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Using Large Language Models to Simulate Multiple Humans and Replicate Human Subject Studies

The capacity of LLMs to simulate human behaviour across classic experiments and diverse demographic profiles: model scale, demographic variation, and hyper-accuracy effects.

Research Questions

  1. To what extent can LLMs simulate human behaviour across different populations in experimental settings?
  2. Is it possible to reproduce classic behavioural experiments (Ultimatum Game, Garden Path Sentences, Milgram Shock, Wisdom of Crowds) using LLMs?
  3. How realistically can demographic variation (e.g., name, gender) be reflected in LLM outputs?

Results

  • LLMs successfully replicated several known patterns of human behaviour.
  • Larger models produced responses that were more human-like.
  • Gender-based behavioural differences emerged in LLM outputs (e.g., the chivalry effect: men accepted unfair offers more often when the proposer was female).
  • Newer and more aligned LLMs exhibited hyper-accuracy distortion, performing unrealistically well on certain knowledge tasks.

Findings

  • Behavioural Imitation:
    • Large language models reflected established human behavioural patterns in experiments such as the Ultimatum Game and Garden Path Sentences.
  • Demographic Variation:
    • LLMs were able to simulate behavioural differences based on demographic cues such as name and gender.
  • Hyper-Accuracy:
    • Some models produced answers that were unrealistically accurate relative to typical human performance, failing to mirror real-world human knowledge distributions.
  • Data Contamination Concerns:
    • Because LLMs may have been exposed to these classic experiments during training, questions arise regarding the originality and validity of the reproduced behaviours.
  • Ethical Risks:
    • Simulating harmful experiments such as the Milgram Shock Experiment raises significant ethical concerns.

Scores

  • LLM Models: 5
  • Synthetic Data: 4
  • Method: 4
  • Speed: 3
  • Ethics: 4
  • Accuracy: 3
  • Demographics: 4

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