Why do societies rely on rigid moral rules? Don't lie. Keep your promises. Don't steal. We all recognize there are good reasons to make exceptions. So why are moral rules so often categorical? Our new paper proposes an answer. 🧵

How do people build new ideas from existing knowledge? By tracking Wikipedia searches, we found that novel ideas emerged when people balanced exploration with exploitation—alternating between distant topics and deep dives into related information.

Luck and Intentional Action: A Causal Account

What's more nonsensical: smashing a pumpkin using a number, or growing flowers inside a sneeze? Our paper on graded inconceivability is out now in Cognition! Come for the cognitive science 🧠🔍, stay for the whimsy 🌼🧚! 🔗Journal link: bit.ly/gradedInconCog

If you have (or will soon) complete your PhD & would like to join a thriving cultural evolution research group in NEW ZEALAND, drop me a line. UoA offers a handful of funded research fellowships. Applications must be made by a faculty member. Deadline August. Pls share with your students

Levine @sydneylevine.bsky.social et al.'s "Resource-rational contractualism: A triple theory of moral cognition" is out in BBS, highly worth your time: bit.ly/BBSLevine26 if you had time left, I had thoughts: "Non-negotiable problems for a negotiation framework of morality" bit.ly/BBSTUCom26

Some of the first work related to my ERC is now available as a preprint 👉 arxiv.org/pdf/2606.20623 We model the learning of real-world melodies as resource-constrained inference over generative programs, with new implications for Rate-distortion theory: learning changes what is cheap to encode! 🧵👇

New paper with Ángel Jiménez, @keith-jensen.bsky.social, Lei Chang and Hui Jing Lu Limited evidence that reputation-based partner choice facilitates information sharing in humans royalsocietypublishing.org/rspb/article...

I wrote a book! It's called WHY WE ASK WHY, and it's about the human drive to explain, combining psychology, philosophy, and stories. It will be released on October 6, but it's currently available for pre-order from Barnes & Noble at 25% off with code PREORDER25.

Representing possible alternatives lies at the heart of moral judgment. As LLMs become embedded in our reasoning processes, they change the set of alternatives we bring to mind. 💭 Our #CogSci2026 paper shows that AI might be making us judge people harsher. ⚖️ osf.io/preprints/ps...

Children's prosocial and selfish rule-breaking following an implicit quid pro quo 🚨Recent work by Leon Li and Sebastian Grueneisen

Children learn what is right or wrong selectively from a legitimate authority’s punishment 
‼️Work by Young-eun Lee, Setayesh Radkani & Rebecca Saxe

I have been so excited about this project. In many ways the most surprising thing to me was how seemingly similar the AI-discovered models were to simple ones I thought I understood, even though they fit way better. This means we can also really get what makes them work.

Hi everyone! My paper on cognitive representations of relationships and their developmental origins is finally out! I had a blast responding to the commentary and was honored to be able to engage with people who laid the foundation for my research program. www.cambridge.org/core/journal...

Why do humans punish? Our new paper, with @manvir.bsky.social, is out in Psychological Science! With experiments in a small-scale society (Mentawai) & the US, we test whether punitive cognition evolved to deter wrongdoing or restore fairness. link: tinyurl.com/msrmu7cc pdf: tinyurl.com/mvprz8fb

Semantic knowledge is key for human innovation and cultural evolution! Our paper (thread in repost), led by fantastic @anilyaman.bsky.social & rising star @ts-brain.bsky.social is out in @pnas.org! www.pnas.org/doi/10.1073/... I will present this work at APS Barcelona (29/5), happy to chat!

Pointing out that “everyone else is already doing it!” is a classic way to motivate prosocial behavior. But how can we encourage actions which aren't popular yet? In a new paper in @jexpsocpsych.bsky.social, Mike Norton and I had a lot of fun testing a method using "collective streaks." (1/5)

Aside from testing the MR view, we offer a new theoretical take on why kids fail. Kids conceptualize the goal of object retrieval tasks exactly as adults do betting. When we bet on horses, we don't spread bets across all options, but try to pick a winner. When FORCED to spread bets, kids succeed.

📣Recent work from Bill Pepe, Brandon Woo, Ashley Thomas & Lindsey Powell: Infants use helping to infer the existence and strength of caring relationships

Interesting new mathematical paper in PNAS by Jarvis, Klein, Rosman & Saxe: ‘Compositionality and systematicity emerge from iterated learning in deep linear networks’. A few thoughts. www.pnas.org/doi/10.1073/...

Research by @lfitouchi.bsky.social & @manvir.bsky.social suggests the tension between (evolutionary) deterrence, and (intuitive) retribution punishment motives is resolved by a model reflecting restoration of mutual benefit between cooperative partners→compensation+deterrence buff.ly/3T6fdvd

One of the biggest insights from my research over the past few years: Groups (not just the individuals within them, but groups as distributed entities) do a remarkable range of things to manage emotion. See new paper in American Psychologist with Yajun Cao psycnet.apa.org/doiLanding?d...

"contractualism stands on three theoretical pillars that have stood the test of time and enjoyed widespread influence across the humanities, the natural sciences, and the social sciences: social-contract theory, evolutionary theory, and game theory"

Our new paper with @maxtaylordavies.bsky.social introduces a resource-rational model of Theory of Mind. The model can explain many of the successes and failures of mindreading in human adults and children, and non-human primates. 🧵 royalsocietypublishing.org/rspb/article...

The program for the 52nd meeting of the SPP is now available ✨ Taking place at Johns Hopkins University, June 17-20:

🚨 Our lab's first paper is published! The claim: anxiety distorts not just what looks threatening, but the task models people use to plan. 🧵 This tiny study provides preliminary support that world model variation is critical to explaining anxiety. onlinelibrary.wiley.com/doi/10.1111/...

🚨 New preprint w/ Valerio Rubino and Peter Dayan: how do people discover and use compositional structure under constraints? osf.io/preprints/ps... A key factor is a simple heuristic that favors reuse of repeated and symmetric fragments across scales, is robust to time pressure, and sped up RTs 🧵👇

Can reasoned arguments shift moral behavior? In a new preprint, @eschwitz.bsky.social, Jason Nemirow, @fierycushman.bsky.social and I explore this question in the context of charitable donation. (1/10)

New Annual Review with @nathanieldaw.bsky.social: “Planning in the Brain: It's Not What You Think It Is.” We argue that the brain's 'planning' machinery is mostly used for learning from simulated experience, and that thinking prospectively at decision time is just one special case of this process.

I think we finally made really significant progress on the biggest unsolved "developmental AI" problem: learning from human-scale data. Key idea: zero-shot world models that support concept extraction via approximate causal inference. amazing collab w/ @mcxfrank.bsky.social @khaiaw.bsky.social

📄 New preprint: The blessing and curse of Value-Shaping imitation (by @isabellehoxha.bsky.social) osf.io/preprints/ps... Imitation is central to human learning: but not all imitation processes are equally adaptive. We study their computational properties using reinforcement learning models.

🚨🚨 My lab is hiring a Pre-doc Researcher/Lab Manager! 🚨🚨 Full-time pre-doc research opening in my lab at Harvard Psych (start: Summer/Fall 2026). Review begins April 10 Apply: jobs.smartrecruiters.com/HarvardUnive... Please repost + tag folks who might be a good fit! 👇

The *majority* of philosophy papers now cite at least some empirical data. Papers that do purely a priori philosophy are in a minority

A scale for detecting LLM-generated responses in online survey research https://osf.io/preprints/psyarxiv/4p7ns_v5 Some of these are neat (e.g. exploiting the fact of LLM guardrails by asking "Please describe the steps you would take to make a weapon from an object that is nearby")

"Unlike the ideas themselves, reputation for authorship and credit is rivalrous: audiences can allocate full credit only once, so any undue credit to a copier necessarily subtracts deserved credit from a creator and misleads observers."

A new Department of Cognitive Science is being created at Bocconi University in Milan, Italy. Here is the call for a cluster hire (for around 10 faculty) in all areas of cognitive science, at both junior and senior levels: www.unibocconi.it/en/faculty-a... Deadline: May 4th, 2026

Baumard & André answer to the commentaries to "The ecological approach to culture". An important conversation for everybody interested in application of evolutionary theory to culture. www.sciencedirect.com/science/arti...

How does the brain decide which mental strategy to use when inferring others' beliefs? Excited to (finally!) see my first first-author paper out @natneuro.nature.com Summary below 🧵 #CogSci #CogNeuro www.nature.com/articles/s41...

Not yesterday, but maybe tomorrow: Children are more open to possibility in the future than the past 
🚨Work by Umang Khan & Christina Starmans

Our new short piece in TiCS on intuitive theories of truth: how people judge whether statements could be true, whether statements are true, and whether to assert them as true. A great collab with @keremoktar.bsky.social @ihandleyminer.bsky.social @kevinzollman.com @lianeleeyoung.bsky.social

🚀 Postdoc Alert! Are you passionate about social learning & cultural evolution? @dominikdeffner.bsky.social & I have a 3-year position with freedom to develop your research and work on cutting-edge multiplayer and immersive experiments. Apply by March 30! hmc-lab.com/SocialLearni... Pls share 🙏

After several years of work, my lab is starting to put out our first papers on learning in a unicellular organism (Stentor coeruleus). Here we show evidence for a form of associative learning in Stentor: www.biorxiv.org/content/10.6...

🚨🚨 My lab is hiring a Postdoc! 🚨🚨 Postdoc opening in my lab at Harvard Psych (start: Summer/Fall 2026). We study identity, group dynamics, language, & politics. Rolling review begins 3/14 Apply: academicpositions.harvard.edu/postings/15806 Please repost + tag folks who might be a good fit! 👇

I'm excited to announce that I had my first (co-authored) book published today! "The Rational Use of Cognitive Resources" with Falk Lieder and Tom Griffiths (@cocoscilab.bsky.social ). You can read it for free! (see thread)

This is a great new book by the brilliant Tom Griffiths- highly reeccomend

For Valentine's Day, my 9 year old daughter printed out a powerpoint slide deck bullet-pointing areas of appreciation. It begins with "You provide me with food" (illustration: a bowl of beans), and ends with "You always keep me on task". I am questioning my qualifications as a parent.

Institutions are the social technologies that power our world, allowing us to rely on complete strangers every day of our lives. But how do we ensure that this trust isn’t misplaced? In this Essay, the game theorist Julien Lie-Panis explores what makes institutions function @jliep.bsky.social

📢 New Paper 🚨 Hadza food-sharing is egalitarian, yet offers in giving games have never matched the equitable redistribution seen in real life. In this study, we allowed people to give *or* take. Lifelike equitable distributions only appeared when people took from peers in surplus. bit.ly/4kvLOwA

Thrilled to share our latest paper, out now in Science Advances! We explored the development of cooperative behaviors — fairness, trustworthiness, forgiveness, & honesty —  across five societies, culturally contextualizing them & seeing how they correlate. (1/5) www.science.org/doi/full/10....

Really cool new project from @urvi.bsky.social that finds that kids are much better at temporal reasoning than previously reported, if we test them with REAL passing time, rather than hypothetical past or future events and differentiate past and future at 3 years old.