Introduction

The idea that private, covert information is subtly communicated in human facial expressions is popular in both the academic literature (e.g., the ‘micro-expression’) and the media (e.g., the television show ‘Lie to Me’). Yet, in 2005, when we began to scour the literature for evidence of involuntary aspects of emotional expression – and the contribution to identifying insincere emotional expressions – we found that it was surprisingly scarce. With the exception of genuine and false smiles (e.g., Ekman, Davidson and Friesen 1990; Frank, Ekman and Friesen 1993), little research had addressed even the most basic issues around involuntary aspects of emotional expression, including whether micro-expressions exist. In the decade since this realization, our research team has conducted the most comprehensive investigation of the manner in which emotional information is involuntarily communicated on the human face (e.g., Porter and ten Brinke 2008; ten Brinke and Porter 2012; ten Brinke et al. 2013), sometimes to the expresser's dismay. With the goal of solving some of the mysteries and resolving some of the controversies in this area, we have manually coded millions of frames of videotaped faces for both the presence of full expressions and specific, individual muscle movements. These tapes include expressions generated in both highly controlled, lab-based experiments and naturalistic ‘real-life’ emotional scenarios. Not only does this body of research represent our basic interest in this aspect of human communication, but also it was motivated by the practical implications of the results. Specifically, in observing the deleterious consequences that emotional deception can have in society, we hoped to learn how science might inform the practice of identifying insincere emotions. For example, in one study we found that psychopathic offenders are such good emotional actors that they successfully talk and cry their way out of parole hearings at a rate two and a half times higher than their more meritorious counterparts (Porter, ten Brinke and Wilson 2009). When we followed up on their performance in the community, they typically re-offended quickly and often in a heinous, violent fashion. The goal of this chapter is to explore the results of our and others’ research on the manifestations of voluntary and involuntary aspects of emotional expressions in everyday life and the manner in which they relate to the differentiation of sincere and insincere expressions.