Companies could soon test products on billions of fake customers. Harvard and MIT built MatrAIx, a system based on 8.3 billion AI personas.
Each persona can have 1,290 different attributes. Then researchers turn them into agents and let them interact with real products.
They can: • Shop • Take surveys • Use apps • Talk to chatbots • React to changes The team ran 18,189 experiments using different AI models.
And the results exposed something important. The AI model itself changes the behavior.
For the same price increase:
GPT-5.5 → 98.3% hesitated Claude Opus 4.8 → 27% hesitated Same cohort. Same scenario.
Completely different reaction.