How can you know if subjects where subjects were placing their priorities for completing the task (speed vs. drops) in the pressure condition? These are obviously conflicting demands. Also, if they were told not to rush during the non-pressure condition, should time be compared during non-pressure conditions?

• Why were subjects asked to complete the Part 2 comparisons ‘from using the prosthesis in general rather than in any one condition’? The only condition they had used it in was the coins task and, since they are not prosthesis users, didn’t have any other usage to compare against. Also, these comparisons of weights do not appear to have been presented in the results.

• Since time pressure did not show a significant increase in workload scores, shouldn’t it be removed from the PROS-TLX?

• It is likely an overstatement to claim that the PROS-TLX is sensitive enough to measure workload characteristics beyond differences between intact hand and prosthesis use as there was no comparison between two prosthetic interventions that have different mental loads (e.g., 2-site myoelectric control of a hand and wrist vs. pattern recognition control of a hand and wrist).

• The applicability and generalizability to lower limb amputees needs to be removed from the document as no LL amputees or testing with lower limb prostheses was performed in this work. There are already concerns about generalizability to even body powered upper limb amputees, much less lower limb.

Minor:

Weaknesses:

• The Data Availability Statement does not describe where the data can be found.

• The data (at least for the coin drops in Figure 2B) does not appear normally distributed and is identified in the text as non-parametric. Therefore, box plots are a more appropriate way to visualize the data (and not the dot and whisker that is used).

• It is unclear why the questions that were asked of the amputee users (Page 12-13) ask about ‘first learning,’ ‘learning to use,’ and ‘learning to move.’ Why were different sentence structures used?

• Grouping various constructs under item 5 appears inappropriate. ‘Insecure,’ ‘discouraged,’ ‘stressed,’ ‘irritated,’ and ‘annoyed’ are all very different constructs. (maybe you could claim that irritation and annoyance are similar enough). How are you able to know which of these verbs were the ones that users were focused on when answering the question?

• A similar comment could be made for items 6 & 7, but the difference between ‘anxious’ and ‘stressed,’ and ‘hurried’ or ‘rushed’ is less severe.

• Please clarify on page 15 (of the PDF) that the hand is controlled by ‘isometric’ muscular contractions.

• Please describe why ECR and FCR muscles were chosen as opposed to EDC, ECU, FCU, finger flexors, etc. The proximity to the brachioradialis that will be active supporting the weight of the simulated prosthesis could create crosstalk with the radialis muscles. Also, please describe in more detail the methods used to locate and identify these muscles.

• Page 17, describes ‘After completing each task,’ but there was only one task (coin task), correct? Please clarify.

• Does the 20-point Likert scale match the NASA-TLX?

• Please provide more details on how the 28 pairwise comparisons between dimensions were administered in the text and results. I looked on the link provided on page 17 of the PDF but did not see them there and they are not discussed in the analysis.

• Please provide a brief description of Conover comparisons are as they are not a commonly utilized metric as compared to other approaches and it is likely that readers (like this reviewer ) will be unfamiliar with them.

• The bottom of page 23 of the PDF states: Analysis of the relationships between PROS-TLX constructs showed moderate to strong correlations between almost all PROS-TLX dimensions and every dimension correlated with total workload score, as expected (see Figure 4). However, correlations b/t each of the PROS-TLX and total workload score are not presented here, they are only correlated to Performance time, coin drops and hand fixation rate. It may be that the captions and references to Figure 4 and Figure 5 are switched in some places. This would be true if the caption for figure 5 removed the reference to ‘total workload’ and replaced it with ‘hand fixation rate.’

• In the discussion, can you clarify why, if the goal of the study is to design a self report measure of mental workload, why physical demands are included in the analysis. Is there evidence that these two are linked as they seem to be very different constructs?

• Please provide a more detailed description of the main paragraph of page 26 of the PDF. The data from figure 4 shows that, while significant, the correlation between hand fixation rate and the visual demands question are only 0.2, vs. much higher correlations between other factors and measures.

• References listed for background literature used in the development of the measure was listed as [5,18] earlier in the manuscript and then [6,19] and [18] in the discussion. Please clarify which is correct and make them consistent.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-22-12946R1A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX)PLOS ONE

Dear Dr. Wood,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Dec 25 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Jerritta Selvaraj

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

**********

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

Reviewer #1: I Don't Know

Reviewer #2: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. 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: Thank you for responding to the comments. Your responses helped to clarify several things. However, I think there are still some weaknesses that need to be addressed.

- In the abstract, what is your rationale for saying that when using a prosthesis, a high level of emotional effort is experienced?

- Also, in the abstract, you need to include that this paper focused on upper extremity. While you have commented on its applicability to lower extremity in the future, this paper simple did not do that, and you need to provide this specific information to your readers. This is also true in the background. You need to explicitly state that you are hoping that this measure will be applicable to both upper and lower extremity prosthesis users, but in this study, you are specifically looking at upper extremity.

- You are still missing basic demographic information about the individuals who completed your survey including level of amputation.

- These are still large issues in your methods. You stated, “The goal of the study was to understand, from the experience of prosthesis users, what factors contributed to experienced workload when first learning to use the hand, and also how each of these factors changed over time”. You are asking questions that, while they are answering, are likely not accurate responses. I appreciate that you were using these individuals to confirm that the items you included were relevant. However, an average of 15 years is too long of a recall period to draw conclusions about learning to use a prosthesis. While no participate may have commented they could not remember, I challenge you to remember the detail of an experience you had 15 years ago. To address this, you need to include a comment on recall bias and address this length of time. There is lot of research on recall and memory. I suggest doing more background reading and commenting on this in depth.

- You mention how you removed the social stress section. Does the social stress of how they are perceived impact their workload and control because more of their brain is dedicated to dwelling on this aspect? This seems to be the closest thing to emotional demand that you mentioned earlier but now you removed it.

- Bringing in lower prosthesis users in the discussion is unnecessary and confusing to the reader (page 21, line 16). It is already concerning you are expanding the application to users with upper extremity prostheses, let along lower extremity ones.

- There are still significant issues with talking about the validation of a measure without using individuals with upper extremity limb loss. Make this abundantly clear in the discussion and results. You have completed step 1, but it is not yet suitable for clinical use. In addition, your results show difference between no prosthesis and a prosthesis but not between prosthesis conditions. The difference between using your hand and using a prosthesis is massive and a measure does not have to be very sensitive to pick this up. There is evidence that this measure is not sensitive enough to compare between conditions in a prosthesis. Therefore, it is likely an overstatement to say that it can be used to understand prosthesis control, test interventions, monitor the nature of the workload experienced and how it changed through rehabilitation, assess developing technologies, etc. While this work has importance, you need to be realistic about stating it’s importance and the further work needed.

Reviewer #2: The authors made changes to address several of the comments that were discussed by the reviewers that have improved the manuscript. They also made reasonable counterarguments in several cases (e.g., regarding sensitivity, potential applicability to non-myo users, justification for 8 subjects due to the goal of their involvement, etc.). However, the changes that were made have not reached the level to make this reviewer willing to suggest that the work is ready for publication.

Overall, there appeared to be a general reluctance by the authors to address the questions/concerns that were shared by both reviewers in the manuscript. In general, even if the authors are correct on a given point, if multiple reviewers have questions/concerns about a given topic, it requires a more detailed explanation and clarification in the manuscript. It is likely that many other readers of the manuscript will likely have less expertise than the reviewers in understanding the concept and therefore more clarification is justified.

For the reasons described above, it is important to include changes in the manuscript to further explain and clarify questions brought up by the reviewers. The authors responses to many these comments was on point, and the manuscript would benefit from the inclusion of these explanations in the final draft. For this reviewer (#2) these include:

o Reasoning/logic behind picking the coin task for the SHAP and how, while the SHAP is typically timed, the authors chose to modify the approach.

o Stressing wording was taken directly from the original NASA-TLX related to insecure/stressed/irritated/stressed/hurried/rushed/etc.

o Description of Conover comparisons

o Description of the inclusion of physical demands

o That the experimental session was only designed to show that the TLX was sensitive to measure changes in different workload constructs and not between different prosthetic interventions.

Comments related to this reviewer’s (#2) responses is below.

Major:

The overall conclusions need to be further softened and the limitations of the study expanded. Every study has its limitations, that is completely acceptable, and the limitations do not all have to try to be justified away. I understand why the authors would prefer to not list out the limitations of the study, but they exist and should be described in detail. I believe that this manuscript is an important first step in the development of the instrument, and it is worthy of publication, but limitations need to be called out with greater emphasis.

For example, please add “the PROS-TLX captures the multidimensional nature of the cognitive, physical and emotional workload experienced by able-bodied prosthesis users using a prosthesis simulator and provides…” Following this with a description of how the able-bodied results may translate to amputee users would be appropriate.

The authors were accurate to correct this reviewer that the study that is used to provide evidence that amputees and non-amputee users of a simulator report similar levels of workload on the NASA-TLX [28] did not use EEG for the control system. However, after further review, it was discovered that this study used only used a single subject (n =1), using a very advanced, implantable control system (and therefore would be argued to not be ‘entirely appropriate’ as stated by the authors). In addition, this study compared the single amputee’s results to two able-bodied subjects, and report that ‘the group was not large enough to draw any statistical conclusions.’ Therefore, equivalence between amputee and able-bodied users cannot be shown by this work. These limitations should be noted.

I think the authors make a good argument that simulators can be shown to be fairly representative of other aspects of actual prosthesis use. While I understand that there are references showing the relative equivalence between AB users using simulators and amputees, the study would undoubtedly be strengthened by performing testing with amputee subjects. I agree with the authors claims that the results are relevant to amputees, but they are not results obtained directly from the population that this metric will be applied to (i.e., amputee users) and this needs to be stressed as a limitation.

There is a bit of a circular argument in the authors’ response that the users were only being used to validate the constructs that were acquired previously from the literature (and therefore the number of subjects that were used was not really all that relevant), but then later describe that input was taken from these users to include additional constructs (e.g., uncertainty). Frankly this reviewer is OK with the process used (the main goal is validation, but you’ll take the additional input when you can get it quickly and easily), but would caution the authors in their selective responses. (No response required).

Please clarify why using the simulator could be considered a strength. Wouldn’t an amputee user be able to have similar comments on the workload they just experienced? What are the limitations that are created by memory recall? Ideally new, amputee subjects would be used here to get the best of both worlds, right?

Further results of the weights that were reported by subjects should be reported in detail. These data would provide useful evidence to other researchers to understand and interpret the work, and potentially apply in their own use.

Unless the normality of the data presented (e.g., in figure 2b) can be shown to have a normal distribution, the presented method of visualization is incorrect and needs to be rectified. The authors state that a box and whiskers would ‘look very clunky.’ This reviewer would find either 1) analyzing and presenting results showing the data are normally distributed or, if not, 2) any way of visualizing the non-normal data that the authors deem visually pleasing, to be acceptable.

Minor:

Regarding muscle location finding:

• By ‘touch’ do you mean ‘palpation’?

• Please remove the sentence, ‘This procedure minimized any cross talk with other muscles’ as this is unlikely to be true given the ECR/FCR proximity to the brachioradialis….frankly it is details like this that add to the reservations about using able-bodied subjects using a simulator and saying they are a suitable stand in for actual amputees using a prosthesis.

In attempting to align reference numbers it appears as thought Reference 9 and 10 do not agree between earlier in the manuscript and in the discussion.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

**********

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PONE-D-22-12946R2A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX)PLOS ONE

Dear Dr. Wood,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by May 07 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Jerritta Selvaraj

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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

Reviewer #1: I Don't Know

Reviewer #2: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

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6. 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: Thank you for addressing most of my previous comments. I still have a few outstanding comments that need to be addressed.

- In the abstract, I still disagree that a high level of emotional effort is experienced when using an upper limb prosthesis. While this may be true for some people, there are many prosthesis users who do not experience high emotional effort (or high physical or mental effort for that matter.). Many users are very comfortable using their prostheses. Please reduce the severity of the descriptor or reword this to be more encompassing of all users of prostheses.

- Also in the abstract, it is still my opinion that you remove “lower-limb amputees” from the further work section. This paper is focused on upper extremity. It is ok to include it in the limitations section of the discussion, but I do not think it belongs in the abstract.

- Also, “upper-limb […] amputee users of prosthetic devices” is not good grammar.

- Page 22 Line 15 “Primarily myoelectric upper limb prosthesis users”

- Page 23 lines 3-10 – And also more work is needed on individuals in rehab actually learning how to use a hand for the first time.

Reviewer #2: Reviewer #2:

Overall, this round of edits was responsive to the primary concerns of this reviewer and, particularly the expansion of the description of the limitations, has substantially increased my level of enthusiasm for publication. With one final, minor edit, I believe this should be in good shape. If the editor is comfortable with the response by the authors to this item, this reviewer does not need to do any additional review on this paper.

• In response to Reviewer #1s comment on level of amputation, the authors claim that they addressed this issue on P22, L11, but I didn’t see it there (or elsewhere).

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

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While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

A tool for measuring mental workload during prosthesis use: The Prosthesis Task Load Index (PROS-TLX)

PONE-D-22-12946R3

Dear Dr. Wood,

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.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Jerritta Selvaraj

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

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

Reviewer #2: I Don't Know

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

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6. 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 #2: N/A..................................................................................................

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

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