Lie Detector Device
Puzzle 7 of Hellos and Goodbyes Easy Pack
Question is: Lie Detector Device
and the answer is: POLYGRAPH
Word Meaning:
POLYGRAPH — A device which measures and records several physiological variables such as blood pressure, heart rate, respiration and skin conductivity while a series of questions is being posed to a subject, in an attempt to detect deception.
Definitions from Wiktionary.