We study the primacy effect in three commercial LLMs: ChatGPT, Gemini and Claude. We do this by repurposing the famous experiment Asch (1946) conducted using human subjects. The experiment is simple, given two candidates with equal descriptions which one is preferred if one description has positive adjectives first before negative ones and another description has negative adjectives followed by positive ones. We test this in two experiments. In one experiment, LLMs are given both candidates simultaneously in the same prompt, and in another experiment, LLMs are given both candidates separately. We test all the models with 200 candidate pairs. We found that, in the first experiment, ChatGPT preferred the candidate with positive adjectives listed first, while Gemini preferred both equally often. Claude refused to make a choice. In the second experiment, ChatGPT and Claude were most likely to rank both candidates equally. In the case where they did not give an equal rating, both showed a clear preference to a candidate that had negative adjectives listed first. Gemini was most likely to prefer a candidate with negative adjectives listed first.

本研究探讨了三种商业大型语言模型（LLMs）中首因效应的影响，包括ChatGPT、Gemini和Claude。研究通过类比Asch（1946）进行的经典实验，发现ChatGPT倾向于优先选择描述中积极形容词在前的候选人，而Gemini表现出对两种候选人的平等偏好，Claude则拒绝选择。

人工智能心理学研究——首因效应是否影响ChatGPT及其他大型语言模型？