Deceptive Speech Frank Enos • April 25, 2005 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 Why study deception? Law enforcement / Jurisprudence Intelligence / Military / Security Business Politics Mental health practitioners Social situations Is it ever good to lie? 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 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 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 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! How to Lie (Ekman‘’01) 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? • Concealment Maria: December 19th. • Falsification Frank: Uh… the 19th… • Misdirecting Maria: My two friends from school • Telling the truth falsely • Half-concealment are coming, and Robin… • Incorrect inference dodge. Frank: I‘d love to! 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? • Concealment Maria: December 19th. • Falsification Frank: Uh… the 19th… • Misdirecting Maria: My two friends from school • Telling the truth falsely • Half-concealment are coming. • Incorrect inference dodge. Frank: Oh gee, I‘m having an appendectomy that night. Reasons To Lie (Frank‘’92 ) Self-preservation Self-presentation *Gain Altruistic (social) lies 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 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 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 Features of Deception Cognitive Coherence, fluency Interpersonal Discourse features: DA, turn-taking, etc. (Some addressed by Statement Analysis) Emotion 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) 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 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 Deception Experiments (Frank‘’92) Addresses lying as dependent variable. Type and form of lie Motive for Lying Concealment Self-preservation Falsification Self-presentation Misdirecting Gain Telling the truth falsely Altruistic (social) lies Half-concealment Incorrect inference dodge. 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 The Good Old Days Mehrabian 1971: Nonverbal Betrayal of Feeling 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 Modeling Deception in Speech Lexical Prosodic/Acoustic Discourse Deception in Speech (Depaulo ’03) Positive Correlates Interrupted/repeated words References to ―external‖ events Verbal/vocal uncertainty Vocal tension F0 Deception in Speech (Depaulo ’03) Negative Correlates Subject stays on topic Admitted uncertainties Verbal/vocal immediacy Admitted lack of memory Spontaneous corrections Problems, revisited Differences due to: Gender Social Status Language Culture 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 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‖ 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 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) 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 Our Future Work Individual differences Wizards of deception Mark Frank Mock Theft Paradigm New paradigm Shorter Addition of personality test Higher stakes?