Test-Time Collective Action: Proxy-Based Perturbations for Correcting Algorithmic Harms
Test-Time Collective Action (TTCA) allows a group of users to correct algorithmic bias affecting under-served subgroups without needing platform retraining. Users pool their queries to create a proxy model, optimize per-class perturbations against this proxy, and apply these corrections at test time. This method proves that coordinated user action is cheaper and more effective than individual attacks for subgroup fairness.