PONE-D-22-11734The social learning and development of intra- and inter-ethnic sharing norms in the Congo Basin: A registered report protocol PLOS ONE

Dear Dr. Lew-Levy,

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Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

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2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Yes

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3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Reviewer #1: Yes

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4. Have the authors described where all data underlying the findings will be made available when the study is complete?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception, at the time of publication. 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

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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

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

You may also provide optional suggestions and comments to authors that they might find helpful in planning their study.

(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: First, I'm really excited to see how this project turns out. It *needs* to be done, and this is the right team to do it. I have numerous compliments for this registered report:

- The introduction was excellent -- well-researched, thorough, and fun to read (I learned a lot about the study site!). I hope to see it again in the eventual publication.

- The team paid thorough attention to exclusion criteria and sample size. Their use of video cameras as backups is important.

- The method they're using for the Dictator Game was adopted from team member House's lead-authored paper (2013) -- the asocial condition from that paper worked well with a neighboring population (and many other populations, across ages, around the globe).

- Their comprehension checks are extremely clear and should be very straightforward for shy participants.

- This is a perfect use of logistic regression (have I ever seen better?) and the team made a clear commitment to a "significance" level of 0.7 (and while the rationale for that threshold is not given, I trust them to have picked a reasonable threshold given their expertise).

I have one larger suggestion/food-for-thought and some smaller ones:

- In this RR at least, the team appears to be giving far more brain time (if reflected by space used in the RR) to the DG relative to the interview. Given the team makeup, I'm sure they'll make good use of their opportunities in the field, but just in case this slipped under the radar, here's what I'm noticing: The team flagged the comparative dearth of ethnographic data on Bandongo social learning of sharing norms, but hasn't laid out any plans to remedy the situation. This seems important because the DG can only take us so far, telling us the timing of when a specific kind of sharing is acquired -- not trade, for example, and not multi-recipient sharing of parts of a carcass, but just division of a windfall between two people. While the team plans to learn how and from whom intragroup and intergroup sharing is learned, they're leaning hard on quantitative measures that work well with a Fisher's exact test. Ethnographic richness, including free responses from less-shy participants, could add ethnographic richness and help the researchers really understand the nature and life-course of norm acquisition. They could ask questions like:

-- In what context are norms acquired, for example? [Observation can happen in myriad places]

-- What does interethnic sharing mean to you? [...just to examine whether the researcher's interpretation of their observations of interethnic sharing matches what participants think are going on.]

-- Are kids learning differently today than they did in the past? And...

-- Are interethnic interactions between BaYaka and Bandongo *different* today than they were in the past? [Secular trends could be sliding past the researchers that would be informative to any differences between kids and adults.]

...of course this, and what I'm about to suggest below, could be difficult to pull off given the team is relying on research assistants, in which case these may be moot points.

- Relatedly, assuming child participants aren't *too* shy and just really want to get out of the research house after the DG wraps up, the researchers could think more about how to get broadly useful data from the post-game interview. For example, other yes/no questions the children could answer that could again add to ethnographic richness are things like:

-- Did you learn interethnic sharing from your mom?

-- Does interethnic sharing mean X to you?

...things that (in addition to their ethnographic observations) allow the team to check whether kids are learning in the same way as adults report *they* learned in the past in the interview -- again, thinking about secular trends and changes in intergroup interaction over time.

- This is a tall ask, and I don't expect the team to necessarily address it, but at least to think about it if they haven't already. The team is attending to things like participant shyness and mobility that might affect sample size. What about self-selection in this regard -- is there any reason to think that candidate participants who acquired interethnic norms earlier, through a different means, or (per my suggestions above) even have a different *set* of interethnic norms would be more mobile or less shy? This is what I would expect a priori, and I wonder if the researchers have any insight into whether self-selection on these lines (or others) would affect their results.

- Sample size will be sufficient if a few conditions hold: the transition from infant to adult state isn't very fast and/or the difference between intergroup and intragroup norm acquisition is four years. Four years is a while developmentally. Do the researchers have any thoughts on how to disambiguate between a quick transition vs similarity in timing of acquisition if results are inconclusive? For example, per the above, it seems that ethnography could really be an asset in that circumstance, including adult's interview responses about when they learned the relevant norms.

- Just to flag this: the team mentions ethnic markers at the outset and never addresses how markers come into play (or not) in BaYaka and Bandongo interactions, but implicitly leans on ethnic markers in the game design, treating red as one ethnic group and blue as another. Presumably markers are salient to BaYaka and Bandongo participants, as they seem to be (in some form or another) to all humans, but establishing this might check the ecological validity of the game (although I'm fine with the assumption that humans everywhere can work with this -- again, just flagging the assumption).

- At one point, the authors end a paragraph about intergroup interactions in children by saying "Inter-group cooperation may be enhanced in communities where strong social norms regulate inter-ethnic interactions" but don't provide citations. When the time comes, they can use two they already have -- Fearon & Laitin, and Bunce (although the 2018 Bunce paper may be better) -- and can also consider any paper about how religion sets norms for intergroup interactions (e.g., Islam in East Africa is a classic -- see Ensminger 1992 Making a Market) and some classic stuff by Barth (e.g., Barth 1956 Ecologic Relationships of Ethnic Groups in Swat, North Pakistan).

- Something to consider: the lag time between research assistant training and project commencement is a bit long (six months-ish). I get the sense that the team does this all the time, so I'm sure they know the best way to go about this, but a refresher for the RAs could be useful before things get started in early 2023.

All in all, again, a well-constructed team doing a project that very much needs to be done, with many laudable things in the RR. I look forward to reading and citing the end product!

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Reviewer #1: No

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The social learning and development of intra- and inter-ethnic sharing norms in the Congo Basin: A registered report protocol

PONE-D-22-11734R1

Dear Dr. Lew-Levy,

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.

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Kind regards,

Mark Nielsen, Ph.D.

Academic Editor

PLOS ONE

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does the manuscript provide a valid rationale for the proposed study, with clearly identified and justified research questions?

The research question outlined is expected to address a valid academic problem or topic and contribute to the base of knowledge in the field.

Reviewer #1: Yes

**********

2. Is the protocol technically sound and planned in a manner that will lead to a meaningful outcome and allow testing the stated hypotheses?

The manuscript should describe the methods in sufficient detail to prevent undisclosed flexibility in the experimental procedure or analysis pipeline, including sufficient outcome-neutral conditions (e.g. necessary controls, absence of floor or ceiling effects) to test the proposed hypotheses and a statistical power analysis where applicable. As there may be aspects of the methodology and analysis which can only be refined once the work is undertaken, authors should outline potential assumptions and explicitly describe what aspects of the proposed analyses, if any, are exploratory.

Reviewer #1: Yes

**********

3. Is the methodology feasible and described in sufficient detail to allow the work to be replicable?

Reviewer #1: Yes

**********

4. Have the authors described where all data underlying the findings will be made available when the study is complete?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception, at the time of publication. 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

**********

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

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above and, if applicable, provide comments about issues authors must address before this protocol can be accepted for publication. You may also include additional comments for the author, including concerns about research or publication ethics.

You may also provide optional suggestions and comments to authors that they might find helpful in planning their study.

(Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Bravo again to this team! I already thought this was a great registered report -- well thought-out and careful -- so I largely left food for thought for the researchers. They took the food-for-thought seriously and came back with an even more detailed, even more well-thought-out RR. I recommend acceptance -- and really look forward to seeing the products of the project.

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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: Yes: Anne Pisor

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