mechanistic analysis of synthetic-data-induced model collapse

investigating how model collapse manifests inside language model internals and whether lost capabilities are gone or merely inaccessible

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overview

Investigating how model collapse manifests inside language model internals — tracing where degradation originates, what drives it, and whether collapsed capabilities are destroyed or merely unreachable.

Timeline: August 2026 – Present
Advisor: Dr. Maria Leonor Pacheco, BLAST Lab
Status: In progress

research progress

  • Investigating how model collapse manifests inside language model internals, showing recursively trained model generations are linearly decodable from activations with near-perfect accuracy.
  • Comparing different training regimes to disentangle pure data drift from compounding parameter drift.
  • Using neuron ablation and activation patching to causally localize where collapse-related information concentrates in the network.
  • Testing whether activation steering can repair collapsed behavior, probing whether lost capabilities are gone or merely inaccessible.