The comparison question test: does it work and if so how?

In a mock crime study of the comparison question test (CQT), 35 subjects decided to participate as guilty and 30 as innocent. Two conditions were varied: Explaining the comparison questions in the pretest interview and re-discussing comparison questions between charts. Higher identification rates (approximately 90% for guilty and innocent participants) were achieved in groups with explanation of comparison questions than in groups without explanation. Re-discussing comparison questions had no effect on identification rates. Ratings of subjective stress due to relevant and comparison questions were also obtained and can be seen as indicators of the significance of the questions. The significance of comparison questions was hardly affected by the different testing conditions. When effects are detectable at all, they contradict theoretical expectations in their direction. Results are discussed in terms of the significance of comparison questions used in polygraph testing.