Facial expressions can be categorized along the upper-lower facial axis, from a perceptual perspective

A critical question, fundamental for building models of emotion, is how to categorize emotions. Previous studies have typically taken one two approaches: (a) they focused on the pre-perceptual visual cues, salient facial features or configurations were displayed; (b) post-perceptual affective experiences, emotions affected behavior. In this study, we attempted group at a peri-perceptual processing level: it well known that humans perceive different expressions differently, therefore, can classify into distinct categories in terms their perceptual similarities? Here, using novel non-lexical paradigm, assessed dissimilarities between 20 reaction times. Multidimensional-scaling analysis revealed organized predominantly along upper-lower face axis. Cluster behavioral data delineated three superordinate categories, and eye-tracking measurements validated these clustering results. Interestingly, be conceptualized according displays interact with acoustic communications: One comprises mouth features. They likely link species-specific vocalization, example, crying, laughing. The second diagnosing both eye regions. are not directly articulable but expressed prosodically, sad, angry. Expressions third also whole-face completely independent being blends more elementary expressions. We propose theoretical framework interpret tripartite division which expression subsets interpreted as successive phases an evolutionary chain.