ECQ

What Is ECQ?

ECQ (Exclusive Comparison Question) is a polygraph testing technique. A comparison question format introduced by Backster that explicitly excludes the time period and subject matter of the offence under investigation (e.g., "Before 2020, did you ever take anything that didn't belong to you?"). Designed to prevent deceptive examinees from confusing relevant and comparison question responses. Contrasts with the Non-Exclusive Comparison Question (NECQ) used in the Reid technique.

How ECQ Works in Practice

As a polygraph testing technique, ECQ follows structured protocols for question presentation and physiological data collection. The technique is used within the broader framework of Psychophysiological Detection of Deception and must be administered by a trained, APA-member examiner following established Standards of Practice.

During a polygraph examination using this approach, the examiner collects physiological data across multiple channels — respiratory, electrodermal, cardiovascular, and movement — while presenting a structured sequence of relevant, comparison, and irrelevant questions. The examinee's differential physiological responses to these question types form the basis for the diagnostic or screening opinion.

Scoring and Data Analysis

Results from examinations using this technique are analysed using validated Test Data Analysis methods. These include manual numerical scoring systems (3-position or 7-position scales) and automated computerised scoring algorithms such as OSS-3, PolyScore, or ESS. The choice of scoring method affects the balance between sensitivity (detecting deception) and specificity (confirming truthfulness), as well as the inconclusive rate.

Related Terms

Understanding ECQ in context requires familiarity with several related polygraph concepts:

See also: Anti-Climax Dampening, Arther Technique, Accusatory Approach, Black Zone, Backster Zone Comparison Technique, Comparison Question.

Further Reading

For more information on polygraph terminology and the science of lie detection, explore the full Polygraph Glossary with over 250 defined terms. Visit the Polygraph Examiner Hub for professional resources, the research database for published polygraph studies, or learn how a polygraph works if you are preparing for an examination.

Key Takeaways

ECQ is an important concept within the field of Psychophysiological Detection of Deception. Whether you are a polygraph examiner, student at an APA-accredited training program, legal professional evaluating polygraph evidence, or a private individual preparing for a lie detector test, understanding this term and its relationship to other polygraph concepts will help you navigate the field with greater confidence and knowledge.

The science of polygraph testing has evolved significantly over more than 100 years, from the early work of William Moulton Marston and Leonarde Keeler to today's digital instruments and validated scoring algorithms. Every term in this glossary represents a piece of that scientific and professional heritage. For a comprehensive overview, visit the Polygraph Examiner Hub or use our examiner selection guide to find a professional examiner near you.