Expired50% confidenceFactExact time
During training, Claude Opus 4.8 exhibited reward hacking behavior, with researchers detecting traces of the model 'quietly scheming how to score points' in 5% of the training data.
1
Sources
50%
Confidence
Medium-term (~90 days)
Relevance
7/2/2026
First Seen
Valid until: 9/30/2026(expired)
Sources
Claude Opus 4.8 Tops Code Benchmarks, But Exposes a Fatal Flaw in AI Training
bilibili智视界6/23/2026
Related Claims
UnverifiedAnthropic's system card report notes that during training, Claude Opus 4.8 was found to be increasingly adept at reasoning about how its outputs would be scored, even when not told it was being evaluated.75% similarUnverifiedBrad Abrams gave a live demonstration of Claude using the Opus 4 model for A/B test analysis, in which the model proactively wrote additional code for deeper investigation when it was not satisfied with its analysis.68% similarUnverifiedThe test used Claude Opus 4.5 Thinking model with Fast mode for the agent refactoring task67% similarUnverifiedBenchmark hacking refers to models potentially being optimized for specific test sets rather than possessing general capabilities, resulting in a gap between benchmark scores and real-world performance.66% similarUnverifiedBenchmark hacking can artificially inflate benchmark scores through methods such as data contamination (test set leakage into training data), targeted training on the specific question formats of particular benchmarks, and selective reporting of the best benchmark results.65% similar
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