Chapter 4: Deception Flashcards
polygraph
a device for recording an individual’s autonomic nervous system responses, including sweating, breathing, and changes in heart rate
assumption of the polygraph
deception is associated with physiological change
creation of the polygraph
- 1917: William Marston (creator of Wonder Woman) attempted to use a systolic blood pressure test as evidence of a person’s innocence
- Marston’s testimony was rejected by the court in Frye v. United States (1923) because the test had not gained acceptance by the scientific community
3 outcomes of a polygraph test
truthful, deceptive, inconclusive
applications of the polygraph test
- To help police with criminal investigations
- Polygraph disclosure tests
- Periodic testing of employees
polygraph disclosure tests
polygraph tests that are used to uncover information about an offender’s past behaviour
periodic polygraph testing of employees
- Only allowed in private companies for special investigations of wrongdoing
- Some governmental agencies in the U.S. and Canada still use the polygraph as a general screening tool
2 main types of polygraph tests
The Comparison Question Test (CQT) & The Concealed Information Test (CIT)
The Comparison Question Test (CQT)
a type of polygraph test that includes neutral questions that are unrelated to the crime, relevant questions concerning the crime being investigated, and comparison questions concerning the person’s honesty and history before the event being investigated
what is the most commonly used polygraph test in criminal investigations?
the CQT
assumption of the CQT
Examiners assume they can detect deception by comparing reactions to the relevant and comparison questions
interpreting results of the CQT
- Guilty suspects react more to relevant questions
- Innocent suspects react more to comparison questions
steps involved in doing a polygraph with a suspect of a crime
- gather information
- pre-interview
- attaches sensor and conducts acquaintance test
- testing phase
- scoring phase
- post-test interview
The Concealed Information Test (CIT)
- A type of polygraph test designed to determine if the person knows details about a crime
- Involves a series of questions in multiple-choice format, where each question has one correct answer
original name for the CIT
the guilty knowledge test
development of the CIT
Developed by Lykken in 1960
interpreting results of the CIT
- A guilty suspect is assumed to display a larger physiological response to the correct option
- An innocent suspect is assumed to display an equal physiological response to all options
assumption of the CIT
people will react more strongly to information they recognize as distinctive or important
what response is most commonly measured with the CIT?
palmar sweating
use of the CIT in North America
it is not routinely used in North America
Two reasons for the lack of widespread acceptance of the CIT
- Since polygraph examiners believe in the accuracy of the CQT, they are not motivated to use the more difficult-to-construct CIT
- For law enforcement to use the CIT, salient features of the crime must be known to the perpetrator
how is the accuracy of polygraph tests determined?
accuracy is ideally determined by presenting information known to be true or false to individuals and measuring their corresponding physiological results
two types of polygraph validity studies
laboratory & field studies
ground truth
the knowledge of whether the person is innocent or guilty
laboratory studies
involve simulating criminal behaviour by committing a mock crime
advantages of laboratory studies
the experimenter knows the ground truth and can compare the relative merits of different types of polygraph tests
disadvantage of laboratory studies
limited generalizability
field studies
involve real-life situations and actual criminal suspects with polygraph examinations
advantage of field studies
high external validity