Deceptive Speech

1. Deceptive Speech Frank Enos • April 25, 2005

2. Defining Deception • Deliberate choice to mislead a target without notification (Ekman‘’01) • Often to gain some advantage • Excludes: • Self-deception • Theater, etc. • Falsehoods due to ignorance/error • Pathological behaviors

3. Why study deception? • Law enforcement / Jurisprudence • Intelligence / Military / Security • Business • Politics • Mental health practitioners • Social situations • Is it ever good to lie?

4. Why study deception? • What makes speech “believable”? • Recognizing deception means recognizing intention. • How do people spot a liar? • How does this relate to other subjective phenomena in speech? E.g. emotion, charisma

5. Problems in studying deception? • Most people are terrible at detecting deception — ~50% accuracy (Ekman & O’sullivan 1991, etc.) • People use subjective judgments — emotion, etc. • Recognizing emotion is hard

6. Problems in studying deception? • Hard to get good data • Real world • Laboratory • Ethical issues • Privacy • Subject rights • Claims of success • But also ethical imperatives: • Need for reliable methods • Debunking faulty methods • False confessions

7. Frank Tells Some Lies Maria: I’m buying tickets to Handel’s Messiah for me and my friends — would you like to join us? Frank: When is it? Maria: December 19th. Frank: Uh… the 19th… Maria: My two friends from school are coming, and Robin… Frank: I’d love to!

8. How to Lie (Ekman‘’01) • Concealment • Falsification • Misdirecting • Telling the truth falsely • Half-concealment • Incorrect inference dodge.

9. • Concealment • • Falsification • • Misdirecting • • Telling the truth falsely • • Half-concealment • • Incorrect inference dodge. Frank Tells Some Lies Maria: I’m buying tickets to Handel’s Messiah for me and my friends — would you like to join us? Frank: When is it? Maria: December 19th. Frank: Uh… the 19th… Maria: My two friends from school are coming, and Robin… Frank: I’d love to!

10. • Concealment • • Falsification • • Misdirecting • • Telling the truth falsely • • Half-concealment • • Incorrect inference dodge. Frank Tells Some Lies Maria: I’m buying tickets to Handel’s Messiah for me and my friends — would you like to join us? Frank: When is it? Maria: December 19th. Frank: Uh… the 19th… Maria: My two friends from schoolare coming. Frank: Oh gee, I’m having an appendectomy that night.

11. Reasons To Lie (Frank‘’92 ) • Self-preservation • Self-presentation • *Gain • Altruistic (social) lies

12. How Not To Lie (Ekman‘’01) • Leakage • Part of the truth comes out • Liar shows inconsistent emotion • Liar says something inconsistent with the lie • Deception clues • Indications that the speaker is deceiving • Again, can be emotion • Inconsistent story

13. How Not To Lie (Ekman‘’01) • Bad lines • Lying well is hard • Fabrication means keeping story straight • Concealment means remembering what is omitted • All this creates cognitive load  harder to hide emotion • Detection apprehension (fear) • Target is hard to fool • Target is suspicious • Stakes are high • Serious rewards and/or punishments are at stake • Punishment for being caught is great

14. How Not To Lie (Ekman‘’01) • Deception guilt (vs. shame) • Stakes for the target are high • Deceit is unauthorized • Liar is not practiced at lying • Liar and target are acquainted • Target can’t be faulted as mean or gullible • Deception is unexpected by target • Duping delight • Target poses particular challenge • Lie is a particular challenge • Others can appreciate liar’s performance

15. Features of Deception • Cognitive • Coherence, fluency • Interpersonal • Discourse features: DA, turn-taking, etc. • (Some addressed by Statement Analysis) • Emotion

16. Describing Emotion • Primary emotions • Acceptance, anger, anticipation, disgust, joy, fear, sadness, surprise • One approach: continuous dim. model (Cowie/Lang) • Activation – evaluation space • Add control/agency • Primary E’s differ on at least 2 dimensions of this scale (Pereira)

17. Problems With Emotion and Deception • Relevant emotions may not differ much on these scales • Othello error • People are afraid of the police • People are angry when wrongly accused • People think pizza is funny • Brokow hazard • Failure to account for individual differences

18. 20th Century Lie Detection • Polygraph • http://antipolygraph.org • The Polygraph and Lie Detection (N.A.P. 2003) • Voice Stress Analysis • Microtremors 8-12Hz • Universal Lie response • http://www.love-detector.com/ • http://news-info.wustl.edu/news/page/normal/669.html • Reid • Behavioral Analysis Interview • Interrogation

19. Type and form of lie Concealment Falsification Misdirecting Telling the truth falsely Half-concealment Incorrect inference dodge. Motive for Lying Self-preservation Self-presentation Gain Altruistic (social) lies Deception Experiments (Frank‘’92)Addresses lying as dependent variable.

20. Deception Experiments (Frank‘’92)Addresses lying as dependent variable. • Scenario • *Topic of the lie: opinion; state; event. • Stakes for lying / stakes for telling the truth. • Interval between event and subject’s account. • Interpersonal structure • Characteristics of the liar • Characteristics of the target • Presence or absence of a “coach” • Presence or absence of others

21. The Good Old Days • Mehrabian 1971:Nonverbal Betrayal of Feeling

22. Bulk of extant deception research… • Not focused on verifying 20th century techniques • Done by psychologists • Considers primarily facial and physical cues • “Speech is hard” • Little focus on automatic detection of deception

23. Modeling Deception in Speech • Lexical • Prosodic/Acoustic • Discourse

24. Deception in Speech (Depaulo ’03) • Positive Correlates • Interrupted/repeated words • References to “external” events • Verbal/vocal uncertainty • Vocal tension • F0

25. Deception in Speech (Depaulo ’03) • Negative Correlates • Subject stays on topic • Admitted uncertainties • Verbal/vocal immediacy • Admitted lack of memory • Spontaneous corrections

26. Problems, revisited • Differences due to: • Gender • Social Status • Language • Culture

27. Columbia/SRI/Colorado Corpus • With Julia Hirschberg, Stefan Benus, Sarah Friedman, Sarah Gilman, and colleagues from SRI/ICSI and U. C. Boulder • Goals • Examine feasibility of automatic deception detection using speech • Discover or verify acoustic/prosodic, lexical, and discourse correlates of deception • Model a “non-guilt” scenario • Create a “clean” corpus

28. Columbia/SRI/Colorado Corpus • Inflated-performance scenario • Motivation: financial gain and self-presentation • 32 Subjects: 16 women, 16 men • Native speakers of Standard American English • Subjects told study seeks to identify people who match profile based on “25 Top Entrepreneurs”

29. Columbia/SRI/Colorado Corpus • Subjects take test in six categories: • Interactive, music, survival, food, NYC geography, civics • Questions manipulated  • 2 too high; 2 too low; 2 match • Subjects told study also seeks people who can convince interviewer they match profile • Self-presentation + reward • Subjects undergo recorded interview in booth • Indicate veracity of factual content of each utterance using pedals

30. CSC Corpus: Data • 15.2 hrs. of interviews; 7 hrs subject speech • Lexically transcribed & automatically aligned  lexical/discourse features • Lie conditions: Big Lie / Little Lie • Segmentations (LT/LL): slash units (5709/3782), phrases (11,612/7108), turns (2230/1573) • Acoustic features (± recognizer output)

31. CSC Corpus: Results • Classification (Ripper rule induction, randomized 5-fold cv) • Slash Units / Little Lies — Baseline 39.8% err • Lexical & acoustic: 37.2 %; + subject dependent: 33.6% • Phrases / Little Lies — Baseline 38.2% err • Lexical & acoustic 34.0%; + subject dependent: 27.9% • Other findings • Positive emotion words deception (LIWC) • Pleasantness  deception (DAL) • Filled pauses  truth • Some pitch correlation — varies with subject

32. Our Future Work • Individual differences • Wizards of deception • Mark Frank Mock Theft Paradigm • New paradigm • Shorter • Addition of personality test • Higher stakes?