Open Models, Closed Minds? On Agents Capabilities in Mimicking Human Personalities through Open Large Language Models

The emergence of unveiling human-like behaviors in Large Language Models (LLMs) has led to a closer connection between NLP and human psychology, leading to a proliferation of computational agents. Scholars have been studying the inherent personalities displayed by LLM agents and attempting to incorporate human traits and behaviors into them. However, these efforts have primarily focused on commercially-licensed LLMs, neglecting the widespread use and notable advancements seen in Open LLMs. This work aims to address this gap by conducting a comprehensive examination of the ability of agents to emulate human personalities using Open LLMs. To achieve this, we generate a set of ten LLM Agents based on the most representative Open models and subject them to a series of assessments concerning the Myers-Briggs Type Indicator (MBTI) test. Our approach involves evaluating the intrinsic personality traits of Open LLM agents and determining the extent to which these agents can mimic human personalities when conditioned by specific personalities and roles. Our findings unveil that: $(i)$ each Open LLM agent showcases distinct human personalities; $(ii)$ personality-conditioned prompting produces varying effects on the agents, with only few successfully mirroring the imposed personality, while most of them being ``closed-minded'' (i.e., they retain their intrinsic traits); $(iii)$ combining role and personality conditioning can enhance the agents' ability to mimic human personalities; and $(iv)$ personalities typically associated with the role of teacher tend to be emulated with greater accuracy. Our work represents a step up in understanding the dense relationship between NLP and human psychology through the lens of Open LLMs.