Dr William Moulton Marston’s work. While his 1915 systolic blood pressure deception test influenced later multi-channel polygraph systems, his most enduring legacy may be the DISC model—a practical map of human behaviour that helps examiners read beyond the charts.
From Blood Pressure to Behavioural Blueprint
In The Emotions of Normal People (1928), Marston outlined four core response tendencies to environmental demands:
- D Dominance: assertive, task-oriented, driven by control.
- I Influence: expressive, people-oriented, motivated by approval.
- S Steadiness: calm, patient, motivated by stability and harmony.
- C Conscientiousness: analytical, detail-focused, driven by correctness.
Polygraph examinations inherently probe sensitive material under structured conditions. Understanding an examinee’s dominant style helps the examiner maintain rapport,
calibrate explanations, and ensure shared definitions during the pre-test—improving the clarity and validity of outcomes.
Why DISC Matters in Polygraph Practice
Modern credibility assessment is more than physiology; it’s the skilled management of emotional and interpersonal dynamics across pre-test, in-test, and post-test phases.
DISC offers a predictive lens for behavioural tendencies that can influence both verbal behaviour and autonomic responses.
| DISC Type | Communication Style | Typical Stress Reaction | Implication for Examination |
|---|---|---|---|
| D — Dominance | Direct, confident, concise | Irritation when control feels limited | Be succinct and fair; avoid over-explaining—emphasise procedure and parity. |
| I — Influence | Talkative, persuasive, rapport-seeking | Charm/avoidance masking anxiety | Keep tone neutral; contain digressions; preserve stimulus salience. |
| S — Steadiness | Calm, agreeable, collaborative | Withdrawal under confrontation | Use steady pacing; offer reassurance; avoid abrupt transitions. |
| C — Conscientiousness | Precise, cautious, methodical | Over-analysis of wording | Define terms explicitly in pre-test; allow processing time; keep phrasing exact. |
Using DISC to Shape Question Design
Polygraph results depend on precise, neutral, mutually understood questions. DISC helps tailor phrasing and delivery—without changing scoring rules or test structure.
D Dominant Examinees
- Prefer direct, concise questions; emphasise fairness and control balance.
- Avoid excessive preambles; confirm shared definitions, then proceed.
- Example: “Before [date], have you ever physically harmed anyone during an argument?”
I Influence-Oriented Examinees
- Rapport is easy; keep tone neutral to preserve stimulus significance.
- Limit digressions; avoid reassuring promises—remain objective.
- Example: “Have you deliberately misled [name] about your involvement in this situation?”
S Steady Examinees
- Provide calm pacing; avoid abrupt or confrontational delivery.
- Use consistent cadence to reduce withdrawal/over-control breathing.
- Example: “Since your relationship began, have you intentionally kept important information from your partner?”
C Conscientious Examinees
- Agree definitions in the pre-test; remove ambiguity from key terms.
- Expect brief processing pauses; don’t rush the response onset.
- Example: “Other than what you have already told me, have you committed any act of physical aggression?”
Chart Interpretation Through a DISC Lens
The chart records physiology; it does not ascribe motive. DISC offers context for understanding why a response was emotionally salient.
- D: Elevated cardio when authority is challenged may reflect control threat rather than deception.
- I: Over-talking and humour can mask anxiety; watch for breathing irregularities during “light” moments.
- S: Withdrawal and rigid pacing can dampen expressiveness; ensure questions remain personally meaningful.
- C: Micro-delays tied to semantic checking; ensure definitions are locked in to prevent artefactual reactions.
Pro Tip: Use behavioural notes from the pre-test (definitions agreed, examples given, tone tolerated) to contextualise any atypical reactivity during scoring.
Ethical & Practical Considerations
DISC profiling must support—not replace—empirical chart evidence. The goal is to humanise delivery, reduce error, and protect examinee dignity while maintaining examiner neutrality.
- Never stereotype or label; treat DISC as a situational guide.
- Keep question structure, cut-scores, and scoring rules unchanged.
- Document any adaptations (pacing, definitions) in the report narrative.
Examiner FAQs
Does DISC change how I score a test?
No. DISC informs delivery (phrasing, pacing, rapport) and context for interpretation notes. Scoring rules and decision criteria remain unchanged.
Is DISC a replacement for a proper pre-test interview?
Never. DISC complements the pre-test by anticipating stress triggers and semantic pitfalls, helping secure shared definitions and stable baselines.
Can tailoring to DISC bias the procedure?
It shouldn’t. Adaptations are procedural (clarity, neutrality, pacing) and should be documented. Avoid suggestive language or unequal treatment.
