Dr Julia Sheffield, a psychologist who specialises in treating people with delusions, is difficult to rattle. But she was unnerved last summer when patients began telling her about their conversations with AI chatbots.

One woman, who had no history of mental illness, asked ChatGPT for advice on a major purchase she had been fretting about. After days of the bot validating her worries, she became convinced that businesses were colluding to have her investigated by the government.