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Increasing Cognitive Load in Interviews to Detect Deceit (From International Developments in Investigative Interviewing, P 176-189, 2009, Tom Williamson, Becky Milne, and Stephen P. Savage, eds. - See NCJ-228326)

NCJ Number
Aldert Vrij; Ronald Fisher; Samantha Mann; Sharon Leal
Date Published
14 pages
After examining existing protocols for detecting deceit in investigative interviews, this chapter discusses the use of "cognitive load" as a means of detecting deceit in such interviews.
Three interview protocols are currently used to detect deceit. The two most widely used interview protocols are the Control Question Polygraph Test, which measures physiological responses during an interview, and the Behavior Analysis Interview, which measures verbal and nonverbal responses. These protocols are based on the assumption that liars are afraid of being detected, which causes them to have a distinctive arousal when answering key questions. According to the National Research Council, however, this underlying assumption is theoretically weak, since liars do not necessarily show more arousal or a distinctive arousal when answering key questions. Another approach to detecting deception is based upon the premise that people orient toward personally significant stimuli; for example, they may be interested in a conversation only when their names are mentioned. This theory is exemplified by the Guilty Knowledge Polygraph Test. Measuring orienting responses, however, requires analyzing physiological responses that often can be assessed only with impractically sophisticated and expensive equipment. Given the theoretical weakness of the fear-based approach and the practical difficulties of the orienting approach, the authors of this chapter developed another approach for discriminating between liars and truth-tellers. This approach is based on the premise that in most interviews, lying is cognitively demanding. Due to this cognitive load associated with lying, liars will be particularly debilitated when they are required to engage in cognitively demanding tasks. The cognitive overload created will create measured signs of cognitive load, such as increased stuttering, longer pauses, inconsistent answers, reduced blinking, and decreased movements. Using interview tasks that are cognitively demanding should improve discrimination between liars and truth-tellers in an information-gathering style of interview. 3 notes and 54 references