Who Can Best Catch a Liar?Who Can Best Catch a Liar?A Meta-Analysis of Individual A Meta-Analysis of Individual

Differences in Detecting DeceptionDifferences in Detecting Deception

Michael G. Aamodt & Heather MitchellRadford UniversityRadford, Virginia

Detecting Deception in Police Detecting Deception in Police PsychologyPsychology

Criminal investigationsCriminal investigations– SuspectsSuspects– AccusersAccusers– WitnessesWitnesses

Psych evaluationsPsych evaluations– Pre-employmentPre-employment– Fitness for dutyFitness for duty– Insanity pleasInsanity pleas– Competence to stand trialCompetence to stand trial– Threat assessmentThreat assessment

Employment Employment – InterviewsInterviews– Reference checkingReference checking– Internal affairsInternal affairs

Courtroom testimonyCourtroom testimonyHostage negotiationHostage negotiationConflict managementConflict managementPolitical survivalPolitical survival

Old Ways of Detecting DeceptionOld Ways of Detecting Deception

India- Trial by Sacred AssIndia- Trial by Sacred Ass

Arabs - Hot iron to tongueArabs - Hot iron to tongue

Chinese - Swallow rice flourChinese - Swallow rice flour

Hindus - Chew rice and spitHindus - Chew rice and spit

Inquisition - Chew and swallow a Inquisition - Chew and swallow a slice of bread and cheeseslice of bread and cheese

Judicial torture in EuropeJudicial torture in Europe

King SolomonKing Solomon

Source: Jack Annon

New Ways of Detecting DeceptionNew Ways of Detecting Deception

Electronic MethodsElectronic Methods– PolygraphPolygraph

– Voice stress analyzerVoice stress analyzer

Neurological MethodsNeurological Methods– Brain fingerprintingBrain fingerprinting

– Brain mappingBrain mapping

Extreme MethodsExtreme Methods– ChemicalsChemicals

– TortureTorture

CommunicationCommunication– Actual words usedActual words used

– ParalanguageParalanguage

– Body languageBody language

General Research FindingsGeneral Research Findings

People usually detect deception at slightly People usually detect deception at slightly above chance levelsabove chance levels

Subjects have a “truth bias” when Subjects have a “truth bias” when respondingresponding

Training can help, but…Training can help, but…

Having a baseline is essentialHaving a baseline is essential

Listeners are better than interrogatorsListeners are better than interrogators

Use of patterns rather than single cues is Use of patterns rather than single cues is essentialessential

Behavioral Indicators Will Only Be Behavioral Indicators Will Only Be Successful IfSuccessful If

You have a baseline of behaviorYou have a baseline of behavior

There is a consequence for getting caughtThere is a consequence for getting caught

The response is spontaneousThe response is spontaneous

The person does not believe the lie (e.g., The person does not believe the lie (e.g., Clinton, O.J.)Clinton, O.J.)

The lie involves a high degree of The lie involves a high degree of cognitive complexitycognitive complexity

Source: Jack Annon

Scientific InquiryScientific Inquiry

DeceivingDeceiving– Cues usedCues used– Individual differencesIndividual differences

Detecting DeceptionDetecting Deception– Overall accuracyOverall accuracy– Conditions affecting accuracyConditions affecting accuracy– Effect of trainingEffect of training– Cues usedCues used– Individual differences in accuracyIndividual differences in accuracy

Study of Deception is Study of Deception is International in NatureInternational in Nature

SwedenSweden– PPär Anders Granhag (Göteborg University)är Anders Granhag (Göteborg University)– Leif Strömwall (Göteborg University)Leif Strömwall (Göteborg University)– Maria Hartwig (Göteborg University)Maria Hartwig (Göteborg University)

United KingdomUnited Kingdom– Aldert Vrij (University of Portsmouth)Aldert Vrij (University of Portsmouth)– Siegfried Sporer (University of Aberdeen)Siegfried Sporer (University of Aberdeen)

United StatesUnited States– Bella DePaulo (University of Virginia)Bella DePaulo (University of Virginia)– Paul Ekman (University of California, San Francisco)Paul Ekman (University of California, San Francisco)– Charles Bond (Texas Christian University)Charles Bond (Texas Christian University)

CanadaCanada– Stephen Porter (Dalhousie University)Stephen Porter (Dalhousie University)

Countries with Studies in Countries with Studies in Our Meta-AnalysisOur Meta-Analysis

AustraliaAustralia

CanadaCanada

ChinaChina

EnglandEngland

GermanyGermany

IsraelIsrael

JordanJordan

NetherlandsNetherlands

ScotlandScotland

SwedenSweden

United StatesUnited States

Our StudyOur Study

Conduct a meta-analysis on individual Conduct a meta-analysis on individual differences in the ability to detect deceptiondifferences in the ability to detect deceptionMeta-analysis is a statistical review of the Meta-analysis is a statistical review of the literatureliteratureIndividual difference variablesIndividual difference variables– ExperienceExperience– ConfidenceConfidence– SexSex– PersonalityPersonality

The Literature ReviewThe Literature Review

Goal: Find all relevant studies from 1970-2003Goal: Find all relevant studies from 1970-2003– Others dates included when foundOthers dates included when found– Study had to report correlations or a statistical test Study had to report correlations or a statistical test

or raw data that could be converted into a or raw data that could be converted into a correlationcorrelation

MethodMethod– Computer searchesComputer searches– Bibliography leadsBibliography leads– Hand searches of key journalsHand searches of key journals

Literature Review ResultsLiterature Review Results

VolumeVolume– 76 studies76 studies

– 9,453 subjects9,453 subjects

Study DateStudy Date– 1960s (2)1960s (2)

– 1970s (8)1970s (8)

– 1980s (22)1980s (22)

– 1990s (26)1990s (26)

– 2000s (18)2000s (18)

SourceSource– Journal articles (67)Journal articles (67)

– Dissertations (7)Dissertations (7)

– Master’s theses (1)Master’s theses (1)

– Book chapters (1)Book chapters (1)

Each Meta-Analysis ContainsEach Meta-Analysis Contains

Number of studies (k)Number of studies (k)

Number of officers in the analysis (n)Number of officers in the analysis (n)

Mean validity coefficient (r)Mean validity coefficient (r)

95% confidence interval95% confidence interval

% of observed variance explained by sampling % of observed variance explained by sampling error error – If < 75% a search for moderators was conductedIf < 75% a search for moderators was conducted

Are Professionals Better than Are Professionals Better than Students?Students?

GroupGroup KK NN Accuracy %Accuracy %

CriminalsCriminals 11 5252 65.4065.40

Secret serviceSecret service 11 3434 64.1264.12

PsychologistsPsychologists 44 508508 61.5661.56

JudgesJudges 22 194194 59.0159.01

CopsCops 88 511511 55.1655.16

Federal officersFederal officers 44 341341 54.5454.54

StudentsStudents 122122 8,8768,876 54.2054.20

DetectivesDetectives 55 341341 51.1651.16

Parole officersParole officers 11 3232 40.4240.42

Problems in Comparing StudiesProblems in Comparing StudiesThe Stimuli are DifferentThe Stimuli are Different

TaskTask– RealismRealism– Consequence of getting caughtConsequence of getting caught

StimulusStimulus– LengthLength– Number of attemptsNumber of attempts– View (full body, head, voice only)View (full body, head, voice only)

Is Confidence Related to Accuracy?Is Confidence Related to Accuracy?

ConfidenceConfidence KK NN r r

95% CI95% CI

SE%SE%LL UU

TotalTotal 3131 3,0333,033 .06.06 .03.03 .10.10 86%86%

PolicePolice 1111 1,1741,174 .02.02 - .03- .03 .08.08 100%100%

StudentsStudents 1818 1,7471,747 .10.10 .05.05 .15.15 100%100%

Is confidence related to accuracy? YesSize of the relationship? SmallCan we generalize the findings? Yes

Cops (k=11)Students (k=17)Other (K=2)

Is Experience Related to Accuracy?Is Experience Related to Accuracy?

VariableVariable KK NN r r

95% CI95% CI

SE%SE%LL UU

ExperienceExperience 88 696696 - .07- .07 -.14-.14 .00.00 100%100%

Is experience related to accuracy? NoSize of the relationship? Can we generalize the findings? Yes

Cops (k=7)Students (k=1)Other (K=0)

Is Age Related to Accuracy?Is Age Related to Accuracy?

VariableVariable KK NN r r

95% CI95% CI

SE%SE%LL UU

AgeAge 88 862862 - .02- .02 - .08- .08 .05.05 100%100%

Is age related to accuracy? NoSize of the relationship? Can we generalize the findings? Yes

Cops (k=5)Students (k=2)Other (K=1)

Is Sex Related to Accuracy?Is Sex Related to Accuracy?

SexSex KK NN d d

95% CI95% CI

SE%SE%LL UU

Overall Overall 1515 1,4511,451 .06.06 - .06- .06 .19.19 17%17%

Law EnforcementLaw Enforcement 33 144144 .63.63 .46.46 .81.81 33%33%

StudentsStudents 1212 1,3071,307 .00.00 - .09- .09 .09.09 38%38%

Is sex related to accuracy? NoSize of the relationship? Can we generalize the findings? No

Cops (k=3)Students (k=10)Other (K=2)

Note: A positive “d” indicates men were more accurate than women

Is Personality Related to Accuracy?Is Personality Related to Accuracy?

Too few studies to determineToo few studies to determine– Openness (k=1)Openness (k=1)– Conscientiousness (k=1)Conscientiousness (k=1)– Extraversion (k=4 related, 2 on extraversion)Extraversion (k=4 related, 2 on extraversion)– Agreeableness (k=2)Agreeableness (k=2)– Neuroticism (k=2)Neuroticism (k=2)– Other (k=7)Other (k=7)

Analyses Still to be ConductedAnalyses Still to be ConductedTrack down a few missing studiesTrack down a few missing studiesInvestigate moderators for Accuracy RatesInvestigate moderators for Accuracy Rates– Medium (audio, visual, written)Medium (audio, visual, written)– Visual cue (face, body, legs)Visual cue (face, body, legs)– Presence of a baselinePresence of a baseline– Number of segments viewedNumber of segments viewed

Enhance database for sex differencesEnhance database for sex differences– Contact recent authors for more infoContact recent authors for more info

Explore truth vs. lie accuracyExplore truth vs. lie accuracy– Actual differenceActual difference– Role of truth bias and/or contextRole of truth bias and/or context

Questions?Questions?Michael G. Aamodt, Ph.D.Department of Psychology

Radford UniversityRadford, VA 24142-6946

(540) 831-5513maamodt@radford.edu

www.radford.edu/~maamodt

Citation Information Citation Information for this Presentationfor this Presentation

Aamodt, M. G., & Mitchell, H.. (2004, October). Who can best catch a liar? A meta-analysis of individual differences in detecting deception. Paper presented at the annual Meeting of the Society for Police and Criminal Psychology, Rome, Italy.