New paper fixes contrastive RL blind spot by re-weighting InfoNCE with 1-bit failure signal

kastnerkyle · x · 2026-09-06

• A newly recommended contrastive RL (CRL) paper identifies a long-standing blind spot: InfoNCE only draws positive pairs from surviving steps, ignoring the missing probability mass from failure terminations
• This makes the critic delusionally optimistic near death traps, tricking the policy into reckless moves just before dying
• Instead of safety reward hacks, the authors use a basic 1-bit failure signal to re-weight InfoNCE and fold survival mass back into policy updates
• Across 12 benchmark tasks, results are similar on simple Point/Car setups, but the gap on harder Ant and Humanoid pitfall runs with hazards is night and day
• The sharer argues this fixes a problem that has troubled many researchers

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