In an Anthropic randomized trial published October 27, 2026, 50 causal-inference practitioners using Claude Code chose the option their agent was secretly assigned to favor on 86 percent of analytical decisions. Most justified choices in the agent's words without crediting it. The study covers one task and one model.
Anthropic's chart from its randomized trial: on the four analytical decisions, the share choosing option A was 62 to 82 percentage points higher when the agent had been secretly assigned to favor A. The final recommendation moved 17 points; its direct effect was not statistically significant in the primary analysis. One task, field, and model, with the leans deliberately strengthened. Anthropic · Copyright Anthropic PBC; attributed editorial excerpt, no reuse license
