Facially impaired man versus chimpanzee: a within-primate differentiation effect.

66 women, French students enrolled in a course, evaluated the presumed behavioural identity of a man whose face was severely deformed as observed in a photograph and evaluated the presumed behavioural identity of a chimpanzee whose face was also observed in a photograph. The behavioural targets referred to five areas of sexuality, to copulate, to masturbate, and to experience sexual pleasure with another; technology to garden, to prepare a meal, and to scavenge for plants; physiology to digest food to form hormones, and to perspire; social interactions: to converse with another, to do a favour for another, and to imitate; and cognition: to count up to ten, to remember recent events, and to use a stick as lever. The experiment had a 2 (entity: human's face versus chimpanzee's face) x 2 (presentation-order: man then chimpanzee versus the opposite order) experimental design with 33 subjects per cell. As predicted, the main effect of the presentation-order factor and the two-way interaction were significant for three target behaviors (to converse with another, to prepare a meal; and to copulate). The within-primate differentiation effect was explained in terms of motivation to preserve the identity of both the man and the chimpanzee.