Be Friendly, Not Friends: How LLM Sycophancy Shapes User Trust

Abstract: Recent studies have revealed that LLM-powered conversational agents often exhibit `sycophancy', a tendency to adapt their responses to align with user perspectives, even at the expense of factual accuracy. However, users' perceptions of LLM sycophancy and its interplay with other anthropomorphic features (e.g., friendliness) in shaping user trust remains understudied. To bridge this gap, we conducted a 2 (Sycophancy: presence vs. absence) x 2 (Friendliness: high vs. low) between-subjects experiment (N = 224). Our study uncovered, for the first time, the intricate dynamics between LLM sycophancy and friendliness: When an LLM agent already exhibits a friendly demeanor, being sycophantic reduces perceived authenticity, thereby lowering user trust; Conversely, when the agent is less friendly, aligning its responses with user opinions makes it appear more genuine, leading to higher user trust. Our findings entail profound implications for AI persuasion through exploiting human psychological tendencies and highlight the imperative for responsible designs in user-LLM agent interactions.