the most commonly used technique in specific incident investigations is the controlled question test (CQT), in which the subject responds to a series of questions relevant and not relevant to the incident. The guilty knowledge test (GKT) requires the subject to respond to a series of questions about a crime posed in multiple-choice format. Field and laboratory studies on the validity of CQT results have produced mixed results: some have found the CQT accurate with both guilty and innocent subjects, while others have found it quite fallible and strongly biased against the innocent. Although the GKT has been found to be accurate in laboratory studies and should provide safeguards for the innocent, no field research has been done; and it is rarely used. Uses for polygraph tests have included testing of witnesses, suspects, and complainants; employment screening; and deterrence of employee theft and misconduct. 63 references.