PHAnToM: Personality Has An Effect on Theory-of-Mind Reasoning in Large Language Models

Recent advances in large language models (LLMs) demonstrate that their capabilities are comparable, or even superior, to humans in many tasks in natural language processing. Despite this progress, LLMs are still inadequate at social-cognitive reasoning, which humans are naturally good at. Drawing inspiration from psychological research on the links between certain personality traits and Theory-of-Mind (ToM) reasoning, and from prompt engineering research on the hyper-sensitivity of prompts in affecting LLMs capabilities, this study investigates how inducing personalities in LLMs using prompts affects their ToM reasoning capabilities. Our findings show that certain induced personalities can significantly affect the LLMs' reasoning capabilities in three different ToM tasks. In particular, traits from the Dark Triad have a larger variable effect on LLMs like GPT-3.5, Llama 2, and Mistral across the different ToM tasks. We find that LLMs that exhibit a higher variance across personality prompts in ToM also tends to be more controllable in personality tests: personality traits in LLMs like Figure 1: Overview of PHAnToM. Our work investigates GPT-3.5, Llama 2 and Mistral can be controllably how eight different personality prompts (Big Five adjusted through our personality prompts. OCEAN and Dark Triad) affects LLMs' ability to perform In today's landscape where role-play is a common three theory-of-mind reasoning tasks (Information strategy when using LLMs, our research Access (IA), Answerability (AA), and Belief Understanding highlights the need for caution, as models that (BU)).