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Auto-shown AI answers cut 'I don't know' from 35 percent to 1 percent in a movie-trivia study
Researchers found an auto-displayed AI answer cut 'I don't know' responses from 35 percent to 1 percent, though the model was mostly wrong. A 10-cent penalty for wrong answers still left abstention at 7 percent, so review tools need more than an abstain button.
The Engineer · Build desk

What happened
- Five experiments with 3,132 participants asked about fine visual details from films, questions the Step 3.5 Flash model almost always got wrong.
- When participants could choose to consult the AI, the share of questions they declined to answer fell from 36 and 44 percent to 6 and 3 percent in Studies 1a and 1b.
- In Study 2, confidence with AI access rose to 75.9 out of 100 from 29.6 without it, while the share of correct answers fell from 27.6 to 10.0 percent.
- A pre-registered test across three studies found no statistically significant interaction between AI access and a 10-cent reward-and-penalty scheme.
- When the AI answer appeared automatically in Study 4, abstention fell from 35 to 1 percent without incentives and from about 39 to 7 percent with them.
Compiled by The EngineerSomething wrong?How this is made
Why it matters
- constraint An abstain option scored above a wrong answer still went largely unused beside AI advice, so an abstain button by itself is a weak safeguard in a tool that shows reviewers AI suggestions.
- decision Putting the suggestion behind a click bought little over showing it automatically, so the design choice left to test is when the suggestion appears relative to the reviewer's own answer.
- exposure A QA process that audits the reviews people marked low-confidence will pick the wrong items once AI suggestions are on screen.
Every condition offered an "I don't know" option. From Study 2 on it was priced: 10 cents for a correct answer, minus 10 cents for a wrong one, nothing for abstaining [9]. Under that rule an answer pays only when the chance of being right is above 50 percent [12]. Paying people helped a little. In Study 3 it cut AI requests from 5.27 to 4.53 out of six, and abstention rose slightly but stayed well below the no-AI group [11]. The accuracy figures in the report come from the unpaid arms, where people with AI access got 9.2 percent of questions right against 27.5 percent without it [7]. The AI group was right about a third as often [8].
Study 4 matches any tool that pre-fills a suggestion for a reviewer. The AI answer appeared without being requested, and the effect barely changed from the studies where participants had to ask for it [13]. The researchers say this setup mirrors AI summaries in search results and unsolicited suggestions from writing assistants [14].
The authors place the cause in the model's behaviour. They write that a language model always has to produce an answer and never pauses, and that people who hand it their judgment may adopt its lack of restraint [15]. The reported conditions do not include one where the model declined to answer or flagged low confidence. So the case for showing uncertainty inside the suggestion follows from the authors' explanation, and this study does not measure it. For a queue where a wrong approval costs more than a skipped item, I would build two things. One is a model allowed to return no suggestion. The other is a form that records the reviewer's own answer, abstention included, before the suggestion renders. The study tested neither.
The result also cuts against the advice-taking literature. People normally underweight outside advice and move only about a third of the way toward an advisor's position, and participants here did the opposite, the authors say [16]. They conclude that AI access turned some answers that would have been correct into errors [17]. Because the advice was mostly wrong, the pattern cannot be put down to sensible delegation to a reliable tool [20].
The figures describe a chosen workload. The authors picked film details because they rarely appear in online text and so invite hallucination [3], and Step 3.5 Flash was almost always wrong on them [1]. GPT-5.5, Claude 4.6 Sonnet and Gemini 3.5 Flash got most of the other questions right [4]. For the numbers to carry over to a review queue, the reviewer would need to know the item about as poorly as a viewer recalls a costume colour, and have about as little at stake. A reviewer whose name goes on the approval is risking more than a dime. The researchers acknowledge the incentives were modest and say the effect of larger or reputation-based stakes is unknown [19]. The Decoder notes that whether the deference holds as strongly outside movie trivia is still open [18].
What to watch
- A replication with larger or reputation-based stakes, the incentive design the researchers say remains untested.
- A condition where the model itself can decline or flag low confidence, to see whether model-side abstention restores human abstention.
- Results on question sets outside film trivia, where GPT-5.5, Claude 4.6 Sonnet and Gemini 3.5 Flash are mostly right.