Will there ever be a reliable lie detector?

For as long as we have been human we have looked for some way of telling when we are being told the truth. We tried dunking witches, only to find that buoyancy is not connected to the supernatural. We tried torture, but discovered that people will eventually say just about anything to make it stop. We experimented with scopolamine and sodium pentathol, to learn that ‘truth serums’ do little more than make their targets susceptible to suggestion. And we’re still trying – with scientists pushing MRI scans and ECGs alongside AI as a ‘brain fingerprinting’ technique. The jury is out as to whether the latest ideas will prove any more reliable than those that went before.

It was investigating brain fingerprinting that prompted Amit Katwala, a senior contributor to WIRED, to write Tremors in the Blood – named for the 1730 quote from the novelist and spy Daniel Defoe, who believed guilt always caused such a tremble. It is a shame we have to wait until the ‘Coda’ to learn that it was the modern search for an infallible truth machine that inspired Katwala, as what makes up the rest of the book is a thrilling, page-turning near-novelisation of the development of what we now know as the polygraph.

We begin in early 20th-century America, first in Berkeley, California, with August Vollmer, the man credited as the father of modern American policing, and observe the efforts of an uneducated boy made good to bring scientific method to a police force more used to dispensing justice by the ‘third degree’ (administered usually by beatings to the stomach). We are then taken to Chicago, following two of Vollmer’s protégés as they invent and ‘perfect’ what is initially named the ‘cardio-pneumo-psychograph’.