Although microexpressions are analogous to longer-lasting ones in many ways, it is in their differences that much of the latest exciting science dwells.
Humintell’s Drs. David Matsumoto and Hyisung Hwang recently published an analysis of a major study, Shen et al. (2016), which sought to contrast fleeting microexpressions from those that lasted longer than 200 milliseconds. This analysis helps situate readers into the contemporary research on microexpressions and the importance of seeing them as a discrete phenomenon from longer-lasting expressions.
Shen et al. found that microexpressions, i.e. those that only lasted 40 to 120 milliseconds, were perceived quite similarly but were perceived quite distinctly from expressions which lasted longer. Of course, longer is relative here at only 200 milliseconds!
These findings, as Drs. Matsumoto and Hwang contend, have four major implications on the study of emotions and microexpressions.
The first of these is the importance of the 200 millisecond threshold. This fits well with research Drs. Matsumoto and Hwang completed two decades ago which emphasized that that once an expression is held for 200 ms it tends to be processed in observers’ short-term memories. This is one of the crucial distinction between everyday expressions and the more fleeting and unconscious microexpressions which Humintell studies.
Both this study and Humintell’s work support a definition of microexpressions that includes only those expressions which occur more quickly than half a second. While this has been controversial in the literature for some time, it seems clear that around this threshold stand distinctive psychological phenomena. Another interesting thing to note: Humintell was prescient in this by defining microexpressions more than a decade ago as those that occurred less than half a second. Humintell’s definition has been different from claims used by others that are not validated.
Second, this research contributes to the importance of finding neurological correlates to the perception of microexpressions. This has been extensively studied for longer-lasting facial expressions, but only a handful of studies have looked at the neurological reaction to fleeting microexpressions.
Shen et al. found that even hard-wired universal emotions, which we know have a significant biological basis, are still processed through culturally-taught rules, values, and associations, even when processing microexpressions.
Third, these neurological correlates also show how distinctive microexpressions are. Shen et al.’s research concluded that the neurological correlates for microexpressions differ significantly from longer lasting expressions. This leads to lasting questions about how expression duration can be used to study different types of expressions, such as the difference between voluntary or involuntary expressions, for instance.
Finally, this study and many others contribute to a growing field that seeks to understand deception detection. Microexpressions can often betray those seeking to lie. The ability to see those microexpressions is hard and demands training or practice. Still, it is important to note that individual differences, such as personality characteristics, can make this harder or easier.
Overall, this piece is an important addition to a growing body of literature seeking to understand microexpressions and their ramifications for deception detection.
We are very interested to hear what you think! What do you find compelling in terms of future questions? Where would you drive this research if you could? What do you think about these assertions?