category bar

What Is a Category Bar?

A category bar is a visual marker or notation system used on polygraph charts to indicate the category or type of each question as it appears in the test sequence. Category bars allow examiners and quality control reviewers to quickly identify which questions are relevant, comparison, irrelevant, or symptomatic, ensuring proper pairing of questions at each analysis spot during scoring.

Function in Chart Analysis

During numerical scoring, the examiner must correctly identify which question type each response belongs to before assigning scores. Category bars provide this information at a glance, preventing errors such as comparing two relevant questions against each other or misidentifying an irrelevant question as a comparison. In digital polygraph systems, category information is typically embedded in the chart data and displayed automatically.

Types of Category Designations

Standard category designations used across most validated techniques include markers for: irrelevant questions (I), sacrifice relevant questions (SR), symptomatic questions (S), relevant questions (R — often numbered R1, R2, etc.), and comparison questions (C — often numbered C1, C2, etc.). The specific question sequence and category assignments vary by technique — the Backster Zone Comparison, Utah Probable Lie, and Directed Lie Test each use different question sequences with different category assignments.

Role in Quality Control

During blind chart analysis and quality control review, category bars are essential for the reviewer to correctly apply scoring rules. The reviewer needs to know the question categories and the technique-specific pairing rules (such as the Either-Or Rule) to properly score each analysis spot. Incorrect category marking could lead to scoring errors that invalidate the review.

Related Chart Annotations

Category bars are part of the broader system of chart markings that document the examination. Other annotations include event markers, time bars, place bars, stimulus markers, and movement notations.