The classification of facial expressions of emotion: a multidimensional-scaling approach.

Photographs (study 1) or line-drawing representations (study 2) of posed facial expressions and a list of emotion words (happiness, surprise, fear, disgust, anger, sadness, neutral) were presented to two groups of observers who were asked to match the photographs or line drawings, respectively, with the emotion categories provided. A multidimensional-scaling procedure was applied to the judgment data. Two dimensions were revealed; pleasantness--unpleasantness and upper-face--lower-face dominance. Furthermore, the similarity shown by the two-dimensional structures derived first from the judgments of photographs and second from the line drawings suggests that line drawings are a viable alternative to photographs in facial-expression research.