The US Department of Defense is looking for ways to develop a lie detector that can be used without the subject knowing they are being assessed. The Remote Personnel Assessment device will also be used to pinpoint fighters hiding in a combat zone, or to spot signs of stress that might mark someone out as a terrorist or suicide bomber.

Contractors are being given until 13 January to suggest ways to develop the RPA, which will use microwave or laser beams reflected off a subject’s skin to assess various physiological parameters. The device will train a beam on “moving and non-cooperative subjects” and use the reflected signal to calculate their pulse, respiration rate and galvanic skin response.

The RPA will also be used as a “remote or concealed lie detector during prisoner interrogation”.

But finding ways to fulfil the brief will be a challenge, says Robert Prance, from the University of Sussex, UK. “They might capture breathing rate with an infrared laser that senses chest vibration, but how they will measure a pulse through clothes, for instance, is a very big question.”

If the RPA is ever produced, it is likely to prove controversial.

Via New Scientist.