Polygraph Glossary Scoring

Kircher Features

Definition

A set of physiological response features first described by researchers at the University of Utah in the 1980s. Include the amplitude of increase for electrodermal and cardiovascular activity, and reduction of respiratory activity. Kircher features form the basis for most modern polygraph scoring algorithms including OSS-3, PolyScore, and ESS. Can be extracted both visually and by automated computer methods.

What Is Kircher Features?

Kircher Features is a polygraph scoring concept. A set of physiological response features first described by researchers at the University of Utah in the 1980s. Include the amplitude of increase for electrodermal and cardiovascular activity, and reduction of respiratory activity. Kircher features form the basis for most modern polygraph scoring algorithms including OSS-3, PolyScore, and ESS. Can be extracted both visually and by automated computer methods.

Role of Kircher Features in Polygraph Scoring

Scoring methodology is one of the most critical factors affecting polygraph accuracy. The evolution from subjective global evaluation to structured numerical scoring and automated algorithms has significantly improved the reliability and reproducibility of polygraph results, as measured by interrater reliability studies.

Modern scoring approaches analyse physiological responses across multiple channels — electrodermal activity (considered the most diagnostically powerful single channel), respiratory patterns, and cardiovascular changes — using validated Kircher features that have demonstrated replicable diagnostic value across decades of research.

Practical Application

APA Standards of Practice require the use of validated scoring methods for all diagnostic and screening polygraph examinations. The choice of scoring system directly affects the cut-scores applied for classification decisions (Deception Indicated, No Deception Indicated, or Inconclusive) and the overall balance between false positives and false negatives.

Related Terms

Understanding Kircher Features in context requires familiarity with several related polygraph concepts:

Key Takeaways

Kircher Features 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.

Cross-references

More scoring terms in this glossary

signal detection theory Signal detection theory (SDT) quantifies a test's capacity to discriminate between signal (deception) and noise (trut... TDATest Data Analysis The process of analysing recorded physiological data from a polygraph examination to reach a diagnostic or screening ... Effect Size A statistical measure of the magnitude of difference between physiological responses to relevant versus comparison qu... Grand Total Rule A decision rule used in the Empirical Scoring System (ESS) where the sum of all comparison-to-relevant scores across ... Overfitting A statistical problem where a scoring algorithm performs very well on training data but poorly on new data. Occurs wh... Adaptive Questioning A testing approach in which subsequent questions or test presentations are adjusted based on the examinee's physiolog...

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