Circuit

A proposed set of model components and interactions that implements or contributes to a defined behavior.

Researchers identify candidate attention heads, neurons, features, or paths, then test whether removing, replacing, or activating them changes the target behavior. A circuit can be local to a narrow task and need not be the only route that produces the result. Large models may use redundant or distributed mechanisms that resist a compact diagram.

Builder example

Circuit analysis can support a causal explanation when interventions predict behavior on held-out inputs. It does not yet offer an exact pathway for every production failure, and a circuit found on one model or prompt family may not transfer.

Common confusion: Circuit is an analysis abstraction, not a literal physical subassembly. Its boundaries depend on the behavior and method chosen by the researcher.