AI advice suppresses people's willingness to say "I don't know", even when the advice is wrong and accuracy is incentivized

2026-07-15

AI Summary

This study demonstrates that the mere presence of AI suggestions significantly suppresses individuals’ willingness to respond “I don’t know” on difficult questions—even when the AI’s advice is entirely inaccurate and participants are incentivized for accuracy—thereby impairing judgment and metacognition. Across five preregistered experiments (N = 3,132), the authors establish for the first time that AI presence alone, under conditions of zero AI accuracy, reduces the propensity to withhold judgment and elevates metacognitive response thresholds. Specifically, exposure to AI suggestions drives omission rates toward zero, decreases objective accuracy to roughly one-third of baseline levels, and nearly doubles subjective confidence. Critically, these detrimental effects persist despite financial incentives for correctness, with judgmental conservatism remaining substantially below baseline.

Abstract

Knowing when to say "I don't know" is fundamental to human judgment, yet AI assistants offer a fluent answer to almost any question. In five experiments (N = 3,132; four preregistered, one direct replication), participants answered difficult questions and could always decline to respond. We engineered the questions so that AI advice was wrong, separating AI use from its accuracy. Merely having access to AI nearly eliminated participants' willingness to suspend judgment, and this held whether the advice was actively requested or simply displayed. Consequently, participants answered more questions but were correct about a third as often as when AI was unavailable-yet their confidence nearly doubled. Incentivizing accuracy and penalizing inaccuracy led participants to seek and follow AI advice less, answer more accurately, and suspend judgment more often, though still far less than when AI was unavailable. As AI suggestions grow ubiquitous and unsolicited, they may not simply affect answer accuracy; they may even alter the metacognitive threshold at which people decide whether they know enough to answer.

Problem

• AI advice
• metacognition
• judgment suspension
• answer accuracy
• overconfidence

Innovation

• AI advice
• metacognition
• judgment suspension
• overconfidence
• human-AI interaction