PSYC 3500: Deception

Course Overview

  • Title: Liar: Deception and Malingering

Today's Agenda

  • The Polygraph

    • Background, Test Types, Research

  • Brain-Based Deception Detection

  • Verbal and Nonverbal Cues to Lying

  • Malingering

The Polygraph

Background & Usage

  • Definition: A polygraph is a tool to measure physiological activity.

    • Physiological Activities Assessed:

      1. Respiration (breathing)

      2. Electrodermal activity/Skin conductance/Galvanic skin response (sweating)

      3. Heart rate/Blood pressure

  • Polygraph Exam/Test:

    • Interrogation + polygraph involves responding to specific yes/no or multiple-choice questions.

  • Common Uses:

    • Criminal investigations, security pre-employment screening, disclosure tests.

  • Admissibility: Polygraph results are NOT admissible in Canadian courts.

Polygraph Test Participation

  • Innocent Accused: Willingness to take the test can vary based on confidence in innocence.

  • Guilty Accused: Individuals may refuse due to fear of detection.

Comparison Question Test (Reid, 1977)

Phases of Testing

  • Phase I: Pretest interview and question development:

    1. Irrelevant Questions: Neutral questions.

    2. Relevant Questions: Pertaining to specific crime.

    3. Comparison Questions: Related to past misbehavior.

  • Phase II: Questions asked while attached to polygraph.

  • Phase III: Physiological responses are scored based on assumptions:

    • Guilty parties will show a greater response to relevant questions.

    • Innocent parties will show a greater response to comparison questions.

  • Phase IV: Confronting the suspect post-analysis.

CQT: Problems

  • Use of extra-polygraph cues can complicate results.

  • Innocent people may show a stronger response to comparison vs relevant questions.

  • Guilty parties may show a stronger response to relevant vs comparison questions.

Concealed Information Test (Lykken, 1981)

  • Purpose: Probes for concealed information rather than outright lying.

  • Question Format: Multiple-choice questions involving consent.

  • Assumptions: Guilty parties will respond to the correct alternative, while innocent parties will show similar responses to all presented alternatives.

CIT: Problems

  • Applicability of questions can vary.

  • Examiner expectancy may bias results.

  • The test does not confirm whether a suspect committed an offense.

Research on the Polygraph

Types of Research

  • Lab Studies:

    • Advantages: Ground truth known; control over variables; larger sample sizes for generalizability.

    • Disadvantages: May lack real-world applicability.

  • Field Studies:

    • Advantages: Conducted with real suspects; trained polygraphers.

    • Disadvantages: Ground truth is not definitively known.

Accuracy of Polygraph Tests

  • Comparison Question Test:

    • Detection Rates: 84 – 92% accurate at detecting guilty individuals; 9 – 24% of innocent individuals falsely identified as guilty.

  • Concealed Information Test:

    • Detection Rates: 76 – 85% accurate at detecting deception; approximately 95% accurate at detecting innocent individuals; 15 – 24% of guilty falsely identified as innocent.

  • High false positive and false negative rates need consideration.

Countermeasures

  • Definition: Actions taken by individuals to attempt to fool the polygraph.

    • General Countermeasures: Use of drugs or alcohol to diminish physiological responses.

    • Specific Point Countermeasures: Physical or mental practices to manipulate results.

Brain-Based Deception Detection

Techniques

  • Thermal Imaging: Utilizing facial blood flow to detect deception without sensors.

  • Event-Related Potentials (ERP): Measures brain responses to stimuli using scalp electrodes.

    • P300: Occurs in response to infrequent significant stimuli, with an accuracy of approximately 74 – 80%.

  • fMRI: Current cutting-edge approach identifying areas activated during deception (90 – 100% accuracy in controlled settings).

    • Areas of Activation: Prefrontal cortex, anterior cingulate regions.

    • Limitations: Susceptible to countermeasures; based on healthy subjects only.

Study Outcome

  • Brain Says Guilty (McCabe et al., 2011): Evaluates impact of brain imaging evidence on juror decisions.

  • Importance of presenting evidence challenging fMRI validity in court.

Verbal and Nonverbal Cues to Lying

Activity

  • One Truth and a Lie: Develop two emotional childhood stories (one true, one fabricated) and assess detection.

Potential Cues to Lying

  • Verbal Cues:

    • Increased voice pitch, speech fillers, slower speech rate, less emotional expression.

  • Nonverbal Cues:

    • Fewer movements, fake smiles, lack of engagement in content.

  • Leakage Cues: Brief, involuntary facial expressions showing concealed emotions.

Accuracy of Detection

  • Overall Accuracy Rates:

    • Professionals: 55.5%

    • Students: 54.2%

    • Accuracy varies among professional lie catchers.

  • High-Stake Situations: Better detection rates from police officers.

Malingering

Definition

  • Malingering: Intentional production of false or exaggerated symptoms for external gain.

Reflect and Discuss

  • Consider personal experiences and contexts that might lead to malingering behavior.

Models and Cues

Adaptational Model of Malingering

  1. Perceived adversarial context

  2. High personal stakes

  3. Lack of viable alternatives

Cues to Malingered Psychosis

  • Rationale motives, conflicting reports, rare symptoms, willingness to discuss symptoms, and absurd symptom reporting.

Structured Interview of Reported Symptoms (Rogers et al., 1992)

  • Components: 172 questions assessing the believability of symptoms.

    • Four possible outcomes: Honest, Indeterminate, Probable feigning, Definite feigning.

SIRS Scales

  • Description:

    • Rare Symptom Scale, Absurd Symptoms, Blatant Symptoms, Severity of Symptoms, etc.

Probable Malingering

  • Scoring indications of malingering based on multiple scales.

Case Example

  • Overview presented in Dr. Sohom Das's podcast regarding faking mental illness.

Next Steps

  • Submission Deadlines:

    • Research reflection and essay outline by Feb 14, 2025.

    • Read Chapter 5 in Forensic Psychology Textbook on Eyewitness Testimony.