Do our eyes betray us when we lie? The US government hopes to find out.
In Ridley Scott's 1982 sci-fi classic, Bladerunner, the police have a problem. The wayward androids they are pursuing behave so much like humans, they have a tough time telling them apart.
They turn to the Voight-Kampff test, a futuristic version of the age-old polygraph, to help them out. During the test, subjects are grilled with a list of questions, while their physiology is monitored. In particular, the test looks for abnormal eye responses that might indicate the subject isn't human.
The test is far from perfect, and no doubt there will be teething troubles that beset the development of a similar test the US department of homeland security is looking for help in making.