Quote from: Dr_Shakalu on May 04, 2008, 04:02 AMTo be successful, a pain countermeasure must be applied timely with the asking of the control questions. Putting pressure on an injured finger could conceivably work, but it has some drawbacks:
1) One wouldn't want it to be the finger to which one of the galvanic skin response attachments will be connected (the index and ring fingers of one hand), as physical pressure against the plates may cause abnormalities in the GSR tracing;
2) If a digital plethysmograph is used as an alternative to a blood pressure cuff, one wouldn't want it to be the finger to which that is attached;
3) Physical movement of a finger might be observed;
4) It requires injuring oneself (and needlessly so).
You'll find a better, alternative pain countermeasure (tongue biting) explained in The Lie Behind the Lie Detector.
. The Doctor.