Deceptive Speech

1
Deceptive Speech

• Frank Enos April 25, 2005

2
Defining Deception

• Deliberate choice to mislead a target without
  notification (Ekman01)
• Often to gain some advantage
• Excludes
• Self-deception
• Theater, etc.
• Falsehoods due to ignorance/error
• Pathological behaviors

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Why study deception?

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

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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 Osullivan 1991, etc.)
• People use subjective judgments emotion, etc.
• Recognizing emotion is hard

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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

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Frank Tells Some Lies

• Maria Im buying tickets to Handels 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 Id love to!

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How to Lie (Ekman01)

• Concealment
• Falsification
• Misdirecting
• Telling the truth falsely
• Half-concealment
• Incorrect inference dodge.

9
Frank Tells Some Lies

• Maria Im buying tickets to Handels 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 Id love to!

10
Frank Tells Some Lies

• Maria Im buying tickets to Handels 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, Im having an appendectomy
  that night.

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Reasons To Lie (Frank92 )

• Self-preservation
• Self-presentation
• Gain
• Altruistic (social) lies

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How Not To Lie (Ekman01)

• 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

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How Not To Lie (Ekman01)

• 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

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How Not To Lie (Ekman01)

• 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 cant 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 liars performance

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Features of Deception

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

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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 Es differ on at least 2 dimensions of
  this scale (Pereira)

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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

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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.ht
  ml
• Reid
• Behavioral Analysis Interview
• Interrogation

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Deception Experiments (Frank92)Addresses lying
as dependent variable.

• 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

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Deception Experiments (Frank92)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 subjects account.
• Interpersonal structure
• Characteristics of the liar
• Characteristics of the target
• Presence or absence of a coach
• Presence or absence of others

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The Good Old Days

• Mehrabian 1971 Nonverbal Betrayal of Feeling

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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

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Modeling Deception in Speech

• Lexical
• Prosodic/Acoustic
• Discourse

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Deception in Speech (Depaulo 03)

• Positive Correlates
• Interrupted/repeated words
• References to external events
• Verbal/vocal uncertainty
• Vocal tension
• F0

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Deception in Speech (Depaulo 03)

• Negative Correlates
• Subject stays on topic
• Admitted uncertainties
• Verbal/vocal immediacy
• Admitted lack of memory
• Spontaneous corrections

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Problems, revisited

• Differences due to
• Gender
• Social Status
• Language
• Culture

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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

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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

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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

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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)

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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

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Our Future Work

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