Judgments of subtle facial expressions of emotion.

Most studies on judgments of facial expressions of emotion have primarily utilized prototypical, high-intensity expressions. This paper examines judgments of subtle facial expressions of emotion, including not only low-intensity versions of full-face prototypes but also variants of those prototypes. A dynamic paradigm was used in which observers were shown a neutral expression followed by the target expression to judge, and then the neutral expression again, allowing for a simulation of the emergence of the expression from and then return to a baseline. We also examined how signal and intensity clarities of the expressions (explained more fully in the Introduction) were associated with judgment agreement levels. Low-intensity, full-face prototypical expressions of emotion were judged as the intended emotion at rates significantly greater than chance. A number of the proposed variants were also judged as the intended emotions. Both signal and intensity clarities were individually associated with agreement rates; when their interrelationships were taken into account, signal clarity independently predicted agreement rates but intensity clarity did not. The presence or absence of specific muscles appeared to be more important to agreement rates than their intensity levels, with the exception of the intensity of zygomatic major, which was positively correlated with agreement rates for judgments of joy.