A minimal ingroup advantage in emotion identification confidence

An ingroup disadvantage in recognizing micro-expressions

Micro-expression is a fleeting facial expression of emotion that usually occurs in high-stake situations and reveals the true emotion that a person tries to conceal. Due to its unique nature, recognizing micro-expression has great applications for fields like law enforcement, medical treatment, and national security. However, the psychological mechanism of micro-expression recognition is still poorly understood. In the present research, we sought to expand upon previous research to investigate whether the group membership of the expresser influences the recognition process of micro-expressions. By conducting two behavioral studies, we found that contrary to the widespread ingroup advantage found in macro-expression recognition, there was a robust ingroup disadvantage in micro-expression recognition instead. Specifically, in Study 1A and 1B, we found that participants were more accurate at recognizing the intense and subtle micro-expressions of their racial outgroups than those micro-expressions of their racial ingroups, and neither the training experience nor the duration of micro-expressions moderated this ingroup disadvantage. In Study 2A and 2B, we further found that mere social categorization alone was sufficient to elicit the ingroup disadvantage for the recognition of intense and subtle micro-expressions, and such an effect was also unaffected by the duration of micro-expressions. These results suggest that individuals spontaneously employ the social category information of others to recognize micro-expressions, and the ingroup disadvantage in micro-expression stems partly from motivated differential processing of ingroup micro-expressions.

The strain of unfamiliar conspecifics affects stress identification in rats

Humans show distinct social behaviours when we evaluate an individual as being a member of the same group and recognize social similarity to the individual. One example is more accurate identification of emotion in that individual. Our previous studies proposed that rats recognize social similarity to certain strains of unfamiliar rats. It is therefore possible that the strain of unfamiliar conspecifics affects stress identification in rats. Wistar subject rats were allowed to explore a pair of unfamiliar Wistar, Sprague-Dawley (SD), Long-Evans (LE), or Fischer344 (F344) stimulus rats. To induce differences in stress, one of the stimulus rats had received foot shocks immediately before the test. It was found that the subjects showed biased interaction towards the shocked Wistar and SD stimulus rats, but not toward the shocked LE or F344 stimulus rats. Subsequent experiments confirmed that the biased interaction towards the shocked Wistar and SD stimulus rats was driven by stress in these stimulus rats. In addition, the lack of biased interaction towards the shocked LE and F344 stimulus rats did not appear to be due to procedural reasons. The experiment using LE subject rats further confirmed that the shocked LE stimulus rats emitted distress signals. These results suggested that Wistar rats could identify stress in unfamiliar Wistar and SD rats, but not in unfamiliar LE or F344 rats. Therefore, rats appear to recognize social similarity to certain unfamiliar strains of rats.