Detecting Deception with Detecting Deception with LIWCLIWC Aberdeen, MDAberdeen, MD

April 12, 2006April 12, 2006

Experimenters/Collaborators Jennifer Batka Emily Beadles Amanda Brown Anna Bueno Emily DeSorrento Catherine Field Adrian Gohl Michael Heller

T. Oliver Rebecca Pazoureck Linda Pierce Angela Price Rachael Ross Julie Santiago Juliana Stewart Stacie Yoho

Detecting DeceptionDetecting Deception Reviews of psychological literature on the detection

of deception tend to find accuracy rates of between 45% and 60% (cf., DePaulo & Friedman, 1998).

DePaulo et. al (1999) & Ekman et. al (1991) found that those who are highly accurate at detecting deception use various strategies that include both verbal and nonverbal cues of deception.

Newman et al. (2003) found that linguistic analysis may be used to detect deception when discussing emotional topics, like abortion.

LIWCLIWC

The LIWC is a computerized text analysis.

LIWC analyzes text word-by-word and

categorizes it into 74 different linguistic dimensions, like pronoun, present/past tense, or negations.

LIWCLIWC continued… continued… More detailed examples:Time Cognitive Process Insight Certainty

hour cause think always day know consider never

Space Discrepancy Inclusive Causation

around should with becauseup could include effect

Prior ResearchPrior Research Newman et al. hypothesized (and found) that

people use different words when lying than telling

the truth Liars try to distance themselves from the lie

Fewer first person singular pronouns (I, me, my)

Liars use less complex language Fewer exclusive words (but, except, without)

More motion words (down, up)

Liars are more negative and anxious and this “leaks” into

their language More negative emotional words

In a series of studies, we have compared the linguistic style of truthful and deceptive communications from Cameron University students. The studies vary in communication medium and topic; most studies include an additional variable. The studies can be divided into 12 data sets:

Research at Research at CameronCameron

Key DifferencesKey DifferencesTopic Medium Add.

Variable

Music Talk, Write, Type

Importance

Television Write, Type Importance

Movies Write, Type Importance

Movies-new prompt

Write None

Health Write, Type Stress

Physical Fitness

Write, Type Activity Level

General PromptGeneral Prompt

We would like you to deliver two communications. In one of the communications, we would like you to lie; in the other we want you to tell the truth.

Please write about your preferences for movies. For example, you should identify your three most

favorite movies and your three least favorite movies. Mention both old and new movies that you especially like or dislike.

Feel free to name actors that you feel strongly about. Include the type of movies you especially like and dislike.

Be sure to make your communication persuasive. Try to make your listener believe that you are telling

the truth (even if you are not). You can type as little or as much as you want.

Participants complete a questionnaire to determine the importance of the topic in their lives.

A median-split is used to identify whether or not the topic is important to each participant.

Other questions assess their feelings as they delivered the two communications.

QuestionnaireQuestionnaire

Questionnaire Results T-tests are performed to compare

responses to the questionnaire items with the scale’s midpoint

Participants report the following when they write truthful vs. deceptive statements: Feel more comfortable Believe they type more quickly Indicate they have more fun while writing Feel less negative Feel less anxious Believe they type more words

Linguistic AnalysisLinguistic Analysis Typed communications are copied into a text file

Text files are submitted to the Linguistic Inquiry Word Count (LIWC)

ANOVAs are performed with independent variables Importance of Topic: high or low (between) Topic: movies or TV (between) Communication Medium: write or type

(between) Communication Type: lie or truth (within)

Dependent Variables: Use of linguistic categories

ResultsResults

Main effects are often found for all independent variables and several interactions are often found. For example…

Causation Words: Causation Words: Importance X Lie or Truth Importance X Lie or Truth CommunicationCommunication

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

High Low

TrueLie

ImportanceImportance

Inclusive Words:Inclusive Words: Topic X Lie or Truth Topic X Lie or Truth CommunicationCommunication

5.8

6

6.2

6.4

6.6

6.8

7

7.2

7.4

Movies TV

TrueLie

TopicTopic

Optimistic Words:Optimistic Words: 3-Way Interaction3-Way Interaction

00.10.20.30.40.50.60.70.80.9

1

Movies TV

TrueLie

Topic is of High Topic is of High ImportanceImportance

00.10.20.30.40.50.60.70.80.9

1

Movies TV

TrueLie

Topic is of Low Topic is of Low ImportanceImportance

Individual t-testsIndividual t-tests Dependent t-tests to compare deceptive and

truthful communications were performed separately for the 12 data sets.

Only four linguistic categories had similar results in more than one study.

Distance Self from Distance Self from LieLie Newman et al. found people used fewer first

person singular pronouns when lying than telling the truth. We found this in the Movies-Type data set and the opposite finding in the Health-Write data set.

Other pronouns: Liars used more first person pronouns in Health-

Write Liars used fewer pronouns referring to self in the

Movies-Type data set Liars used fewer second person pronouns in the

Movies-Type data set

Language Language ComplexityComplexity Newman et al. found people used less complex

language when lying than telling the truth Liars more than truth-tellers used:

Negate words in Health-Type, Fitness-Write, and Movies-Write

Certainty words in Health-Type and Music-Type Numbers for Health-Write but liars used FEWER numbers

than truth-tellers in Movies-Write Liars were less likely than truth-tellers to use:

Discrepancy words in Fitness-Write Inclusive words in Movies-Type Words with six or more letters in TV-Write

But, liars used more exclusive words in Music-Type and more insight words than truth tellers in TV-Write

Expressions of Expressions of EmotionEmotion Newman et al. found people were more negative and

anxious when lying than telling the truth Liars more than truth-tellers used

Anger words in Movies-Write Negative emotion words in Music-Write Anxiety words in Health-Type under normal stress levels but

liars used fewer anxiety words in TV-Type Liars were less likely than truth-tellers to use

Positive feeling words in Movies-Write-New Prompt, Movies-Write, Music-Talk

Positive emotion words in Movies-Type and Music-Talk Liars used fewer affect words in Music-Talk and more

emotion words in Health-Write under moderate stress

Other FindingsOther Findings Liars used the past tense less often than

truth-tellers for Fitness-Type and Health-Write under moderate and major stress, but used it more for Health-Write normal stress

Liars were less likely than truth-tellers to use the following words: Cognitive Mechanism words in Fitness-Write Inhibition words in Movies-Write-New Prompt Communication words in Music-Write Achieve words in Music-Write

Liars used fewer words than truth-tellers in Music-Type

LimitationsLimitations Convenience sample

No rewards for telling truth or punishment for getting caught lying

Participants may see lying as helping the experimenter

The prompts may include demand characteristics

Questions?Questions?