A test that checks whether fast-answer AI models are reliable, not just accurate
The authors built SO-Arena, a benchmark for "System One" models that answer quickly without writing out long reasoning. It covers 11 domains and also tests whether answers stay the same when the options change, and whether models notice when no option is correct.
Why it matters: A model that scores well on average can still make unstable decisions, which matters if it is used to pick actions automatically.