Recent research has indicated that the discreteness of emotions may be supported by language. However, how emotions become discretize as language is acquired has not been explored. In this paper, two categories of facial expression and emotion were assumed to support the discreteness of emotions, and the mechanism of their discretization through language development was discussed. Facial expression categories are likely to be modified by affective word labels after they are formed nonverbally. Affective categories are likely to be formed in childhood through the acquisition of affective words. Furthermore, a process may exist from infancy to childhood in which facial expression categories are linked to emotion categories, and facial expression categories are adjusted to correspond to affective words. In the process of the development of emotional discreteness, the categories of facial expressions and emotions are formed by language development. They are further linked by the development of automatic verbalization of what is seen and the development of processing that categorizes the facial expressions of others, based on the conceptualized emotions of the self.
