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?
Maria: December 19th.
Frank: Uh… the 19th…
Maria: My two friends from school
are coming, and Robin…
Frank: I’d love to!
• 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.
Frank: Oh gee, I’m having an
appendectomy that night.
• Concealment
• Falsification
• Misdirecting
• Telling the truth falsely
• Half-concealment
• Incorrect inference dodge.
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?