“He used to advise trainees to clench their anus but has since concluded that terrifying mental imagery works better.”
When you get a control question, which is more general, envision the scariest thing you can in order to trigger physiological distress; the polygraph’s tubes around your chest measure breathing, the arm cuff monitors heart rate and electrodes attached to you fingertips detect perspiration. What is your greatest fear? Falling? Drowning? Being buried alive? “Picture that,” Williams says.
— How to Beat a Polygraph Test, by Malia Wollan.
Short but interesting read. Reading so much from the NY Times lately, I am seriously considering a subscription.