This study examines how model-specific characteristics of Large Language Model (LLM) agents, including internal alignment, shape the effect of memory on their collective and cooperative dynamics in a multi-agent system. To this end, we extend the Social Particle Swarm (SPS) model, in which agents move in a two-dimensional space and play the Prisoner's Dilemma with neighboring agents, by replacing its rule-based agents with LLM agents endowed with Big Five personality scores and varying memory lengths. Using Gemini-2.0-Flash, we find that memory length is a critical parameter governing collective behavior: even a minimal memory drastically suppressed cooperation, transitioning the system from stable cooperative clusters through cyclical formation and collapse of clusters to a state of scattered defection as memory length increased. Big Five personality traits correlated with agent behaviors in partial agreement with findings from experiments with human participants, supporting the validity of the model. Comparative experiments using Gemma~3:4b revealed the opposite trend: longer memory promoted cooperation, accompanied by the formation of dense cooperative clusters. Sentiment analysis of agents' reasoning texts showed that Gemini interprets memory increasingly negatively as its length grows, while Gemma interprets it less negatively, and that this difference persists in the early phase of experiments before the macro-level dynamics converge. These results suggest that model-specific characteristics of LLMs, potentially including alignment, play a fundamental role in determining emergent social behavior in Generative Agent-Based Modeling, and provide a micro-level cognitive account of the contradictions found in prior work on memory and cooperation.

翻译：本研究探究了大语言模型（LLM）代理的模型特有特性（包括内部对齐）如何塑造记忆对其在多智能体系统中集体与协作动力学的影响。为此，我们扩展了社会粒子群（SPS）模型——在该模型中，代理在二维空间中运动并与邻居进行囚徒困境博弈——将其基于规则的代理替换为具有大五人格评分和可变记忆长度的LLM代理。利用Gemini-2.0-Flash，我们发现记忆长度是调控集体行为的关键参数：即使是最低限度的记忆也急剧抑制了合作，随着记忆长度增加，系统从稳定的合作集群，经过集群的周期性形成与崩溃，转变为散布的背叛状态。大五人格特质与代理行为的关联部分与人类参与者实验结果一致，支持了模型的有效性。使用Gemma~3:4b进行的对比实验揭示了相反趋势：更长的记忆促进了合作，并伴随密集合作集群的形成。对代理推理文本的情感分析显示，Gemini对记忆的解读随长度增加而愈发负面，而Gemma的解读则负面程度较低；这种差异在实验初期、宏观动态收敛之前便已存在。这些结果表明，LLM的模型特有特性（可能包括对齐）在生成式基于代理建模中决定涌现的社会行为方面发挥着根本作用，并为先前关于记忆与合作研究的矛盾之处提供了微观层面的认知解释。