Przemek Grabowicz 🇵🇱🇪🇸🇩🇪🇺🇸🇮🇪

"They were girls who went to school to learn, with hopes and dreams for their future," Nobel Peace Prize winner Malala Yousafzai said. "Today, their lives were brutally cut short.”

Read more: https://wapo.st/4r7izC7

👩🏼‍💻 None of this would be possible without the brilliant minds and tireless efforts of the members of the SIMS Lab. Your passion, commitment, and collaborative spirit are the driving force behind our success. Thank you for making 2025 such a fantastic year! 6/

🌐 We also contributed to digital policy discussions through the @ucddigitalpolicy.bsky.social and the Social Data Science Alliance, bringing research-grounded insights into ongoing debates about platform governance. 5/

🏛️ Beyond academia, we worked with public institutions including @zdfde.bsky.social and NASK, studying political biases on X before elections in Germany and Poland. Our reports were read by tens of thousands and featured on national TV — underscoring the real-world relevance of our research. 4/

📚 We published 6 research papers at @icwsm.bsky.social, @neuripsconf.bsky.social, @aamasconf.bsky.social, and @facct.bsky.social on explainability and fairness. We were especially honored to receive a Best Paper Honorable Mention at ICWSM for our study “Election Polls on Social Media”. 3/

🌍 Being transatlantic is not just a geographic detail. It shapes how we think, collaborate, and engage — bridging perspectives across Europe and the U.S. while studying the transparency and fairness of AI systems and social media algorithms. 2/

The past year was remarkable for the SIMS Lab — our transatlantic research lab, spanning @ucddublin.bsky.social and @umassamherst.bsky.social. I'm grateful, proud, and energized for what’s next!
🖥️ Our new website: przemyslslaw.github.io/sims-lab
📸 Photo from my recent trip to Amherst
🧵 1/6

Open Social Web Series 🌐

Building on the AT Protocol means we don't have to build alone 🙌🏽

Mentions: @jonathanstray.bsky.social @graze.social @stream.place @gandersocial.bsky.social @transrights.northsky.social @skylight.social

#OpenSocialWeb #SkylightSocial #BuildWithTori

To achieve algorithmic fairness we need to bridge AI technology with society and legal systems Researchers are calling for a more ambitious study of algorithmic fairness that bridges AI technology with social and legal components.

Researchers such @randomwalker.bsky.social are calling for a more ambitious study of algorithmic fairness that bridges AI technology with social and legal components. Our research provides insights how to achieve that. More in our new Uncommon Good post!
uncommongood.substack.com/p/to-achieve...

We’re looking forward to continuing the conversation and contributing to an implementation of the DSA that’s beneficial to the citizens of the EU and all involved stakeholders. 2/2

Our upcoming Opinion article in the Communications of the ACM (CACM) discusses the hotly debated Digital Services Act (DSA) — online platform transparency and accountability regulation of the EU. 1/2
uncommongood.substack.com/publish/post...

Happy to announce that our Opinion article about the hotly debated EU’s Digital Services Act (DSA) has been accepted for publication in Communications of the ACM!

Preprint here: arxiv.org/abs/2512.14223

AI-generated ‘participants’ can lead social science experiments astray, study finds Data produced by “silicon samples” depends on researchers’ exact choice of models, prompts, and settings

You mean I can't just make up people instead of studying people? www.science.org/content/arti...

If you're interested in pursuing a PhD in #AI and/or #DataScience with me and/or my colleagues as your supervisors, apply for this fully-funded PhD scholarship at UCD School of Computer Science!

I'm honored to join UCD Center for Digital Policy in the times when digital transparency and policy matter more than ever. 🇪🇺🇺🇸
(Just to clarify, I'm an Assistant Professor, hopefully soon an Associate Professor.)

Europe Fined X, But It's Still Avoiding the Real Threat to Democracy | TechPolicy.Press The European Commission's enforcement action is not sufficient to address the systemic risks posed by X, says MEP Alexandra Geese.

The EU’s €120M fine on Musk’s X is a first step, yet the platform remains a vector for a broader US agenda steering Europe to the right, says Alexandra Geese, an MEP from Germany. Oversight must match the scale of the threat to Europe’s sovereignty, she argues.

🚨 New in Nature+Science!🚨
AI chatbots can shift voter attitudes on candidates & policies, often by 10+pp
🔹Exps in US Canada Poland & UK
🔹More “facts”→more persuasion (not psych tricks)
🔹Increasing persuasiveness reduces "fact" accuracy
🔹Right-leaning bots=more inaccurate

Today, social media platforms hold the sole power to study the effects of feed-ranking algorithms. We developed a platform-independent method that reranks participants’ feeds in real time and used this method to conduct a preregistered 10-day field experiment with 1256 participants on X during the 2024 US presidential campaign. Our experiment used a large language model to rerank posts that expressed antidemocratic attitudes and partisan animosity (AAPA). Decreasing or increasing AAPA exposure shifted out-party partisan animosity by more than 2 points on a 100-point feeling thermometer, with no detectable differences across party lines, providing causal evidence that exposure to AAPA content alters affective polarization. This work establishes a method to study feed algorithms without requiring platform cooperation, enabling independent evaluation of ranking interventions in naturalistic settings.

New paper in Science:

In a platform-independent field experiment, we show that reranking content expressing antidemocratic attitudes and partisan animosity in social media feeds alters affective polarization.

🧵

Our first NeurIPS paper on fair representation learning with controllable guarantees. Fantastic research, and a result of extremely dedicated work by @jamesluoyh.bsky.social and our team! Well done! 🎊

The worst happened. We were DOGE’d. Our NSF funding is gone.

So now there’s nothing stopping me from sharing Expert Voices Together, a crisis response system for US-based researchers and journalists facing harassment.

It's a true passion project. 🧵 1/

expertvoicestogether.org

Polish flag overlaid with X logo with charts

X's Algorithm Amplifies Political Extremes
Prof. @przemyslslaw.bsky.social studied #X during Poland's 2025 election:
📊 Far-right & far-left posts stay in feeds longer
📉 Ruling party content down-ranked 4x
📈 80% feed content now from outside your network
zenodo.org/records/1751...
#AlgorithmicBias

In recent months, I've seen videos showing Israeli settlers harassing Palestinian women harvesting olives, killing baby goats of Palestinian families, and destroying olive trees on Palestinian lands. Why is this happening? Aren't there policemen and courts prosecuting these crimes?

A small correction: the percentage from outside the network went up from 50% to 80%.

We believe that the only way to achieve neutrality ⚖️ and free speech 💬 in social media is through transparency. Right-wing and left-wing policymakers need to talk with each other and online platform representatives to figure out how independent researchers can safely study social media. 🧵7/7

This research subsumes our previous study of the 2025 German federal election (attached figure and paper), before which Elon Musk supported and campaigned for the far-right AfD. We conclude that social media platforms can develop in different ways. 🧵6/7
zenodo.org/records/1489...

Elon Musk on X: "A major update to the recommendation algorithm is rolling out over the next few days. This will help surface smaller accounts and posts outside of your friend-follows network. As always, this will be made open source and undergo continuous improvement." / X A major update to the recommendation algorithm is rolling out over the next few days. This will help surface smaller accounts and posts outside of your friend-follows network. As always, this will be made open source and undergo continuous improvement.

We find that the fraction of posts from outside the network went from 20% to 50% following the 2023 change of the algorithm announced by X owner Elon Musk (attached tweet). It's possible that the algorithm also started to amplify political extremes around that time. 🧵5/7
x.com/elonmusk/sta...

A prior study by @inference.vc of the 2016 Twitter's feed algorithm did not find evidence of amplification of political extremes in seven countries, including Germany (attached figure), so the feed algorithm of X must have changed considerably since then. In fact, it did, as we show next. 🧵4/7

We test whether the feed algorithm favors political extremes, by regressing the number of feed appearances against user engagements received by each post and political party affiliation of its author. We find that each post from political extremes appeared about 20 minutes more in the feed! 🧵3/7

The study (attached) was conducted during the culminating month of Polish presidential election. We tracked news feeds of four sock-puppet accounts and analyzed public posts of 485 Polish politicians and related users. 🧵2/7
doi.org/10.5281/zeno...

Our latest study of "Algorithmic Biases on X before the 2025 Polish Presidential Election" reveals that the default algorithmic feed of X showed mostly posts from right-wing parties and amplified political extremes, most likely due to the 2023 updates of X following its takeover (read on). 🧵1/7