The Event Knowledge Test (EKT) in Polygraph Examination (common notice of tactics)

This paper describes the Event Knowledge Test (EKT), a modification of the Concealed Information Test developed and widely used in Lithuania since 1992 for criminal investigations. The EKT tests whether suspects possess knowledge of crime details that only someone present at the scene would know, representing an alternative to the Comparison Question Test dominant in Western practice.

The EKT employs a concealed information testing paradigm using multiple-choice alternatives about specific crime details, with questions arranged progressively from least to most significant to maximize physiological responsiveness.

The Event Knowledge Test represents a distinctive Lithuanian approach to polygraph examination, serving as a modification of the Concealed Information Test for criminal investigations. The technique employs crime-specific questions arranged progressively from least to most significant, presented without prior introduction to maintain novelty and maximize orienting responses. Field applications demonstrate high magnitude physiological differentiation between relevant and irrelevant items, though interpretation can be challenging due to high stress levels. The EKT has successfully revealed crucial information in serious criminal cases, including a 2007 homicide investigation involving a missing car salesman.

The EKT provides an alternative to Western CQT approaches, offering practical investigative value in revealing perpetrator knowledge of crime details. However, the high stress levels it generates present interpretative challenges that require specialized expertise for accurate chart analysis.

Background & Context

The Event Knowledge Test (EKT) represents a distinctive approach to polygraph examination developed and refined in Lithuania, where it has been widely used since polygraph testing began in 1992. In Lithuania, law enforcement has utilized the Event Knowledge Test as a modification of the Concealed Information Test (CIT) in criminal investigations. Unlike the Comparison Question Test (CQT) dominant in Western polygraph practice, tests based on a comparison-relevant question system are not popular in Lithuania.

The EKT emerged from a practical need for investigative tools that could reveal crime-specific knowledge possessed only by perpetrators and investigators. The EKT has been widely available in Lithuania and has revealed important circumstances of crimes, helping police investigate them. This technique fills a critical gap in criminal investigations by testing whether suspects possess knowledge of details that only someone present at a crime scene would know.

The development of EKT tactics represents an evolution from traditional Guilty Knowledge Test (GKT) methodology, adapted specifically for field use in criminal investigations. The 2008 paper on "common notice of tactics" provided essential procedural guidance for practitioners implementing this technique in real-world investigative settings.

Research Design & Methodology

The EKT employs a concealed information testing paradigm where examinees are presented with multiple-choice alternatives about specific crime details. One of the main requirements in EKT tactics is that questions are arranged from the least to the most significant one, though this is only a trend in actual examinations as the examiner's opinion about significance may vary. This progressive structure aims to maximize physiological responsiveness as the examination proceeds.

Key methodological features of the EKT include:

• Questions are not introduced to examinees before the tests, preserving the novelty of stimuli
• Questions are usually not repeated during the examination, maintaining high orienting response levels
• The procedure is briefly introduced to the examinee before examination to minimize fatigue while maintaining sufficient instruction
• Questions focus on crime-specific details known only to investigators and perpetrators

The technique relies heavily on the orienting reflex (OR) to novel, significant stimuli. The theoretical foundation draws on psychophysiological principles including Pavlovian conditioning, Sokolov's orienting reflex theory, and theories of emotional arousal. Standard polygraph sensors measure electrodermal activity (EDA), cardiovascular responses, and respiratory patterns during questioning.

Results & Key Findings

The EKT demonstrates high magnitude of relative responses in field examinations. The magnitude of response remains high or very high when resorting to the EKT, indicating strong physiological differentiation between relevant and irrelevant items.

However, the technique presents specific interpretative challenges:

• A potential problem of the EKT is the very high level of the subject's stress, which makes interpreting the charts very difficult
• The novelty factor creates stronger initial responses but habituation is reduced due to non-repetition of questions
• Field validation studies demonstrated the technique's ability to reveal crucial investigative information in actual criminal cases

The EKT has been successfully applied in serious criminal investigations, including homicide cases. A psychophysiological test by polygraph revealed important circumstances of a crime when a 29-year-old car salesman disappeared in mysterious circumstances in September 2007, and his car was found after a few days. This real-world application demonstrated the technique's utility in generating investigative leads.

Discussion & Significance

The EKT represents an important alternative to Western CQT-based approaches, particularly for jurisdictions where comparison question methods face legal or cultural barriers. The technique's focus on information detection rather than lie detection addresses some of the theoretical criticisms leveled at traditional polygraph methods. By identifying who possesses specific crime knowledge, the EKT provides investigative value even in legal systems skeptical of deception detection.

The high stress levels generated by EKT procedures—while creating interpretative challenges—may also enhance the technique's sensitivity. The authors' subsequent research explored optimal conditions for polygraph examinations, examining factors like fear, habituation, fatigue, novelty, and significance. Reviews of Lithuanian field polygraph charts from 2008-2012 found individual variation in physiological patterns, leading researchers to believe it is too early to apply rigid models distinguishing orienting response from defensive response in field examinations.

The widespread adoption of EKT in Lithuania contributed to European polygraph diversity, demonstrating that effective polygraph methodology need not follow the American CQT model exclusively. This work influenced subsequent developments in concealed information testing across Eastern Europe and contributed to international dialogue about optimal polygraph techniques.

Limitations & Considerations

The primary limitation acknowledged by researchers is the interpretative difficulty created by extremely high stress levels in examinees. The very high level of subject stress makes interpreting the charts very difficult, potentially leading to ambiguous results or increased inconclusives. This challenge is inherent to the EKT's design—maximizing response magnitude through novelty and significance necessarily elevates overall arousal.

• Individual differences in stress tolerance and physiological responsiveness complicate standardized interpretation
• The non-repetition of questions prevents within-examination reliability checks common in other techniques
• Field conditions introduce uncontrolled variables that may affect chart quality and interpretation
• Results of psychophysiological tests and their conclusions are difficult to prove in courts in Lithuania's legal system

The technique requires substantial examiner expertise and familiarity with case facts to construct effective question sequences. Unlike standardized CQT formats, EKT implementation demands creative adaptation to each investigation's unique circumstances.

Practical Applications

The EKT serves primarily as an investigative tool in criminal cases, particularly where suspects deny knowledge of crime details. Law enforcement can use EKT results to prioritize investigative resources, identify promising leads, and guide interview strategies. The technique proves especially valuable in cases with limited physical evidence but multiple suspects—determining who possesses crime-scene knowledge can dramatically narrow the investigation.

For polygraph examiners, the EKT offers an alternative when comparison question techniques are unsuitable or legally problematic. The technique's reliance on information detection rather than explicit lie-truth judgments may face fewer admissibility challenges in some jurisdictions. However, practitioners must carefully manage examinee stress levels and develop sophisticated chart interpretation skills to handle the high-arousal physiological patterns characteristic of EKT examinations. The work by Saldžiūnas and Kovalenko provided essential tactical guidance for implementing this technique effectively in real-world criminal investigations.