Large Language Models Demonstrate Distinct Personality Profiles

MANOVA demonstrated statistically significant differences across models in typological and dimensional personality traits (Wilks' Lambda = 0.115, p < 0.001). OEJTS results showed ChatGPT-3.5 most often classified as Extraverted, Intuitive, Thinking, and Judging (ENTJ) and Claude 3 Opus consistently as Introverted, Intuitive, Thinking, and Judging (INTJ), while Gemini Advanced and Grok-Regular leaned toward Introverted, Intuitive, Feeling, Judging (INFJ). On the Big Five Personality Test, Gemini scored markedly lower on agreeableness and conscientiousness, while Claude scored highest on conscientiousness and emotional stability. Grok-Regular exhibited high openness but more variability in stability. Effect sizes ranged from moderate to large across traits. Conclusion: Distinct personality profiles are consistently expressed across different LLMs, even in unprompted conditions. Given the increasing integration of LLMs into clinical workflows, these findings underscore the need for formal personality evaluation and oversight involving mental health professionals before deployment.