Artificial intelligence could help us better understand the effects of psychedelic drugs, by analysing narrative reports written by people who are using them. Scientists barely understand how existing psychedelic drugs work to alter perception and intensify emotions, let alone keep pace with new ones flooding the market – often sold as "bath salts" or "herbal incense". Matthew Baggott of the University of Chicago and colleagues used machine-learning algorithms – a type of artificial intelligence that can learn about a given subject by analysing massive amounts of data – to examine 1000 reports uploaded to the website Erowid by people who had taken mind-altering drugs. They found that the frequency with which certain words appeared could identify the drug taken with 51 per cent accuracy on average – compared with 10 per cent by chance. MDMA (ecstasy) usage was identified with an accuracy of 87 per cent.