More Intense Than Westworld: 8.3 Billion 'Hosts' Go Online

A coalition of top institutions including Harvard, MIT, and Stanford has launched MatrAIx, an AI user simulation system with 8.3 billion digital personas, nearly matching the world's population. Built on 1,290 personality dimensions and powered by models like GPT-5.5 and Claude Opus 4.8, it aims to simulate user behavior at scale for product testing. In 18,189 tests, 91.5% of agent behaviors matched their assigned personality traits.