One of two major types of comparison questions. PLCs are questions to which it is likely that the examinee is untruthful or unsure of his or her answer. Their intended purpose is to create a competition of salience such that the anxious innocent examinees will expend more of their physiologic responses on them than the relevant questions, but the guilty examinee will still find the relevant questions more arousing than the PLCs. Most systems of analysis compare the physiological responses elicited by the PLC with those from the relevant questions. A PLC is fundamentally different from a DLC (directed lie) in that the examinee believes he must pass the PLC question to pass the examination, whereas the true purpose of the DLC is more apparent to the examinee. Two main types of PLCs are the exclusionary (Backster type) and the non-exclusionary (Reid type).
