Pär Anders Granhag

Pitfalls and Opportunities in Nonverbal and Verbal Lie Detection

The question of whether discernible differences exist between liars and truth tellers has interested professional lie detectors and laypersons for centuries. In this article we discuss whether people can detect lies when observing someone’s nonverbal behavior or analyzing someone’s speech. An article about detecting lies by observing nonverbal and verbal cues is overdue. Scientific journals regularly publish overviews of research articles regarding nonverbal and verbal cues to deception, but they offer no explicit guidance about what lie detectors should do and should avoid doing to catch liars. We will present such guidance in the present article.

Outsmarting the liars The benefit of asking unanticipated questions

We hypothesised that the responses of pairs of liars would correspond less with each other than would responses of pairs of truth tellers, but only when the responses are given to unanticipated questions. Liars and truth tellers were interviewed individually about having had lunch together in a restaurant. The interviewer asked typical opening questions which we expected the liars to anticipate, followed by questions about spatial and/or temporal information which we expected suspects not to anticipate, and also a request to draw the layout of the restaurant. The results supported the hypothesis, and based on correspondence in responses to the unanticipated questions, up to 80% of liars and truth tellers could be correctly classified, particularly when assessing drawings.

Guilty and innocent suspects’ strategies during police interrogations

Abstract Deception detection has largely failed to investigate guilty and innocent suspects’ strategies. In this study, mock suspects (n=82) were interrogated by police trainees (n=82) who either were or were not trained in the technique to strategically use the evidence (the SUE technique). Analyses revealed that guilty suspects to a higher degree than innocent suspects applied strategies in order to appear truthful. Guilty suspects reported diverse strategies, while innocent suspects reported the strategy to tell the truth like it had happened, indicating a belief in the visibility of innocence. The realism in the suspects’ expectation about how their veracity was judged was largely dependent on the way in which they had been interrogated. The truth-telling suspects who were interrogated according to the SUE technique were optimistic about being judged as truthful; this optimism was warranted as the vast majority of them were classified as truthful. The SUE technique seems to help (a) spotting guilty suspects without them being aware of it and (b) spotting innocent suspects, and they become aware of it. That innocent (but not guilty) suspects can read how the interrogator views them is advantageous for the investigative process.

A new theoretical perspective on deception detection: On the psychology of instrumental mind-reading

Abstract To be able to assess the veracity of statements offered by suspects, witnesses and alleged victims is of paramount importance in legal settings. The aim of this paper is to provide an initial piece of scientific support for the idea that psychologically informed mind-reading can improve peoples ability to detect deception. To this end, a theoretical framework is sketched; a framework resting upon psychological notions from three domains: (a) the psychology of mind-reading, (b) the psychology of self-regulation, and (c) the psychology of guilt and innocence. Importantly, the term mind-reading is used in an instrumental (vs descriptive) manner, where the goal is to improve the ability to predict a persons behaviour (not to read the content of a persons mind). It is argued that the mind-reading process can be facilitated by theoretical and empirical work pertaining to ‘the psychology of guilt’ and ‘the psychology of innocence’. Using psychologically informed mind-reading, predictions of guilty and innocent suspects’ behaviour are specified, and gauged against existing empirical work. Finally, a recently published training study is used to illustrate how the outcome of instrumental mind-reading can be translated into interview tactics, and ultimately improve interviewers’ ability to detect deception.

Outsmarting the Liars: Toward a Cognitive Lie Detection Approach

Five decades of lie detection research have shown that people’s ability to detect deception by observing behavior and listening to speech is limited. The problem is that cues to deception are typically faint and unreliable. The aim for interviewers, therefore, is to ask questions that actively elicit and amplify verbal and nonverbal cues to deceit. We present an innovative lie detection perspective based on cognitive load, demonstrating that it is possible to ask questions that raise cognitive load more in liars than in truth tellers. This cognitive lie detection perspective consists of two approaches. The imposing-cognitive-load approach aims to make the interview setting more difficult for interviewees. We argue that this affects liars more than truth tellers, resulting in more, and more blatant, cues to deceit. The strategic-questioning approach examines different ways of questioning that elicit the most differential responses between truth tellers and liars.

To act truthfully: Nonverbal behaviour and strategies during a police interrogation

Abstract In an experiment, nonverbal indicators of deception in police interrogations of mock crimes were examined. Both vocal and nonvocal behaviours were scored. Thirty participants were subjected to long interrogations (over 9 minutes) conducted by 30 experienced police officers, asked to interrogate as they normally do. Although the liars reported being significantly more nervous, and found the task more strenuous than the truth tellers, no differences in the nonverbal behaviours scored were found. In an analysis of the strategies employed, both truth tellers and liars were found to try to not make excess movements. The principal verbal content strategy for the liars was to keep the story simple, and for truth tellers to keep the story real. The reasons why, in this demanding situation, the truth tellers and liars could not be distinguished by their nonverbal behaviour are discussed.

Police officers' lie detection accuracy: interrogating freely versus observing video

The study investigated experienced police officers’ (N = 30) lie detection accuracy. Each police officer conducted an interrogation of a college student acting as a suspect either guilty or innocent of a mock crime and made a veracity judgment of the suspect. The police officers had the opportunity to conduct the interrogation in the manner of their own choice. The lie detection accuracy of these police officers was compared to that of police officers judging videotaped versions of the interrogations. The police officers failed to detect deception better than chance. There was no difference in accuracy between police officers interrogating live and observing video. The interrogators reported to rely on verbal content more when interrogating than when watching video. It seems as though police officers have a difficult time detecting deception not only in passive contexts but also in active ones.For centuries, philosophers have pondered on the nature of human deception (see e.g., Bok, 1989). However, the scientific approach to human deception is far younger. For some decades, psychologists and scholars within the domain of communication have studied deception as a phenomenon of interpersonal relations (Ekman, 2001). Researchers have also focused on the nature of deception in applied contexts, such as in a forensic one (Granhag & Stromwall, 2004). In the legal system, professionals such as police officers and judges frequently face the task of having to judge the veracity of a person, be it a witness, alleged crime victim or a suspect. These judgments can be of utmost importance in the legal process, and the outcome of the judgments can have farreaching consequences for the person being judged. Detection of deception in the legal system is the focus of the present thesis. More specifically, I will examine the detection of deception in the context of interrogations, with a special focus on the effects of strategic use of the available evidence. Before summarizing the four empirical studies on this topic, I will provide an overview of the research on deception, and describe the relevant literature on interrogating suspects.

Social influences on reality-monitoring decisions.

A modified Asch (1951) conformity paradigm was used to study the impact of social influence on reality-monitoring decisions about new items. Subjects studied pictures of some objects and imagined others. In a later test phase, they judged whether items had been perceived in the study phase, had been imagined, or were new. Critically, for some items, the subjects were informed of a confederate’s response before rendering a judgment. Although the confederate was always correct when they responded to old items, for new items, the confederate respondedperceived, imagined, ornew, or did not respond (baseline). In two experiments, we show that memory for new items was influenced by an erroneous response of the confederate. Social conformity was reduced by undermining the credibility of the confederate (Experiments 1A and 1B), and the confederate’s influence was evident even after there was only a 20-min delay between study and test (Experiment 2), when the subjects were 87% accurate on new baseline items. These experiments reveal the power of social influence on realitymonitoring accuracy and confidence.

Impression and Information Management: On the Strategic Self- Regulation of Innocent and Guilty Suspects

The aim of this study was to increase understanding of the psychology of deception by mapping the reasoning of guilty and innocent mock suspects who deny a transgression. Based on previous research, we proposed that suspects will engage in two major forms of regulation: impression management, which requires the purposeful control of nonverbal and demeanor cues; and information management which involves the regulation and manipulation of speech content to provide a statement of denial. We predicted that truth tellers and liars would both be engaged in impression management, but that that they would differ in the extent to which they will engage in information management. The results supported this prediction: liars and truth tellers reported planning demeanor to the same extent, but differed in the extent to which they reported planning the content of their statement. Self-reported strategies regarding nonverbal behavior were similar for liars and truth tellers, while strategies regarding information differed markedly.

Strategic Use of Evidence During Investigative Interviews: The State of the Science

Abstract This chapter describes the Strategic Use of Evidence (SUE) technique – an interview method aimed at eliciting cues to deception, and thereby improving the chances of correct judgments of deception and truth. The chapter begins with a general overview of research on deception and its detection, in order to provide a context for the SUE technique. The psychological foundations of the technique are described, with a particular focus on suspects’ counter-interrogation strategies. We then review the empirical research on the SUE technique, in order to illustrate how the principles of the SUE technique can be translated into interview tactics. We also describe how these tactics produce different verbal responses from lying and truth-telling suspects, and how these cues can be utilized by lie-catchers in order to detect deception. Finally, we will provide a meta-analysis of the available research on the SUE technique.