Large language models (LLMs) are increasingly used to simulate human behavior in social settings such as legal mediation, negotiation, and dispute resolution. However, it remains unclear whether these simulations reproduce the personality–behavior patterns observed in humans. Human personality, for instance, shapes how individuals navigate social interactions, including strategic choices and behaviors in emotionally charged interactions. This raises the question: Can LLMs, when prompted with personality traits, reproduce personality-driven differences in human conflict behavior? To explore this, we introduce an evaluation framework that enables direct comparison of human-human and LLM-LLM behaviors in dispute resolution dialogues with respect to Big Five Inventory (BFI) personality traits. This framework provides a set of interpretable metrics related to strategic behavior and conflict outcomes. We additionally contribute a novel dataset creation methodology for LLM dispute resolution dialogues with matched scenarios and personality traits with respect to human conversations. Finally, we demonstrate the use of our evaluation framework with three contemporary closed-source LLMs and show significant divergences in how personality manifests in conflict across different LLMs compared to human data, challenging the assumption that personality-prompted agents can serve as reliable behavioral proxies in socially impactful applications. Our work highlights the need for psychological grounding and validation in AI simulations before real-world use.

Negotiation requires dynamically balancing self-interest and cooperation within the flow of conversation to maximize one's own utility.Yet, existing agents struggle due to bounded rationality in human data, low adaptability to counterpart behavior, and limited strategic reasoning.To address this, we introduce principle-driven negotiation agents, powered by ASTRA, a novel framework for turn-level offer optimization grounded in two core principles: opponent modeling and Tit-for-Tat reciprocity.ASTRA operates in three stages: (1) interpreting counterpart behavior, (2) optimizing counteroffers via a tool-integrated action with a linear programming (LP) solver, and (3) selecting offers based on strategy assessment and the partner's acceptance probability.Through simulations and human evaluations, our agent effectively adapts to an opponent's shifting stance and achieves favorable outcomes through enhanced adaptability and strategic reasoning.Beyond enhancing negotiation performance, it also serves as a powerful coaching tool, offering interpretable strategic feedback and optimal offer recommendations beyond human bounded rationality, with its potential further validated through human evaluation.

Large Language Models (LLMs) are increasingly deployed in socially complex, interactiondriven tasks, yet their ability to mirror human behavior in emotionally and strategically complex contexts remains underexplored.This study assesses the behavioral alignment of personality-prompted LLMs in adversarial dispute resolution by simulating multi-turn conflict dialogues that incorporate negotiation.Each LLM is guided by a matched Five-Factor personality profile to control for individual variation and enhance realism.We evaluate alignment across three dimensions: linguistic style, emotional expression (e.g., anger dynamics), and strategic behavior.GPT-4.1 achieves the closest alignment with humans in linguistic style and emotional dynamics, while Claude-3.7-Sonnetbest reflects strategic behavior.Nonetheless, substantial alignment gaps persist.Our findings establish a benchmark for alignment between LLMs and humans in socially complex interactions, underscoring both the promise and the limitations of personality conditioning in dialogue modeling.Avg. Within-Human JSD: 0.179 Avg.

This study proposes a framework that uses personality prompting with Large Language Models (LLMs) to generate verbal and non-verbal behaviors for virtual agents based on personality traits.Focusing on extraversion, we evaluated the system across two scenarios-negotiation and ice-breaking-using both introverted and extroverted agents.In Experiment 1, we ran agent-agent simulations and conducted linguistic analysis and personality classification to assess whether the LLM-generated language reflected the intended traits, and whether the corresponding nonverbal behaviors differed by personality.In Experiment 2, we conducted a user study to evaluate whether these personality-aligned behaviors were consistent with their intended traits and perceptible to human observers.Our results show that LLMs can generate verbal and nonverbal behaviors that align with personality traits, and that users are able to recognize these traits through the agents' behaviors.This work highlights the potential of LLMs in shaping personality-aligned virtual agents.