Humans perceive facial expressions categorically, though physical features of emotions vary continuously. How do cat-egorical representations of facial expressions emerge or update? We explored how supervised and unsupervised learninginfluence emotion category boundaries. 91 children (6-8-years-old) and 105 adults categorized emotions varying along aneutral-angry continuum. Participants completed a supervised learning phase, which explicitly taught an emotion cate-gory boundary. Then, participants completed an unsupervised learning phase. Without feedback, participants categorizedexpressions sampled from statistical distributions that matched or did not match the distribution categorized during su-pervised learning. Participants learned the boundary via supervised learning, but responses rapidly shifted followingthe statistical distribution via unsupervised learning. Thus, participants quickly updated emotion categories, indicatingboundaries are highly context-sensitive. Such flexibility allows individuals to adjust across situations and organize re-sponses based on extant, versus explicitly taught, socio-emotional cues. Follow-up research explores how participantsadjust category boundaries for multiple individuals varying in expressivity.

How do children learn to categorize the facial configurations classically believed to represent basic emotions? Many stud-ies have examined when children are able to perceptually discriminate between emotional facial expressions and whenchildren are able to verbally label these expressions. However, while these studies provide important information aboutthe timeline of emotional development, they give less information about the nature of childrens category representationsfor different facial configurations. For instance, emotion concepts may emerge from childrens perceptions of facial con-figurations along the dimensions of valence and arousal. To evaluate how 3- to 7-year-old children categorize emotionconcepts, we had them sort facial configurations on a grid based on whether the people were feeling the same kind ofthing. We found that while both children and adults consistently sorted faces according to the dimensions of valence andarousal, sorting faces using discrete emotion categories emerged only gradually across development, with children notdemonstrating consistent use of emotion categories until approximately 5- to 6- years of age.

Perceivers view facial configurations as belonging to emotion categories, though the features of facial cues to emotionvary continuously. Little is understood about what factors beyond facial musculature influence these categorizations. Weinvestigated how an emoters gender influences how emotional cues are perceived. Eighty-four adults categorized morphedemotional faces of male and female models sampled from a neutral-angry continuum. Participants had a lower thresholdfor categorizing female faces as upset (X2=16.618, p¡.001), particularly for configurations that were closer to the angryend of the continuum. Even when provided explicit feedback on their responses, participants continued to be more likelyto identify a face as angry for female, as compared to male, models (X2=11.561, p¡.001). Therefore, judgments of emotionwere influenced by both the emotional cues displayed by a model and also the models identity. These results highlighthow the social context influences how individuals readand therefore respond toanger.

One challenge that children face when learning from others isthat social agents can behave in unpredictable ways. Socialagents may acquire—or fail to acquire—new information thatinfluences how they interact with the learner. Little is knownabout children’s sensitivity to these changes or howeffectively children update their own behavior in response.Participants (N = 129) searched for rewards while receivingsuggestions from a social agent. The suggestions changed inlevel of reliability over time. All children updated howheavily they weighted the cues after the change. However,younger children were more influenced by their initialexperience with the suggestions, indicating that youngerchildren may have more difficulty disengaging from socialinformation in uncertain learning environments.

Research over the past decades has demonstrated the explanatory power of emotions, feelings, motivations, moods, and other affective processes when trying to understand and predict how we think and behave. In this consensus article, we ask: has the increasingly recognized impact of affective phenomena ushered in a new era, the era of affectivism?