Voluntary facial expression of emotion: comparing congenitally blind with normally sighted encoders.

The ability of congenitally blind persons to produce voluntarily facial expressions of a number of emotions was compared with that of normally sighted individuals using both objective facial measurement and observer recognition. Results revealed that there were almost no significant differences between blind and sighted participants with respect to the number and type of facial action units produced. The portrayals of the blind participants were significantly more poorly recognized by observers than were those of the sighted participants (except for happiness). Correspondence analyses of the data showed differences between sighted and blind participants in the dimensional structure of the expressions (as based on the similarity among emotions with respect to both objective measurement and judgments). Overall, the data relavitize earlier conclusions on the facial expression of blind as compared with sighted persons and suggest specific hypotheses and procedures for further work in this area.