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Detecting Deception with LIWC

April 12, 2006. Detecting Deception with LIWC. Aberdeen, MD. 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

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Detecting Deception with LIWC

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  1. April 12, 2006 Detecting Deception with LIWC Aberdeen, MD

  2. 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 Experimenters/Collaborators

  3. Detecting 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.

  4. LIWC • 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.

  5. LIWC continued… • More detailed examples: TimeCognitive ProcessInsightCertainty hour cause think always day know consider never SpaceDiscrepancyInclusiveCausation around should with because up could include effect

  6. Prior 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

  7. Research at Cameron 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:

  8. Key Differences

  9. General 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.

  10. Questionnaire • 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.

  11. 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

  12. Linguistic 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

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

  14. Causation Words: Importance X Lie or Truth Communication Importance

  15. Inclusive Words:Topic X Lie or Truth Communication Topic

  16. Optimistic Words:3-Way Interaction Topic is of High Importance Topic is of Low Importance

  17. Individual 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.

  18. Distance Self from Lie • 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

  19. Language Complexity • 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

  20. Expressions of Emotion • 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

  21. Other 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

  22. Limitations • 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

  23. Questions?

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