Presentation on theme: "Professor Glenn Wilson, Gresham College, London LIE DETECTION."— Presentation transcript:
Professor Glenn Wilson, Gresham College, London LIE DETECTION
LIES BIG AND SMALL Chamberlain: “I came away with the impression that here was a man (Hitler) who could be relied upon when he had given his word”. A failure of lie detection with dire consequences. On average, people admit to lying two or three times a day. Most not sinister - just white lies, designed to spare feelings of others (an essential part of social etiquette). High stakes lying regarding guilt in relation to murder or terrorism follows different rules.
FLOATING WITCHES Mediaeval witches who denied their witchcraft were tested by dunking them in water. If they “floated” (could swim) they were found guilty and put to death. If innocent, they sank and drowned. Waterboarding suspected terrorists is reminiscent of this technique.
THE POLYGRAPH Best-known lie detector uses autonomic (unconscious) indicators of stress such as skin conductance, heart rate, respiration, blood pressure and finger temperature. Skill is in choosing questions. Must include controls (where the correct answers are known) as a baseline for comparison. Guilty knowledge paradigm most valid (items only a guilty suspect should react to). Results unreliable and not acceptable in court.
IN VINO VERITAS? Hypnotics and psychedelics tried as possible truth serums. In fact, they just make people more suggestible & obliging, so they tell you what you want to hear (c.f., hypnosis and torture). Yield more fantasy than truth, hence not useful (apart from being unethical and illegal). Suggested that oxytocin may increase trust, thus boosting “good cop” bonding effect (Brown, 2006).
SPOTTING LIARS Untrained observers about 53% accurate in detecting lying through body language (marginally better than chance). Most experts are little better (with a few exceptions). Training can diminish accuracy by inducing overconfidence (Bond & DePaulo, 2008). Accomplished liars are better at detecting lies (“it takes one to know one”). (Wright et al, 2012)
GOOD LIARS M ore variation in lying skill than in ability to detect lies. Effective liars are high in Machiavellianism and self- monitoring and usually good actors. May succeed because they lack emotions like guilt or come to “believe” their own lie. Psychopaths twice as likely to be granted parole as non- psychopaths following an interview, despite being more dangerous after release (Porter & ten Brinke, 2010).
TRUSTWORTHY FACES Faces with soft, feminine features such as a smooth, warm complexion, large mouth and rounded jawline (baby-faced) are judged more trustworthy. Those with macho traits like bushy, knitted brows, facial stubble, wide nose, small mouth (and angry look) are seen as less trustworthy. Can affect jury decisions and court sentences unfairly but stereotypes not totally without foundation (Sirrat, 2010). Gordon Brown (a), digitally altered to be more (b) and less (c) trustworthy. (Chris Solomon, Univ. Kent).
Gestures that reinforce what is being said suggest emotional involvement, hence sincerity. If a gesture does not match what is being it suggests deception. Dominant hand used more in connection with +ve emotions; non- dominant for -ve ones. Deception goes with a decrease in illustrators compared with individual’s norm (over-control of body language) but may not apply when stakes are very high (Porter & ten Brinke, 2010). ILLUSTRATORS
MICRO-EXPRESSIONS Fleeting expressions, often detectible only by slow- motion video, may betray emotions that individual is trying to hide. Absence of appropriate emotion (e.g., grief) is equally telling. System of reading facial expressions of emotion developed by Paul Ekman widely applied (basis for “Dr Cal Lightman” in Lie to Me). Criticised as lacking empirical validation (e.g., occurrence of false positives).
EMOTIONAL LEAKAGE Face sometimes betrays true emotions when inappropriate feelings break through a social façade (Porter & ten Brinke, 2008). Micro-expressions of disgust and anger displayed by Kato Kaelin as he “charmed” the prosecutor in testimony for O.J. Simpson (Ekman, 2003). Asked to curtail smiling and brow movements during true and false accounts, liars are less able to do so (Hurley & Frank, 2011). Kim Philby (“the third man”) was unable to contain a smirk while denying he was a Russian spy. Tracie Andrews stabbed fiance to death, then fabricated a story about a road rage attack. Her TV appeal featured distress and grief but occasional flashes of anger intruded, giving clues as to her capability.
SMILES FAKED VS FELT Contrived expressions differ from those that are spontaneous. Felt smiles include wrinkling around the eyes and cheeks. Faked smiles more restricted to mouth, show lower teeth, often asymmetrical and contain elements of negative emotions such as anger or disgust. Felt smiles generate more empathy and trust in others. Skilled actors can smile convincingly by conjuring happy feelings.
EYE MOVEMENTS Popular belief that liars avert their eyes not reliable because people can over-ride this tendency. NLP claim that looking up/left indicates genuine memory recall, whereas up/right is accessing creative brain (“making it up”) is not supported by evidence (Wiseman et al, 2012). Computerised eye tracking more promising - compares patterns to critical (searching) questions against individual’s own neutral baseline. Reported as 82% accurate (Bhaskaran, 2011).
STRESS SIGNS Signs of emotional arousal - blinking, blushing, sweating, dry mouth (drinking water) may indicate lying. But many other reasons for feeling stressed during public speaking or during interrogation, so not sufficient indictment in themselves. Same true for self-comforting gestures such as folding arms and touching the face. Blink rate actually often lower in liars (another example of over-control). An absence of appropriate distress (esp. in the upper face) may be equally telling.
LIP PRESSING Lip swallowing (sucking the lips inwards) usually accompanies thinking and uncertainty about something (especially when the outcome might be bad). Lip compression is associated with lying (DePaulo & Morris, 2004). May represent desire to control the urge to blurt out something that one would prefer the world not to know (“buttoning the lip”).
THE PINOCCHIO EFFECT Touching the nose - classic sign of discomfort and self- consciousness. According to Hirsch & Wolf (2001) this is because the nose contains erectile tissue causing it to become engorged with stress. When Clinton was denying sex with Monica Lewinsky he was observed to touch his nose particularly at moments of untruthfulness.
VOICE STRESS ANALYSIS Various computer & phone applications claim to detect lying through micro- tremors in the voice and higher pitch. Scientific studies (e.g. comparing VSA of drug users denying use of drugs against urine analysis) shows them to be little better than chance. At best, detects stress, not lying specifically, but like the polygraph, may be useful in prompting confessions.
THERMAL IMAGING Infrared cameras are being tested as lie detection tools at airports (already used for fever detection). Asked to lie about their travel plans, skin temp. around people’s eyes rose significantly (no change for truth tellers). 64% of truth-tellers & 69% of liars correctly classified. However, interviewers’ judgements were more accurate (72% & 77%). Thermal imaging added nothing significant to this (Warmelink, 2011).
LIES IN THE BRAIN Brain activity (fMRI) may capture a lie “at its source”. Theory is that telling the truth just involves memory but lying requires (a) suppression of the truth, (b) invention of a new scenario. Lying should thus engage more frontal (and perhaps parietal) areas. Claims of 90% accuracy have been made for this approach but premature to use as evidence in court (Langleben & Moriarty (2012). Not immune to cheating by self-stimulation in control condition (Ganis et al, 2011).
PUNE POISONING In a Mumbai courtroom (2008) Aditi Sharma and her lover Paveen were convicted of conspiracy to kill her fiancé by putting arsenic in his McDonalds meal. With her consent, her EEG responses (P300) to critical vs neutral statements in a “guilty knowledge” paradigm were recorded. The judge agreed they showed “experiential knowledge” of the details of the crime, corroborating other evidence. Both sentenced to life in prison.
SPEECH PATTERNS Speech patterns change when people are lying. Increase in repetitions, undue emphasis and hesitations (“ums” and “ers”). Liars tend to start their answers later (unless well prepared, in which case it may be sooner). Pace is slower, giving them more time to construct a story. They talk less, giving fewer facts/details that might be checked, particularly those close to the crime. Usually come across as negative and uncooperative.
LINGUISTICS Choice of words and phrases betray guilt better than non-verbals (Vrij, et al, 2011). Guilty people use oblique, more than direct denials (“I’m trying to tell you the truth”) and tentative words like “maybe”, “guess”, “perhaps” (avoiding commitment). Simpson (on the run): “I’m the only one who deserves to die” (confession). Clinton: “I did not (expanded contraction) have sexual relations (vague) with that woman” (distancing). Referring to a missing person in the past tense (“my wife was amazing”) may suggest murder.. Michael Jackson insisted he “would never harm a child” (avoiding words like molest).
COUNTING WORD CATEGORIES Pennebaker et al (2007): software for analysing texts that suggest lying by frequency of word categories. Liars use: (1) less self-referencing (I, me) - avoiding ownership and responsibility for their behaviour. (2) more negative emotion, (hate, worthless, sad) – implying self-loathing. (3) fewer exclusions (except, but, nor) – words distinguishing what they did and did not do. Yields 67% accuracy as against 52% for human judges. Similar findings for linguistic analysis of deceptive online dating profiles (Toma & Hancock, 2012).
ELEMENTS OF TRUTHFUL TALES Criteria -Based Content Analysis assesses reality of a narrative. The more criteria satisfied the more likely the story is to be true. Include: amount of detail, unusual and superfluous details, embedding within context of time and place, verbatim conversation, subjective feelings, self-deprecation, admission of memory lapses and spontaneous corrections. Porter & ten Brinke (2010): separate validation is needed for CBCA criteria and a quantitative weighting formula. System susceptible to coaching?
INTERVIEWING TECHNIQUES Skilled questioning can increase cognitive load and wrong-foot suspects (Vrij et al, 2011). Requiring suspects to recall events in reverse order increases truth/lie differences. Unexpected questions useful when suspect has well-prepared story. Having suspect sketch locations and positions of people in their account provides material that can be checked. Strategic use of evidence increases pressure (e.g., withholding known facts until later in interview, when they might already have been contradicted). Coercive methods are unethical, illegal & ineffective.
SUMMARY Many well-known methods of lie detection lack reliability – including polygraph, truth drugs, voice stress & thermal imaging. May help prompt confession or raise confidence in person’s innocence. Body language indicators also vexed. Popular beliefs about how liars give themselves away are often wrong. Publicity given to research findings can negate their usefulness because liars learn to over-ride them. Motivated liars often avoid showing agitation, minimise arm gestures and eye- blinks and stare the interviewer straight in the eye. Departures from baseline (in either direction) are more valid indicators. Adrian Prout confessed to killing his wife (missing 4yrs) after failing a polygraph test in 2011. Verified by him guiding police to her remains.
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