How Polarizing Is Your Feed? Now We Can Tell
Build Up’s new polarization footprint, like the carbon footprint, lets us measure the divisive consequences of social media feeds.
The attention economy has always had hidden costs. For the first time, we can measure one of them: polarization.
The polarization footprint is a new metric that scores how much identity-based division appears in a user’s social media feed. Piloted in Kenya by the digital peacebuilding organisation Build Up, it turns a long-standing suspicion — that our feeds are quietly deepening divides — into something we can measure.
The new metric takes inspiration from the carbon footprint, which exposed the hidden costs of industrial growth on the environment. “Polarization should not only be considered a digital harm that drives conflict, but also a negative externality of the attention economy,” writes Build Up in this series of three blogs outlining the methodology and the Kenyan pilot.
Connecting affective polarization to violence
Not all conflict is bad. Disagreement — over taxes, education, or policy — is essential to a healthy democracy. But affective polarization isn’t about differing ideas. It’s about identity.
It emerges when people begin to dislike, distrust, or even dehumanize others because of who they are — their ethnicity, region, religion, political affiliation, or social group. This kind of polarization hardens identity lines and makes compromise feel like betrayal. Disagreement becomes a threat.
A core maxim of peace mediation is to “separate the person from the problem” — to debate content without turning people into enemies. Affective polarization makes that shift nearly impossible. It entrenches mental categories and drives a spiral of hostility that, if widespread, becomes a risk for real-world violence.
“Affective polarization… identifies direct attacks on human dignity… and can ultimately offer a signal for risk of violent conflict and ensuing dramatic consequences for physical and mental wellbeing.” — Build Up
It also explains why fact-checking and counterspeech often fall flat. When people are emotionally invested in a group identity, they’re not just processing information — they’re defending a sense of belonging.
Three signals
The polarization footprint captures affective polarization through three distinct signals:
Attitude polarization: the presence of hateful, dehumanizing, or “othering” language in posts.
Norm polarization: the absence of challenges to such language in comment threads (i.e., when no one pushes back, it becomes normalized).
Interaction polarization: the degree to which users are siloed into different “content universes” — echo chambers with minimal overlap.
Together, these generate a composite score that reflects how much identity-based division a platform’s feed architecture is producing.
The Kenyan experience
Here’s how Build Up piloted this methodology in Kenya in 2025. A representative sample of users voluntarily shared their feeds across platforms — including X, Facebook, YouTube, and TikTok — with researchers and local peacebuilding experts.
Here are the top line findings:
An average Kenyan user on X is likely to spend up to 21 minutes per day engaging with posts that attack identity groups.
Few users challenge these attitudes when they appear — especially on X and YouTube — allowing toxic norms to solidify.
Users on X and YouTube were found to inhabit entirely separate content bubbles, consuming narratives with little to no crossover — a clear marker of interaction polarization.
Facebook, despite middling levels of attitude and norm polarization, showed much lower fragmentation, suggesting that more overlapping content ecosystems can help reduce division. Importantly, on video-dominant platforms like YouTube and TikTok, the analysis was limited to text-based content: captions, comments, and descriptions — not the videos themselves.
Echoes from similar research
These findings echo a 2025 Science study by Piccardi et al., titled “Reranking partisan animosity in algorithmic social media feeds alters affective polarization” The researchers reranked the feeds of American social media users on X to either increase or decrease exposure to two types of content:
Polarizing content, defined as content that increases animosity toward political outgroups
Content that undermines democratic norms, such as encouraging political violence or delegitimizing elections
As a result:
Users shown more polarizing content reported colder feelings toward political opponents.
Those shown less became warmer toward opposing groups.
These shifts were equivalent to reversing or accelerating three years of U.S. polarization — after just one week.
The researchers point out that the attitude shifted — not because of what they chose to engage with, but because of how the system ranked what they saw.
Polarization as part of DSA risk assessment
While not yet deployed in Europe, “Very Large Online Platforms - how big is your Polarization Footprint?” by Build Up’s Guy Banim suggests it could offer a valuable tool for the DSA risk assessment cycle, allowing for disaggregated measurement of feed-level risks to civic discourse and social cohesion.
Under the EU Digital Services Act, Very Large Online Platforms (VLOPs) are required to assess how their design and algorithmic systems affect civic discourse and public safety. The polarization footprint offers them — and regulators — a measurable signal of how identity-driven division is being shaped by platform architecture.
From metrics to mitigation
Platforms are designed to keep us engaged. And content that divides — especially along identity lines — drives engagement. The footprint allows us to track this harm in the system itself.
“The polarization footprint reveals deepening societal divides driven by affective polarization… Addressing it requires a shift from individual responsibility to collective action,” according to Rachel Olpengs, coordinator of Kenya’s freedom of expression coalition FECoMo.
Here are some ways we could put this metric to use:
Label it: Like a food or eco-score, show users which platforms are most polarizing.
Tax it — or incentivize change: Price polarization into the platform’s business model, or offer rebates to advertisers who choose less polarizing platforms.
Regulate it: Use empirical metrics to inform laws like the EU’s Digital Services Act, where systemic risk is already part of the framework.
The polarization footprint doesn’t offer a silver bullet. But it gives us something we’ve long lacked: a rigorous way to quantify how much our feeds are shaping division. It opens the door to real accountability — not just for platforms, but for regulators, designers, and society at large.
Lena Slachmuijlder is Senior Advisor for digital peacebuilding at Search for Common Ground, a practitioner fellow at the USC Neely Center, and co-chair of the Council on Tech and Social Cohesion.