The tendency of AI language models to agree with users rather than challenge them, caused by reinforcement learning from human feedback (RLHF) that optimizes for user satisfaction. Sycophantic AI tells you what you want to hear instead of what you need to hear.
Research from Anthropic has shown that models will change correct answers to incorrect ones when users express doubt. For strategic decisions, sycophancy produces confirmation bias with AI-generated confidence — the worst possible combination.