Investigative Interviews and Deception Detection
The ability to detect deception is a major component of police interviewing. Given that the Reid Model of Interrogation is premised on a presumption of guilt, the ability of an investigator to detect deception is crucial. Applied social psychologist Aldert Vrij (2008) has defined deception as “a successful or unsuccessful deliberate attempt, without forewarning, to create in another a belief which the communicator considers to be untrue” (p. 15).
Historically, deception among potential suspects was tested using various forms of ordeals. For example, the use of rice, or the ordeal of rice chewing, was used in different cultures in the past to identify liars. In ancient China and India, suspects were forced to chew and then spit out rice. If any rice remained stuck to their tongue they were assumed to be guilty. This method of deception detection was based on the premise that individuals who were lying would be nervous and, as a result, would be unable to generate saliva (Porter & Wrightsman, 2013). Our current polygraph technique is based on a very similar, albeit more sophisticated, premise. A typical polygraph procedure measures changes in autonomic nervous system functioning. Briefly, the autonomic nervous system (ANS) is responsible for regulating automatic or involuntary functions such as heart rate, blood pressure, breathing, and skin conductance. The polygraph is based on an assumption that our levels of emotional arousal – increases in heart rate, blood pressure, skin conductance activity – are likely to be elevated when we are lying.
Photo of the Autonomic Nervous System (ANS)
Source: Wikimedia Commons
Most theories of deception and deceptive behaviour are similarly based on the premise that lying is correlated with elevated levels of arousal. From this theoretical perspective, when an individual is engaged in lying or deceptive behaviour they are more cognitively engaged; that is, the liar is making a concerted effort to create a false narrative that is plausible to their audience. As a result, many theories of deception posit that liars will unintentionally let some indicators of deception “slip” that can be detected by observers (Porter & Wrightsman, 2013). Unfortunately, lie detection efforts have often relied on stereotypes or myths about lying and expected behaviours. Investigators often assume that there is a “Pinocchio’s nose” particularly focusing on non-verbal cues such as gaze aversion, posture or fidgeting, and nervousness as indicators of deception. However, a large body of empirical research offers little support for the utility of these indicators (Vrij, 2008). To date, forensic psychologists have carried out a large body of research exploring the ability of criminal justice personnel to detect deception in others. Most of this research suggests that, on average, the majority of law enforcement and criminal justice personnel are not particularly good at correctly identifying a liar (see Vrij, Granha, & Porter, 2011).
Forensic psychologist Stephen Porter has conducted extensive research on deception detection and improving the ability of law enforcement personnel to detect deception. For example, in one study, Porter and his colleagues (2000) offered parole officers a training workshop designed to improve deception detection. Prior to the workshop, the researchers measured the participants’ ability to accurately classify liars – their performance was below average. However, following the workshop, parole officers’ exhibited significant levels of improvement. In general, research shows that there are some non-verbal cues that can serve as viable indicators of deception. Nevertheless the ability to accurately recognize and assess these cues requires training. Porter and Wrightsman (2013) have provided a detailed summary of potential non-verbal indicators of deception. The table bellows selects and offers a brief summary of two of these non-verbal cues:
Non-Verbal Indicators of Deception
Indicator Description
Emotional Facial Expression
There is some empirical research that suggests that liars will often attempt to manipulate their facial expressions to appear consistent with their fabricated narratives. Psychologist Paul Ekman has argued that we can detect deception by monitoring microexpressions – brief leaks in genuine emotions that manifest in the form of half- or full-face emotional expressions for a fraction of a second (p. 121).
Research suggests that microexpressions are easier to spot when the liar is trying to hide high-intensity emotions as compared to low-intensity emotions. However, microexpressions are not exclusive to deceptive emotions and sometimes surface in genuine expressions.
Blink Rate
The use of the rate of blinking as an indicator of deception is controversial. There is some empirical support showing that liars on average blink more than people telling the truth, but the average differences are statistically small. Moreover it is believed that blink rate changes under a very specific set of circumstances. That is, liars may be more likely to blink when they are trying to conceal their emotional responses specifically to questions pertaining directly to the crime.
Source: Porter and Wrightsman (2013)
Interviewing Witnesses: Common Errors in Interviewing
In addition to interviewing suspects and victims of crime, police must interview potential eyewitnesses to generate information as part of the criminal investigation process. A large area of research in forensic psychology has focused on interviewing witnesses and information generation. In the 1980s, two large studies were conducted in the United States and Britain that focused on typical police interviewing procedures and their overall effectiveness (Fisher, Geiselman, & Raymond, 1987; George & Clifford, 1992). Findings from both studies suggested that police interviewing styles were generally ineffective at generating information and were plagued by consistent problems. For example, American and British police officers typically started their interviews with general open-ended questions (e.g., “Tell me what happened”) but then quickly interrupted witnesses with direct, short-answer questions and leading questions, dominating interviews and rendering witnesses to a passive role. Fisher and his colleagues have outlined several types of common errors in police interviews, which are outlined below (Fisher, Geiselman, & Raymond, 1987, Fisher et al, 2001):
Source: Fisher, Geiselman, & Raymond (1987)
A major potential source of the problems identified above is the lack of training or instruction on interview procedures with cooperative witnesses (Fisher, 1995; Fisher, Milne, & Bull, 2011). In general, many Canadian police officers do not receive much instruction on how to properly interview eyewitnesses (Snook, Eastwood, Stinson, Tedeschini, & House, 2010).
You are required to submit ONE Learning Debrief for each module (lesson 3 OR 4).
Interrogation In this lesson, we discussed the Reid interrogation model. Do you use minimizing and maximizing techniques when interrogating? Do you think they are effective? Are there any other techniques that you use?
Deception Detection What indicators of deception have you commonly relied upon in interviews with potential suspects? Are there “gray” areas, or ambiguous indicators, that you think are less reliable? Where do you think psychology theory and research could help improve detecting deception in law enforcement?
Interviewing Did you recognize any of the common interviewing errors when interviewing eye-witnesses? What do you think about the cognitive interview technique?