Optimizing auxiliary agent attributes beyond exogenous variables in LLM-powered simulations
Develop an optimization framework for selecting and endowing additional agent attributes—such as demographics, personalities, and other traits—beyond the structural causal model’s exogenous variables for large language model–powered agents, so as to improve simulation fidelity while avoiding redundancy and unintended interactions.
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However, it is unclear how to optimize this process.
The composition of a persona is of particular note; it is not clear which attributes should make up a persona and whether this selection should be determined based on an a priori theory, constructed in a data-driven manner, or a combination of both.
Two directions we have not explored are: (i) personality-conditioned harnesses~\citep{chi2024amongagents} that condition the agent's chat and plan style on an assigned imposter or crewmate persona, which could decouple deception strategy from the underlying VLM's default style; and (ii) meta-harness optimization~\citep{lee2026metaharness} that searches over the harness implementation itself rather than the five hand-specified axes. Both are natural follow-ups to the present per-axis ablation and we leave them to future work.
Future work should investigate when behavioural associations transfer across tasks and models, and whether combining multiple empirically grounded individual characteristics can reproduce richer forms of human behavioural diversity.
The life simulator writes English conversations, and the lives it writes follow the generating LLMs' notion of how a typical life unfolds. Associations that are specific to a culture, a community or an individual may therefore be learned less well, and extending the simulator to other languages and to more diverse lives is left to future work.
This process also produces two other traits: hostile non-cooperation and mental and physical impairment. However, due to their complexity, high stakes, and relative rarity, we leave the simulation of these traits to future work.