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Tom Costello

@tomcostello.bsky.social
3.9K followers 246 following 200 posts

research psychologist. beliefs, AI, computational social science. assistant prof at Carnegie Mellon

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Tom Costello @tomcostello.bsky.social · 29/09/2026
Tomorrow morning in DC I'm moderating a panel on feeds and politics with @cerenbudak.bsky.social, @filipecampante.bsky.social and @ylelkes.bsky.social. Misinformation, politicians writing for the algorithm, why depolarization is so hard, and what changes when people ask gen AI instead.
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Esther Boissin @boissinesther.bsky.social · 21/09/2026
Happy to share a new preprint with @tomcostello.bsky.social, @dgrand.bsky.social and @gordpennycook.bsky.social 🧵 "What beliefs are most debunkable?" osf.io/preprints/ps... We investigate the characteristics of the beliefs that are (or are not) influenced by counterevidence in 3,341 AI dialogues.
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Rafael M Batista @rafmbatista.bsky.social · 10/09/2026
#Debunkbot by @tomcostello.bsky.social for #AISafety debunkbot.com?topic=ai-saf...
debunkbot.com
AI Safety
Ask any question. Get a strong explanation.
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conputer dipshit @davidcrespo.bsky.social · 24/07/2026
counterpoint?
gemini 3.6 answering “do vaccines cause autism?”

No, extensive scientific research has established that vaccines do not cause autism.

The idea originated from a small, now-retracted 1998 study by Andrew Wakefield that claimed a link between the measles, mumps, and rubella (MMR) vaccine and autism. Subsequent investigations revealed that the study contained falsified data and ethical violations, leading to its complete retraction by the journal The Lancet and the revocation of Wakefield's medical license.

Since then, numerous large-scale, rigorous global studies involving millions of children have repeatedly evaluated the MMR vaccine, thimerosal (a preservative formerly used in some vaccines), and the overall vaccine schedule. Major health organizations worldwide—including the World Health Organization, the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the Institute of Medicine—have consistently concluded that there is no evidence linking vaccines or vaccine ingredients to autism spectrum disorder.
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Yamil Ricardo Velez @yamilrvelez.bsky.social · 09/03/2026
Conditionally accepted at the APSR (w/ @scottclifford.bsky.social & @patrickpliu.bsky.social): Why does political information so often change beliefs but NOT attitudes? We highlight the role of belief relevance, or the extent to which beliefs bear on attitudes.
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sjdm-tweets @sjdm-tweets.bsky.social · 05/03/2026
Today's SJDM Featured Paper is: Costello, T. H., Pelrine, K., Kowal, M., Arechar, A. A., Godbout, J.-F., Gleave, A., Rand, D., & Pennycook, G. (2026). Large language models can effectively convince people to believe conspiracies. arXiv. doi.org/10.48550/arX...
doi.org
Large language models can effectively convince people to believe conspiracies
Large language models (LLMs) have been shown to be persuasive across a variety of contexts. But it remains unclear whether this persuasive power advantages truth over falsehood, or if LLMs can promote...
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Tom Costello @tomcostello.bsky.social · 05/03/2026
I saw we were fighting about what AI will do to (social) science. I have some thoughts (originally written for a book on scientific inquiry) and decided to turn them into my first substack article. Co-written with Nat Rabb! tomstello.substack.com/p/standing-o...
tomstello.substack.com
Standing on the Shoulders of Termites
Or, how we learned to stop worrying and love AI (scientists)
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Christopher Barrie @cbarrie.bsky.social · 25/02/2026
🧵on my new paper "Synthetic personas distort the structure of human belief systems" w Roberto Cerina I'm v excited about... 🚨 Do synthetic samples look like human samples? We compare 28 LLMs to the 2024 General Social Survey (GSS) to find out + develop host of diagnostics...
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Tom Costello @tomcostello.bsky.social · 23/02/2026
I'm hiring a postdoc at @cmu.edu (w/ far.ai & @dgrand.bsky.social + @gordpennycook.bsky.social)! How do LLMs shape human beliefs — and what do we do about it? AI safety meets behavioral science. Open to technical and social science backgrounds.
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Tom Costello @tomcostello.bsky.social · 23/02/2026
I'm hiring a postdoc at @cmu.edu (w/ far.ai & @dgrand.bsky.social + @gordpennycook.bsky.social)! How do LLMs shape human beliefs — and what do we do about it? AI safety meets behavioral science. Open to technical and social science backgrounds.
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Mackenzie Lockhart @maclockhart.bsky.social · 18/02/2026
🚨 New paper out at @ajpseditor.bsky.social 🚨 Do the public hold meaningful attitudes? Using the case of abortion policy preferences, we provide strong evidence that policy prefrences can be coherent, stable over time, and causally explain vote choice. doi.org/10.1111/ajps...
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Gordon Pennycook @gordpennycook.bsky.social · 18/02/2026
New paper in Current Directions in Psych Science: journals.sagepub.com/doi/10.1177/... After countless arguments about what tasks ppl should/should not offload to AI, we instead argue that genAI can be used *augment* research protocols in novel ways. I.e. use AI to make better psych experiments!
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Tom Costello @tomcostello.bsky.social · 13/02/2026
Honored (and genuinely, wildly grateful and -- even more than I am grateful -- surprised) to share that our paper "Durably reducing conspiracy beliefs through dialogues with AI" received the @aaas.org Newcomb-Cleveland Prize (for the "most outstanding" paper in @science.org last year).
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Robb Willer @robbwiller.bsky.social · 09/02/2026
🚨New WP: Can an AI voter guide (grounded in information from a nonpartisan, fact-checked source) help voters’ decision making? 🚨 We built and evaluated an LLM-based chatbot that provided voting info in CA & TX (N=2,474) right before the 2024 election. 🧵👇
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Hank Green @hankgreen.bsky.social · 28/01/2026
If the medium is the message, then the message of algorithmic content platforms is not expression or connection or freedom. It is salience above all else. This is what is happening to us on these platforms. They cannot behave any other way.
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Penguin Press @penguinpress.bsky.social · 27/01/2026
The #1 New York Times bestseller The Sirens’ Call is now in paperback! Chris Hayes masterfully explores how our focus has been commodified & manipulated, urging us to reclaim control over our lives & future. The Sirens’ Call is the big-picture vision we urgently need to offer clarity & guidance.
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Drew Stommes @drewstommes.bsky.social · 27/01/2026
After years in academia, I’m exploring data science and research roles in industry. I'm a quant. social scientist (PhD Yale ’24, NYU) focused on causal inference, experiments, and large-scale data. Feel free to get in touch or share; all leads appreciated. dwstommes@gmail.com
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FAR.AI @far.ai · 20/01/2026
Our latest collaboration with CMU, Cornell, and others: AI is just as effective at spreading conspiracy beliefs as it is at debunking them. We found a fix that works, showing that we need to make deliberate design choices. Full thread below.
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Tom Costello @tomcostello.bsky.social · 20/01/2026
If you tell an AI to convince someone of a true vs. false claim, does truth win? In our *new* working paper, we find... ‘LLMs can effectively convince people to believe conspiracies’ But telling the AI not to lie might help. Details in thread
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Tom Costello @tomcostello.bsky.social · 20/01/2026
If you tell an AI to convince someone of a true vs. false claim, does truth win? In our *new* working paper, we find... ‘LLMs can effectively convince people to believe conspiracies’ But telling the AI not to lie might help. Details in thread
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Dan Williams @danwphilosophy.bsky.social · 22/12/2025
A very interesting data-rich analysis of persuasion on digital media by @benmtappin.bsky.social. Recommend! open.substack.com/pub/benmtapp...
open.substack.com
For Digital Mass Persuasion, Exposure Matters More Than Persuasiveness
If you are interested in understanding the mass persuasive impact of digital media content you should generally pay more attention to content exposure than to its persuasiveness.
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conputer dipshit @davidcrespo.bsky.social · 22/12/2025
in 2025 the combination of the latest models and agentic harnesses like Claude Code (currently considered tools for coders) felt like a step change for software engineers and, it seems, for mathematicians as well. in 2026 this will hit every other white collar job xcancel.com/Aaroth/statu...

Aaron Roth
@Aaroth
19h
Starting in the fall (Gemini 2.5 pro launched experimentally at the end of March) LLMs that were useful for math launched. I didn't have much luck using them within their web interface, but I found them to be extremely useful within coding agent harnesses like Windsurf.
Aaron Roth
@Aaroth
19h
This setup substantially accelerated writing math. I could "verbally" sketch an argument as if to a colleague, and the tools could turn that into a formally written lemma/theorem with proof. The proof was correct maybe 75% of the time, but could quickly iterate to correctness.
Aaron Roth
@Aaroth
19h
This summer I spent lots of time using these tools, and we wrote a couple of papers with them. The tools had a couple of memorable flashes of insight that simplified things, but for the most part it felt like accelerating writing the same paper we would have written without them.
Aaron Roth
@Aaroth
19h
In the late summer and spring, GPT 5 (and then 5.1 and 5.2) launched. The GPT 5/5.1/5.2 pro model seemed again like another step change. I again spent a lot of time with it. It could provide real complements to my expertise and work through long and complicated lines of reasoning
Aaron Roth
@Aaroth
19h
We wrote a paper that I think is substantially different/better than the one we would have written without it (coming soon)! This is still far from autonomous science --- working with these tools is like collaborating with a broadly educated, smart but error prone colleague.
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conputer dipshit @davidcrespo.bsky.social · 14/12/2025
I’m less polite: the capabilities q is usually an active denial. in skilled hands, SOTA LLM tools are more capable today than most people think. assume they can do X and you can get through to the real question of what people will do with that and what that reveals about the pressures they’re under
I don’t have a program for reform, but I also don’t think reform is possible unless we change the way we look at the problem. What I’ve tried to do here is make a different question askable—not whether LLMs can “do science” but how they get enrolled within a scientific system whose goals have already been displaced. The capabilities debate has been a way of not seeing the institutional context in which these tools arrive.
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Hank Green @hankgreen.bsky.social · 10/12/2025
I'm gonna resonant computing so hard that my adaptive pluriverse becomes as prosocial as a god damned golden retriever. resonantcomputing.org
resonantcomputing.org
The Resonant Computing Manifesto
Technology should bring out the best in humanity, not the worst—a manifesto for resonant computing built on five principles that reject hyper-scale extraction for human flourishing.
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jon ben-menachem @jbenmenachem.com · 08/12/2025
Our new study provides rare causal evidence about NYC’s speed camera program. We find large reductions in collisions (30%) and injuries (16%) near intersections with cameras. www.pnas.org/doi/abs/10.1... @astagoff.bsky.social ky.social @brendenbeck.bsky.social nbeck.bsky.social 🧪
pnas.org
Can speed cameras make streets safer? Quasi-experimental evidence from New York City | PNAS
Each year, approximately 40,000 people die in vehicle collisions in the United States, generating $340 billion in economic costs. To make roads saf...
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Tom Costello @tomcostello.bsky.social · 06/12/2025
IMO, if we want to live in a democracy, we ought to embrace persuasion. When we treat all AI info as bad we are implicitly arguing that voters are incapable of processing arguments. This is an illiberal stance. democracy relies on the "unforced force of the better argument." (Habermas)
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Tom Costello @tomcostello.bsky.social · 06/12/2025
Any headline that ends in a question mark can be answered by the word “no” (Betteridge's law). Should we worry about gen AI persuasion shaping elections? I think “no” holds here. See knightcolumbia.org/content/dont... for a good summary of why we shouldn’t be too concerned
knightcolumbia.org
Don’t Panic (Yet): Assessing the Evidence and Discourse Around Generative AI and Elections
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Tom Costello @tomcostello.bsky.social · 05/12/2025
I encourage folks to read the actual paper — the models were prompted to change opinions…not to be accurate. Humans also use inaccurate information. But the AIs were still reasonably accurate (Avg 77/100), with no evidence inaccurate claims are more persuasive.
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Will Oremus @willoremus.com · 04/12/2025
New: AI chatbots can change voters' minds, according to a pair of in-depth studies published just now in Science and Nature. How they do it is interesting — and concerning. Gift link: wapo.st/49RSstP
wapo.st
Voters’ minds are hard to change. AI chatbots are surprisingly good at it.
New research suggests AI chatbots can shift people’s political views more effectively than campaign ads on TV.
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Tom Costello @tomcostello.bsky.social · 04/12/2025
Very excited this paper is live! Congratulations to first author Hause Lin for being such a badass researcher and all around cool guy
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Jordan Axt @jordanaxt.bsky.social · 02/12/2025
New paper in press at JPSP! An adversarial collaboration focusing on a large-scale test of how strongly implicit racial attitudes predict discriminatory behavior. Pre-print here: osf.io/preprints/ps...
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Michael Inzlicht @minzlicht.bsky.social · 28/11/2025
Excited to share work led by Conrado Eiroa-Solans, a PhD student at UC Berkeley who I first met when he was applying to grad school. His new paper is out in Computers in Human Behavior Reports. /1
sciencedirect.com
From Extrinsic to Intrinsic Motivation: Testing an AI-powered Motivational Interviewing System to Foster Prosocial Motivation
Scalable interventions promoting sustained behavioral change are crucial for addressing societal issues, yet traditional approaches often require inte…
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Tom Costello @tomcostello.bsky.social · 21/11/2025
Cool review of conversational AI interventions for reducing misbeliefs ! www.sciencedirect.com/science/arti... “LLMs have clear communication advantages: they are highly accessible, interactive, conversationally engaging, multi-lingual, and responsive to individuals’ unique information needs.”
sciencedirect.com
Using conversational AI to reduce science skepticism
Mistrust of the scientific consensus around issues such as climate change and vaccination is mainstream, compromising our ability to respond to existe…
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Jennifer Tackett @jnfrltackett.bsky.social · 12/11/2025
Y'all. N>3,800. !!!!!!! Goodness gracious.
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Tom Costello @tomcostello.bsky.social · 07/10/2025
I’m going to be in Montreal for a few days starting tomorrow for COLM — anyone also at the conference / interested in meeting up, let me know!
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Florian Foos @florianfoos.bsky.social · 28/07/2025
This is a valid point, I think. The question is always what type of alternative information gathering processes AI chatbots replace. In the case of medical "self diagnosis", there is some reason to believe that common alternative mechanisms aren't superior.
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Tom Costello @tomcostello.bsky.social · 24/07/2025
Targeted ads have gone too far
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Scott McGrath @smcgrath.phd · 16/07/2025
Thomas Costello argues that as patients move from WebMD to AI, we might be slightly optimism. Unlike former tools, LLMs can synthesize vast, shared knowledge, potentially helping users converge on more accurate beliefs. The major caveat is: as long as the LLMs are not trained on bad data.
nature.com
Large language models as disrupters of misinformation - Nature Medicine
As patients move from WebMD to ChatGPT, Thomas Costello makes the case for cautious optimism.
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Tom Costello @tomcostello.bsky.social · 17/07/2025
Is there a strong case for AI helping, rather than harming, the accuracy of people's beliefs about contentious topics? In this @nature.com Nature Medicine piece (focusing on vaccination), I argue the answer is YES. And it boils down to how LLMs differ from other sources of information.
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Robert Califf @robcaliff.bsky.social · 16/07/2025
This is an interesting take on LLMs and the RCT in vaccine hesitancy is fascinating. www.nature.com/articles/s41...
nature.com
Large language models as disrupters of misinformation - Nature Medicine
As patients move from WebMD to ChatGPT, Thomas Costello makes the case for cautious optimism.
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Tom Costello @tomcostello.bsky.social · 09/07/2025
Conspiracies emerge in the wake of high-profile events, but you can’t debunk them with evidence because little yet exists. Does this mean LLMs can’t debunk conspiracies during ongoing events? No! We show they can in a new working paper. PDF: osf.io/preprints/ps...
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David Rand @dgrand.bsky.social · 09/07/2025
I'm very excited about this new WP showing that LLMs effectively countered conspiracies in the immediate aftermath of the 1st Trump assassination attempt, and that treatment also reduced conspiratorial thinking about the subsequent 2nd assassination attempt
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Tom Costello @tomcostello.bsky.social · 09/07/2025
Conspiracies emerge in the wake of high-profile events, but you can’t debunk them with evidence because little yet exists. Does this mean LLMs can’t debunk conspiracies during ongoing events? No! We show they can in a new working paper. PDF: osf.io/preprints/ps...
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Nicole Rust @nicolecrust.bsky.social · 02/07/2025
Here's a bit of spice. Brain research clearly needs to tackle more complexity (than, say, Step 1: simple linear causal chains). But that leaves an ~infinite set of alternatives. Here, @pessoabrain.bsky.social advocates not for just a step 2, but a 3. /1 arxiv.org/abs/2411.03621
arxiv.org
Beyond networks, towards adaptive systems
Despite their widespread utility across domains, basic network models face fundamental limitations when applied to complex biological systems, particularly in neuroscience. This paper critically exami...
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Vlad Ayzenberg @vayzenb.bsky.social · 02/07/2025
My paper with @stellalourenco.bsky.social ‬is now out in Science Advances! We found that children have robust object recognition abilities that surpass many ANNs. Models only outperformed kids when their training far exceeded what a child could experience in their lifetime doi.org/10.1126/scia...
doi.org
Fast and robust visual object recognition in young children
The visual recognition abilities of preschool children rival those of state-of-the-art artificial intelligence models.
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Tom Costello @tomcostello.bsky.social · 25/06/2025
This is a stellar paper -- highly recommend if you want an incisive birds-eye view of AI + political science www.annualreviews.org/content/jour...
annualreviews.org
AI as Governance | Annual Reviews
Political scientists have had remarkably little to say about artificial intelligence (AI), perhaps because they are dissuaded by its technical complexity and by current debates about whether AI might ...
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Tom Costello @tomcostello.bsky.social · 30/05/2025
It’s my birthday, so today seems like as good a time as any to share that, this summer, I’ll be joining Carnegie Mellon University as an assistant professor in the Department of Social and Decision Sciences (w/ courtesy in HCI institute).
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Gordon Pennycook @gordpennycook.bsky.social · 29/05/2025
New paper in PSPB! journals.sagepub.com/doi/10.1177/... Well, actually, not "new". We first put this paper online way back Dec 2022... in any case, we think it's really cool! We find that conspiracy believers tend to be overconfident & really don't seem to realize that most disagree with them
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Tom Costello @tomcostello.bsky.social · 27/05/2025
In trying to get purple Connections first, I ended up with a sequence of guesses that was unique across all other players. I think impossible to replicate this while earnestly trying to get puzzle right?
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