We show that Sparse Autoencoders (SAEs), despite their promise for interpretability, are highly unstable. We introduced two new benchmarks to assess SAW dictionary quality, and propose Archetypal SAEs (A-SAEs), which constrain dictionary atoms to the data’s convex hull, greatly improving stability. Our relaxed version, RA-SAE, matches top reconstruction performance and consistently learns more structured, meaningful representations.
This review discusses the current frontier of mechanistic interpretability, which aims to understand the computational mechanisms underlying neural networks. While the field has made progress, many open problems remain, including the need for improved methods, better applications to specific goals, and engagement with socio-technical challenges.