Lie Detection Truth Verification Veracity assessment Psycho physiological stress detection Also known as:
History of separating truth from deception • In ancient China the suspect held a spoonful of rice in his or her mouth during a prosecutor's speech. Since salivation was believed to cease at times of emotional anxiety, the person was considered guilty if by the end of that speech the rice remained dry. • For hundreds of years pulse has also been used to detect deception. A nobleman suspected his wife of infidelity and informed his advisor of this. A test was arranged at dinner where the advisor was seated next to the nobleman’s wife. While conversing with her he casually laid his hand upon her wrist and mentioned the name of the person suspected by the nobleman. The lady’s pulse suddenly quickened while it had not when mentioning her husband’s name. A confession was later obtained. (Gesta Romanorum 1906)
Development • The idea that lying produces physical side-effects (psycho-physiological analogues) has long been claimed. • Mosso, with strong encouragement by his mentor Lombroso, used a “plethysmograph” (developed by Francis Franke) that measures blood pressure and volume, to determine the influence of emotion and fear on cardio activity and respiration. • Lombroso actually applied the experimental use of the plethysmograph and spygmograph during interrogations. • Adamkiewicz’s experimental proof that the secretion of sweat is closely linked to psychological processes, lead Sticker to experiment with the galvanic skin phenomenon and the development of the first psycho-galvanometer. • With the combination of the three systems: pneumograph; psycho-galvanometer and cardiospysmograph, by Arthur MacDonald, the Polygraph was born.
Other truth verification research • In 1964, Charles R. McQuiston together with two friends, Wilson Ford and Alan Bell, developed the first prototype of his “Psychological Stress Evaluator”. The PSE relied on measuring stress-induced changes to the “muscle micro-tremor (8-12 Hz)” as displayed in involuntary changes in the voice. The theory of the micro tremor comes from Lippold who did indicate that stress causes the muscles to tremble in the 8-12 Hz frequency range. • This muscle tremor then reflects on the vocal cords, being muscles themselves. • In less than one century the search for and studies on truth verification developed four main methods: the polygraph, the voice stress analyzer, psychological profiling and truth serum.
The Latest and the Future • In the middle 90’s, several publications “crucified” the “micro tremor” technologies. To analyze these, one obviously has to detect and record them. Normally available hardware just doesn’t “see” 8-12 Hz. • In 1998, Amir Liberman, Israel, developed and presented for research “Layered Voice Analysis”, a technology looking at the whole “hearable” spectrum of the voice. This new technology does not depend on any micro tremors and can use any microphone and telephone line for data gathering. • Several other technologies are in development, such as “iris control”, infrared face scanning and the latest: MRI (magnetic resonance imaging”. • At present, polygraph, VSA (aka PSE, CVSA) and LVA (and related technologies) are the most commonly used psycho physiological veracity assessment tools, world wide.
Psychophysiology • The branch of psychology that is concerned with the physiological bases of psychological processes • Study of the interface of mind and body • Looks at the way psychological activities produce physiological responses • Psycho physiological measures are used to study emotion and attention responses in response to stimuli (for example: a question asked)
Lying and stress • The act of lying causes stress • Lie-detection consists mainly of stress detection. • Lie-detection systems use physiological data. • The data relies on detecting the stress that a person experiences when he is lying.
Nobody can live without a certain amount of stress. Crossing a road, trying to catch a train, or simply a feeling of joy is enough to 'trigger' the stress mechanism. Stress is not necessarily bad; stress is part of life as every emotion, every activity causes stress (R. D. Vooijs - 2004) • Although stress is also associated with positive emotions, lie detection focuses on negative stress such as stress caused by anger or fear.
What is stress? • everybody has a general notion of what is stress, however, the wide use of the term 'stress' has led to a multitude of different definitions • general consensus: the stress concept involves external or internal stimulation of the organism, which upsets its internal balance (homeostasis). • general agreement that stress involves a series of physiological and behavioral changes which prepare the organism for the appropriate coping response, or, the fight or flight mode.
The effects of stress • (very complex: only the physiological responses will be discussed) • Physiological effects: • induced by the ANS, • operates involuntary • can (normally) not be brought under conscious control
Effects of stress on speech Lips, tongue, jaw and pharynx tension and movement Regularity depth Sub glottal air pressure Height of Larynx Tension and shape of folds Regularity of fold vibration
Analyzable variables • As with hand writing analysis, analyzable variables can be found in the voice: • F0 mean: Fundamental frequency • Pitch range: Difference between highest and lowest pitch in an utterance • Pitch variability dispersion of Pitch (e.g. standard deviation) • Pitch perturbation or jitter • Slight variations in the duration of glottal cycles • Pitch contour: Fundamental frequency values plotted over time (intonation) • F1 mean: Frequency of first (lowest) formant • F2 mean: Mean frequency of the second formant • Intensity mean: Energy values for a speech sound wave averaged over an utterance • Intensity range: Difference between highest and lowest intensity value in an utterance • Intensity variability: Measure of dispersion of the intensity values (e.g. standard deviation) • High frequency energy: Relative proportion of energy in the upper region • Speech rate: Length of an utterance • Spectral noise: A-periodic energy components in the spectrum • Zero Crossings: Number of times a sound wave graph crosses the zero line [Scherer '89]
Summary of the Psycho-physiology Psycho-Physiology: Brain how it manifests Body PERIPHERAL NERVOUS SYSTEM (Body Control Centre) AUTONOMOUS NERVOUS SYSTEM: No control over 85-90% of our brain activity • WHEN A THREAT IS ENCOUNTERED: • Move (jump) from Para-sympathetic to Sympathetic • 70% of blood directed to major muscles, brain, lungs • need for more oxygen • Some glands get an increase in activity, others less: sweat glands, saliva gland • Brain gets more oxygen for faster thinking Para-sympathetic: Homeostasis Normal state Sympathetic: THREAT: Fight or flight mode WHEN WE LIE = REACTION TO THREAT
LVA 6.50Investigation Focus Tool • A professional truth verification system which analyzes a subject’s voice, using Nemesysco’s Layered Voice Analysis technology • Allows the investigator to concentrate on the relevant issues while conducting an investigation by reviewing the subject’s emotional response to specific questions or topics • Designed for professional investigators : governments security organizations, law -enforcement agencies, corporate security officers, private investigators, etc.
LVA 6.50Investigation Focus Tool • The LVA 6.50 system has two main operation modes: • Online Mode: real time analysis of face-to-face or over-the-phone conversations . • Offline Mode: in-depth analysis of pre-recorded material.
Core parameters • Partial list: • General Stress • Emotional Stress • Cognitive Stress • Thinking effort • Hesitation
LVA 6.50Investigation Focus Tool • SPT – A numerical value describing the relatively high frequency range. The LVA associates this value with the EMO (Emotional Stress Level). • SPJ – A numerical value describing the relatively low frequency range. The LVA associates this value with the COG (Cognitive Stress Level). • JQ - A numerical value describing the distribution uniformity of the relatively low frequency range. LVA associates this value with the Global Stress Level. • AVJ – A numerical value describing the average range of the relatively low frequencies. LVA associates this with the Thinking Level. • SOS – Say or Stop. It is a numerical value describing the changes in the SPT and SPJ within a single sample. The LVA associates this value with fear and with issues the subject does not want to discuss.
ONLINE MODE Real-time analysis of conversations
Online Mode • Provides analysis during open conversation and in situations not limited to the confinements of interrogation room. • Highlights problematic issues in the conversation with real-time textual messaging ("Truth", "False Statement", etc.) as well as a graphs view. • Allows the investigator to identify the relevant issues in real-time and focus on those with further questions while discarding the irrelevant issues, saving precious investigation time, resources and energy.
Online Mode - Microphone • Real-time analysis during a face-to-face interview using a Microphone • Ordinary, visible microphone • High-gain, concealed microphone • Online mode allows the investigator to record the conversation for a thorough analysis at later time.
Online Mode - Telephone • Allows real-time analysis during a phone conversation • No special equipment required, just a phone adapter • Conversation can be recorded for a thorough analysis at later time
Online Mode - process • Creating the subject’s voice baseline: • calibrating for 10-14 seconds (as the subject initially speaks). • Conducting the interview: • The system analyzes every 1-2 seconds of the subject’s voice • Visual feedbacks to the investigator: • indications include simple textual feedbacks such as "Truth", "False Statement", "Inaccuracy“, “Subject Not Sure”, "High Stress“, etc.
Online Mode - demo • [Click on the image for demonstration]
OFFLINE MODE In-depth analysis of pre-recorded material
Offline Mode • Thorough analysis of recorded files; either imported or previously recorded with Online investigation. • Higher accuracy in analysis • Uses more parameters for increased accuracy of results. • Allows manual removal of noise and improvement of the sound quality • Provides textual and graphic feedbacks • Manages previous recordings/ investigations in a simple database
Offline Mode - demo • [Click on the image for demonstration]
LVA 6.50 - Advantages • Accurate and difficult to manipulate • Allows the investigator to focus on relevant directions and reduces investigation effort and resources. • Supports Face-To-Face interviews, interviews over the phone or analysis of recorded material • Does not require the suspect to be hooked up to a machine.
LVA 6.50 - Advantages • The suspect does not have to know that his/her voice is been analyzed for emotion detection therefore allowing a flexible interrogation. • Language independent; detecting emotions in the voice, not the actual words spoken. • User friendly interface