Assess MSM’s impact on chain-of-thought monitorability

Investigate how Model Spec Midtraining affects chain-of-thought monitorability in language models, specifically determining whether MSM degrades, preserves, or enhances the reliability with which evaluators can monitor and audit chain-of-thought reasoning after post-training.

Background

The authors show that stacking Model Spec Midtraining with alignment fine-tuning can reduce reliance on chain-of-thought supervision while achieving strong safety performance, which interacts with concerns that direct chain-of-thought training can compromise monitorability.

They explicitly flag uncertainty about whether MSM changes chain-of-thought monitorability, motivating empirical investigation into the safety implications of MSM for reasoning transparency.

References

Stacking MSM with reasoning post-training can achieve comparable performance with dramatically fewer CoT training samples, although the effect of MSM on CoT monitorability is an open question.

— Model Spec Midtraining: Improving How Alignment Training Generalizes  (2605.02087 - Li et al., 3 May 2026) in Discussion, subsection "MSM is not the only way to teach the right reasons."