Julien Lie-Panis

My very first paper has just been published in Nature Human Behaviour!

In it, we demonstrate that both a chatbot and a more traditional pedagogical intervention can help improve adolescents' knowledge of vaccines and their attitudes towards vaccination.

Ever wanted to read about an old problem almost nobody cares about anymore?

Well, I wrote about it.

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#HBES2026 abstract submissions are live! More exciting details to come soon.

Arrive early for @ces2026.bsky.social

@humbehevosoc.bsky.social

Research Fellowships Each year, IAST invites applications for post-doctoral Research Fellowships, which offer candidates an opportunity to devote themselves full-time to their research at the start of their careers. Fello...

📢 Apply to our (2-year) research fellowships at @iast.fr

Join a multidisciplinary, interdisciplinary, transdisciplinary, and indisciplinary group of scholars in Toulouse, walkable/cyclable pink city of chocolatines in the South of France.

Deadline: November 15, 2025.

www.iast.fr/research-fel...

Morality Is in Our Brain, in Our Genes, and Even in the Structure of the Universe In defense of "Natural Law", Nicholas Baumard explains how modern scientific understanding of evolution actually supports the idea of a moral sense.

"From this point of view, fairness really may be a universal law."

figure 2 from our preprint, reporting the results from two experiments we measure moral judgments about dividing money between two parties and manipulate the degree of asymmetry in the outside options each party has we find that moral judgments track predictions from rational bargaining models like the nash bargaining solution and the kalai-smorodinsky solution in a negotiation context by contrast, in a donation context, moral intuitions completely reverse, instead tracking redistributive and egalitarian principles preprint link: https://osf.io/preprints/psyarxiv/3uqks_v1

the functional form of moral judgment is (sometimes) the nash bargaining solution

new preprint👇

Summary of design and results from our three studies. (A: Design) Each study used a similar experimental design, measuring both positive and negative demand in an online experiment, with three commonly-used task types (dictator game, vignette, intervention). Our experiments had ns ≈ 250 per cell. (B: Results) Observed demand effects were statistically indistinguishable from zero. The plot shows means and 95% confidence intervals for standardized mean differences derived from frequentist analyses of each experiment and an inverse variance-weighted fixed-effect estimator pooling all experiments (solid bars). Prior measurements of experimenter demand from a previous dictator game experiment (de Quidt et al., 2018; standardized mean difference from regression coefficient) and a meta-analysis primarily including small-sample, in-person studies (Coles et al., 2025; Hedge’s g statistic) are also shown for comparison (striped bars). The main text includes Bayesian analyses that quantify our uncertainty.

We often hear from reviewers: "what about demand effects?" So we developed a method to eliminate them. Something weird happened during testing: We couldn’t detect demand effects in the first place! (1/8)

A randomized controlled trial on the effect of administrative burden and information costs on social inequalities in early childcare access in France Nature Human Behaviour - This RCT finds that providing information and support to target cognitive and behavioural barriers eliminates early childcare application gaps for low-income and immigrant...

1/ Thrilled to share that my main PhD article has just been published in Nature Human Behaviour! 🎉

👉 “A randomised controlled trial on the effect of administrative burden and information costs on social inequalities in early childcare access in France” rdcu.be/eFAEA

I'm giving a free book talk next Wednesday at the Harvard Museum of Natural History. Come by if you're in the Boston area!

👏 Huge congrats to @audeber.bsky.social, group leader and head of our Molecular Diversity of Microbes lab, on being named a 2025 Vallee Scholar! Her pioneering work on ancestral immunity opens new perspectives for biomedical innovation. 🔬🌍

@valleefoundation.bsky.social

#Science #Immunity

Why do societies reliably develop strikingly similar traditions like dance songs, hero stories, shamanism & justice institutions?

In a new BBS target article, I propose a theory for such "super-attractors" + cultural evolution more broadly. Now open for commentary: www.cambridge.org/core/journal...

YouTube video by Evolutionary Psychology (The Podcast) Cooperation with Pat Barclay

This week, we discuss the evolution of cooperation with Pat Barclay.

youtu.be/-cHqagwF1yY?...

podcasts.apple.com/us/podcast/e...

www.podbean.com/eas/pb-f5gtf...

Very excited to see this published!

Evolving general cooperation with a Bayesian theory of mind | PNAS Theories of the evolution of cooperation through reciprocity explain how unrelated self-interested individuals can accomplish more together than th...

Our new paper is out in PNAS: "Evolving general cooperation with a Bayesian theory of mind"!

Humans are the ultimate cooperators. We coordinate on a scale and scope no other species (nor AI) can match. What makes this possible? 🧵

www.pnas.org/doi/10.1073/...

Contractualist Moral Cognition: From the Normative to the Descriptive at Three Levels of Analysis Visual summary of the paper. Taking inspiration from the contractualist tradition in moral philosophy is helpful to better understand morality at three interrelated levels of analysis: Its evolutiona...

Arthur has written a wonderful, clear, super helpful introduction to contractualism as a foundation for moral psychology. Perfect for getting up to speed, teaching, a desk reference, or a sunny day at the beach. wires.onlinelibrary.wiley.com/doi/10.1002/...

So pleased to have won this award. Thank you @ceciliapad.bsky.social @gregoryfiorio.bsky.social @ruthmace.bsky.social @humbehevosoc.bsky.social

Our paper on the logic of guesses is now out!

We provide a new information-theoretic perspective on many phenomena (old and new) in judgment under uncertainty.
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🚨 Now out in Nature Human Behaviour 🚨

We show that following the news on WhatsApp or Instagram (N = 3,395 🇫🇷🇩🇪) increases current affairs knowledge, participants’ ability to discern true from false news stories, awareness of true news stories, as well as trust in the news.

doi.org/10.1038/s415...

The winners of the HBES Margo Wilson Award (best paper in E&HB the previous year) are Olympia Campbell, Cecilia Padilla-Iglesias, Gregory Fiorio, & Ruth Mace for the paper “Genetic markers of cousin marriage and honour cultures”. Congratulations!
doi.org/10.1016/j.ev...

#HBES2026 will be a joint meeting with the Cultural Evolution Society in Rabat, Morocco: CES is May 11-13, HBES is May 13-16, with one day of planned overlap. It’ll be a great chance for cross-pollination between the two evolutionary societies. Come for one conference, stay for both!

We often have to judge who is knowledgeable—precisely when we are not. Can humans really do that? Our new paper in Psychological Science shows that, surprisingly, we can. drive.google.com/file/d/1b15E...

This is a great opportunity to work with @yohm.bsky.social, one of the leading researchers in evolutionary game theory these days. 🙂
I can only recommend applying ⬇️

An incredible opportunity! 📰🎉 Join our research group exploring social questions, work with an amazing supervisor, and live in Japan for a few years while you're at it! 🇯🇵🍜

Seeking a few Research Scientists or Postdoctoral Researchers at Mathematical Social Science Team (W25015)

📢 We’re hiring! RIKEN iTHEMS has launched a new Mathematical Social Science Team, and we’re looking for researchers to join us. If you're into cooperation, norms, or networks, check out the call!
🔗 www.riken.jp/en/careers/r...
Feel free to DM me if you have questions!

Out today!

📢 Research Assistant (Quant Soc/Data Science) – 4-month full-time contract
Join an interdisciplinary project @cris-sciencespo.bsky.social on reducing early childhood inequalities. 🤩
📍 Paris
🗓️ Sept–Dec 2025
💰 ~€2500/month + benefits
Apply by June 15! More details 🔽
drive.google.com/file/d/1_mQH...

🎙️We’re thrilled to introduce our #ZPLS Keynote Speaker: @sachaltay.bsky.social! Join us as he presents “Rethinking the Problem of Misinformation” — a fresh perspective at the intersection of Psychology and Law, on May 22nd‼️registration: celleuven.wixsite.com/home/zpls/z-...

Excited to speak about some new work on Bayesian Cooperation at this workshop! Join us virtually

Dystopia is closer than you think We take our usual way of life too much for granted

We easily take the way our society works for granted. However, it only relies on what's in our minds: our shared expectations about each other's behaviour.

What’s happening in the US illustrates how the norms on which social order rests can erode and break down.

Harmless bodily pleasures are moralized because they are perceived as reducing self-control and cooperativeness Why do many people morally condemn unrestrained indulgence in bodily pleasures—such as gluttony, masturbation, and drinking alcohol—even when these be…

New paper from @lfitouchi.bsky.social:
Why do people moralize harmless bodily pleasures?
www.sciencedirect.com/science/arti...