Lie Detector

We got the electronic kit out on Tuesday. We haven't used it for a few years, so after a quick recap, and making a few circuits in parallel and series, the girls made a lie detector.
The circuit is left open and completed by the test person. The theory is that if the person tells a lie, their hands will be become clammy and damp and so increase conductivity into the skin and complete the circuit and so light will light up.

We had lots of fun teasing each other with funny questions, and then closely looking to see if the light was even slightly glowing. Not sure if this would have been accepted as evidence in court! Are you brave enough to take the lie detector challenge?