Abstract # 186:

Scheduled for Sunday, September 18, 2011 07:00 PM-09:00 PM: Session 23 (Salon G (Sixth Floor)) Poster Presentation


T. L. Rubin and F. de Waal
Living Links, Yerkes National Primate Research Center and Department of Psychology, Emory University, 954 N. Gatewood Road, Atlanta, GA 30322, USA

Facial expressions are important signals for primates that convey critical information about the internal state of individuals. Misunderstanding these signals can have dire consequences, e.g., aggression or missed mating opportunities. Tufted capuchins have demonstrated the capacity to individually discriminate conspecific faces as well as categorize faces as belonging to an in-group or out-group, but no testing has been done to determine their ability to discriminate emotional expressions. We examined whether tufted capuchins discriminate between neutral and emotional expressions. Data were collected from four adult monkeys using an oddity task on touch-sensitive computers. Four images of conspecific faces were presented: three distinct images of a neutral expression and one image depicting either an open-mouth threat (non-affiliative) or an eyebrow flash (affiliative). A two-tailed one sample t-test revealed that the subjects discriminated emotional expressions from neutral expressions significantly above chance (t(3) = 10.58; P < 0.01). A two-tailed paired samples t-test revealed that they discriminated the open mouth threat significantly better than the eyebrow flash (t(3) = 4.34; P < 0.05). In order to control for memorization of the stimuli, subjects received a transfer test with novel images. In the transfer test, the subjects continued to discriminate emotional expressions from neutral expressions above chance (t(3) = 23.99; P < 0.0001). These results suggest that discriminating emotional facial expressions is an important aspect of tufted capuchin communication.