Converus’s technology, EyeDetect, has been used by FedEx in Panama and Uber in Mexico to screen out drivers with criminal histories, and by the credit ratings agency Experian, which tests its staff in Colombia to make sure they aren’t manipulating the company’s database to secure loans for family members. In the UK, Northumbria police are carrying out a pilot scheme that uses EyeDetect to measure the rehabilitation of sex offenders. Other EyeDetect customers include the government of Afghanistan, McDonald’s and dozens of local police departments in the US. Soon, large-scale lie-detection programmes could be coming to the borders of the US and the European Union, where they would flag potentially deceptive travellers for further questioning.

But as tools such as EyeDetect infiltrate more and more areas of public and private life, there are urgent questions to be answered about their scientific validity and ethical use. In our age of high surveillance and anxieties about all-powerful AIs, the idea that a machine could read our most personal thoughts feels more plausible than ever to us as individuals, and to the governments and corporations funding the new wave of lie-detection research. But what if states and employers come to believe in the power of a lie-detection technology that proves to be deeply biased – or that doesn’t actually work?

And what do we do with these technologies if they do succeed? A machine that reliably sorts truth from falsehood could have profound implications for human conduct.