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Suspects , Lies and Videotape: An Analysis of Authentic High-Stake Liars

Mann, Vrij & Bull. Suspects , Lies and Videotape: An Analysis of Authentic High-Stake Liars. When people are lying … What behaviours do you expect them to have ?. Background and context. Most people think that , when lying , people : Avoid eye contact

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Suspects , Lies and Videotape: An Analysis of Authentic High-Stake Liars

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  1. Mann, Vrij & Bull Suspects, Lies and Videotape: AnAnalysis of AuthenticHigh-StakeLiars

  2. Whenpeople are lying… Whatbehaviours do youexpectthemtohave?

  3. Background and context • Mostpeoplethinkthat, whenlying, people: • Avoideyecontact • Increasefidgetingnervousmovements • Nervousmovements • Previousresearch mostpeopledecrease in non functionalmovements and becomeunnaturallystill. • Thereis no relationshipbetweeneyecontact and deception

  4. Background and context • Untilnow labexperimentshaverequiredparticipantstotell a lie orthetruthaboutbeliefs and opinions. • Butsome of thesesettingsdifferfrom real lifesettings not generalizable

  5. Background and context Why do thesekind of experiments are notrepresentative? 1. Participantisaskedto lie - Someexperimentershaveallowedparticipantstochooseiflyingortellingthetruth butthe lie istold “forthe sake of theexperiment”.

  6. Background and context 2. Participantswillusuallybevideotaped and theyknowtheirlying/truthbehaviourwillbelateranalysedbysomeone 3. Tellinglies of negligibleconsequence unethicaltoofferpunishmentforlying. *So thereisstill a possibilitythathigh-stakeliars are more nervous and performnervousbehaviours.

  7. Background and context • So, toaddressallthesepoints, anotherstudywasdesignedtoanalysebehaviours of spontaneousliars. • Where? Policedepartment high-stakesituationswithsuspects.

  8. Background and context • Verydifficultto catch non-verbal behaviour in peoplewho lie. • Vrij & Mann (2001) analysed video tapes of murderers– lots of insightintothetopic. • Liarsmaynotdisplaynervousbehavioursbecausethey are probablyexperiencingotherprocessessimultaneously increasedcognitiveload orattemptedbehavioural control. • These, couldnegatenervousbehaviours

  9. Background and context Otherpointstobeconsidered: 1. Liars in thisstudywillprobablyhavetothinkhardtomaketheirliesconvincing orotherwise sentence

  10. Background and context *Peopleinvolved in complexcognitivetasksmakefewermovements: - Fewerillustrators: arm and handmovements are designedtosupplementspeech - Self-manipulations (scratching, etc) - Othersubtlehandmovements. *Increase in cognitive load results in: - A neglect of bodylanguage, reducingoverallmovements. - Increasedspeechdisturbances- Longer pauses beforeananswer - Eye-blinksuppression

  11. Background and context 2. Liarsoften try to control theirbehaviour in ordertogive a credibleimpressiontotheinterviewer. • “Motivationalimpairment”: (DePaulo&Kirkendol): thehigherthemotivationtosucceed in the lie, thegreaterthelikelihoodthatliarswill try to control theirbehaviour. • Thereis a strongbeliefthatliarsusuallymoveawaytheirgaze and makenervousmovements, so liarswill try tomantaineyecontact and avoidmovements. cultural stereotype of liars.

  12. Background and context Howdoesthishappen? Cultural belief Excesive control Notaware of bodylanguage Overzealous control Deliberatemovements and rigidity

  13. Background and context • Summary: no single pattern of behaviourisrelatedtodeception. • Pinocchio’sgrowingnosedoesn’texist • Wealsoneedtoconsider individual differences.

  14. METHOD: Participants • 16 policesuspects (13 males, 3 females= • 4 juveniles: 3 aged 13, 1 aged 15 • 15 caucasian (english), 1 asian • All interviews were done in english • Crimes: • Theft (9) • Arson (2) • Attempted rape (1) • Murder (4)

  15. PROCEDURE • Police detectives Kent County, UK • Recollection of videotaped interviews wheresuspecthad lied at somepoint and toldthetruth at another (serious cases) • Experimentedinvestigated files toconfirmifsubjectswerelyingortellingthetruth

  16. PROCEDURE • Suspectsdeny evidenceisshowntothem theyconfess. • Results: 16 clips of subjects • Truths and lieshadtobe of thesamenature (aboutevents, not personal detailsfor ex)

  17. PROCEDURE • Number of clips per participantvaried • Foreachparticipant, min 2 clips: 1 truth, 1 lie • Vrij & Winkel: differencesbetweenlying and truth-tellingbehaviour are independent of length of the clip

  18. Dependent variables • 2 observersindependentlycoded 8 behaviours • Recorderswhere(single) blindtotruth/lie variable and aim/hypothesis • Interraterreliability inter observer • Ideally 2 observerscodedeverything, butethically, theleastpossiblepeopletocode.

  19. Dependent variables • Behavioursobserved: • Gazeaversion (secondsparticipantlookedaway) • Blinking (frequency) • Head movements (frequency of head nods) • Self-manipulations (frequency) • Illustrators (freq of arm/handmovement) • Hand/fingermovements (frequency) • Speechdisturbances • Pauses (seconds) *Strongconsistencybetween 2 coders

  20. Dependent variable • The total length per minute of footageforeachbehaviourwascalculated. • Result: 1 truth-telling score, 1 lie-telling score foreachbehaviour, foreachparticipant.

  21. RESULTS • Lyingwasaccompaniedby a decrease in blinking and anincrease in pauses. • As expected, individual differencesdidoccurand therewas no behaviourthatallliarsexhibited • 50% showedincreased head movements and 50% a decrease. • 56% showed more gazeaversion and 44% showedlessgazeaversion

  22. RESULTS • 69% showed a decrease in hand and armmovementduringdeception • 33% showedanincrease. • Mostreliableindicator of deception: blinking and pauses: • 81% pausedlonger • 81% blinkedless

  23. DISCUSSION • Thisstudy has themostextensivewhich has examineddeceptivebehaviour in real-life, in high-stakessetting. • 2 significantdifferencesoccured: • Suspectsblinkedless and pausedlongerwhilelying.

  24. DISCUSSION • Somesupportforthecognitive load processlessblinking and longer pauses possibleindicators of cognitive load • Blinking strongestindicationthatcognitive load affects more suspects’ behaviourthannervousness

  25. DISCUSSION • Nixon effect: increase in blinking (he blinked more than 50 times/min duringresignation) • However, increasedcognitive load results in a decrease in blinking, butconclusions are speculative (no methodology)

  26. DISCUSSION • Large individual differenceswereshown probably no typicallyingbehaviourexists. • Probablythemostreliableindicator of deception change in theindividual’s normal behaviour

  27. DISCUSSION: Limitations • 1. Differentinterviewerswereusedfordifferentparticipants • 2. Sometomes more thanoneinterviewerwaspresent • 3. The total number of peoplepresent, varieddependingonthenumber of interviewers, attorney, etc. • In thisstudy, experimentersmanagedto control thisfactors.

  28. DISCUSSION • Researcherscan’tbesurethatthe clips thattheycomparedwere comparable • Theydidn’t compare high-stakeliarstopeoplewho are tryingtopleadtheirinnocencewhenfalselyaccused. • Theexperimenterscouldn’tobtainsuchfootage.

  29. DISCUSSION • Bothliars and truthtellersmightexperience similar behaviour • 16 participantsisnot a largesample • Differencebetweenthissample and thewholepopulation limitationforgeneralizability.

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