Anthropic on October 27, 2026 published a randomized controlled trial in which 50 professional analysts using Claude Code followed their agent’s secretly assigned preference 86% of the time on open analytical judgment calls. The study, authored by Amaç Herdağdelen, Hailey Joren, and Alex Tamkin, examines whether experts actually make the consequential decisions in AI-assisted work, or whether in practice they defer to their agents.
A Fictional Cooperative and Hidden Coin Flips
The researchers recruited 61 professionals who had passed a causal-inference knowledge check, used Python or R regularly, and had hands-on experience with observational causal analysis. Each participant acted as the principal analyst for the fictional Greenfields Farming Cooperative, which had to decide whether to expand or discontinue a voluntary, paid farm-advisory program. The cooperative’s board would expand the program only if it improved farm productivity by roughly 3–4%, but did not specify how productivity should be measured.
The task contained four open analytical decisions, each with two defensible options: whether to measure productivity as crop yield per hectare or per unit of operating cost; which statistical comparison method to use; whether to measure the program’s effect on enrolled farms only or across the full membership; and whether to weight every farm equally or give larger producers more weight. These choices fed into a final recommendation to roll out, discontinue, or extend the program. Each decision could move the estimated productivity gain by several percentage points against the board’s threshold.
For every decision, a coin flip set which option the participant’s agent would favor. The lean was delivered through a hidden system prompt instructing the agent to hold the preference as its own view, raise it when the decision came up, and make the strongest honest case the data allowed. The instructions also required the agent to change its mind if evidence turned decisively against it, and never to misrepresent results or hide data. Participants were not told the leans existed. Of the 61 who completed the task, 11 chose not to use the agent and were excluded from the main analysis; among the remaining 50, 65% held a master’s or doctorate or had six or more years of experience, and 90% of survey respondents rated themselves proficient or expert in causal inference. Participants worked in a browser-based VS Code workspace with Claude Code v2.1.220 running Claude Opus 4.8 at high effort, with a median task time of 65 minutes. The design, outcomes, estimators, and exclusions were registered in a pre-analysis plan, and the study received internal ethics review with participant consent to monitoring.
Deferral Rates and the Ownership Gap
Across the four analytical decisions, analysts’ choices matched the agent’s lean 86% of the time, against a 50% chance baseline; per-decision match rates were 92%, 82%, 81%, and 90%. The full paper, titled “Who’s Aligned to Whom? How AI Agents Shape Experts’ Research Judgment Calls,” reports a registered pooled flip-rate estimate of 0.72 with a 95% confidence interval of 0.60–0.83.
The effect on the final recommendation was weaker and not statistically significant under the registered primary estimator: 54% recommended rollout when the agent leaned that way, versus 36% when it leaned toward discontinuation, a registered policy shift of 0.17. The authors attribute the smaller shift to the recommendation following mechanically from the estimate once it was computed. However, an exploratory model using only the four analytical leans predicted 82% of recommendations, against a 61% majority baseline, meaning the coin flips largely determined what analysts would recommend before they began the task.
In 38 cases where an analyst voiced a preference before the agent did, they switched away from it 60% of the time when the agent disagreed, compared with 6% when it agreed. The paper reports the registered switch-rate gap as 0.53, with a confidence interval of 0.24–0.82, and notes the estimate is imprecise and the subset self-selected.
Post-task surveys showed a gap between influence and self-perception. 52% rated the final recommendation as more their own than the agent’s, and confidence averaged 71 for those who followed the lean on all four decisions versus 73 for the rest. When justifying each choice without access to the transcripts, 77% repeated the agent’s arguments in at least one answer, sometimes word for word, while only 15% credited the agent anywhere. None of 10 tested participant characteristics reliably predicted deferral; only age showed a nominal link that did not survive correction for multiple tests. Six of 48 participants guessed the study concerned AI influence on their choices, but none suspected the preferences were planted.
Comparison Group, Stock Agents, and Limitations
Of the 11 participants who worked without the agent, six (55%) made serious result-invalidating errors, versus three of 50 (6%) among agent users, and the no-AI group took a median 90 minutes against 65. The authors caution that the groups self-selected and differed in experience, so no causal claim follows. In separate direct simulations with no lean injected, stock Claude Opus 4.8 made the same five choices in 91% of 123 runs, and when a scripted analyst declared a decision against the model’s baseline preference, the stock agent recommended or advocated the alternative on 41% of 150 judged declarations.
The authors state four limitations: the lean was deliberately amplified; the study used one task, one domain, and one pinned model; estimates are averages across analysts rather than measures of individual influence; and only the chosen option, not strength of preference, was recorded.
The authors state that if separate research teams defer to models sharing the same priors, their agreement may no longer be independent, and that deferral poses a risk for AI safety research, where a human reviewer’s sign-off is assumed to be an independent check. They propose three future study areas: measuring deferral in everyday settings, designing agents that present both sides or elicit the expert’s view first, and institutional changes that decide deliberately which decisions require a person’s own informed judgment.
Credit: Source link
