The paper introduces the concept of social simulacra—large, synthetic populations of personas, posts, and replies generated by large language models—to support the design and evaluation of social computing systems. The authors present SimReddit, a prototype tool that leverages GPT‑3 to (1) GENERATE realistic user profiles and content, (2) explore WHAT‑IF scenarios by editing community rules or moderation policies and instantly observing simulated behavioral changes, and (3) create MULTIVERSE collections of alternative community evolutions for comparative analysis. The work details prompting strategies for scaling persona creation, methods for chaining prompts to produce coherent thread‑level interactions, and mechanisms for controlling demographic and behavioral attributes. Two empirical studies assess (a) technical plausibility—human judges rate generated posts and replies as plausibly human‑written—and (b) design utility—professional designers use SimReddit to iterate on moderation policies, reporting that the tool helped surface unintended consequences and refine community guidelines. The authors discuss ethical considerations, limitations of language‑model‑based simulation, and future directions such as integrating multimodal content, richer behavioral models, and user‑in‑the‑loop validation. Overall, the paper argues that synthetic social simulacra can accelerate early‑stage prototyping, reduce reliance on costly live deployments, and enable systematic exploration of design spaces in social computing.
Topics
Social Simulacra: Synthetic Populations as Design Prototypes
Introduces the notion of social simulacra—large, AI‑generated collections of personas, posts, and replies that emulate real‑world community dynamics—positioned as reusable design artifacts for exploring social computing systems.
SimReddit: Architecture and Core Functionalities
Describes the SimReddit prototype, detailing its three primary modes—GENERATE (persona and content creation), WHAT‑IF (policy editing with instant behavioral simulation), and MULTIVERSE (parallel community evolutions for comparative analysis)—and the overall system pipeline.