2008 Volume 26 Issue 2 Pages 179-185
We investigated whether both squirrel monkeys and humans utilize the same cues to identify individual faces of their own and other species as well as the faces between two species. The squirrel monkeys were trained to discriminate between two individual faces. They were then tested on all-erased probe trials with a variety of modified stimuli. The test stimuli were only some facial features of the training stimuli in Experiments 1 and 3, composite faces in Experiment 2, and whole-body images of both species in Experiment 3. We found that the monkeys can identify individual faces of their own species better than those of other species. The eyes had a significant effect on the discrimination of between faces of both species. Furthermore, unlike humans, monkeys could use the outer boundary of monkey faces. These results suggest that squirrel monkeys could utilize their faces for the discrimination of the individuals and between two species, also they may have two strategies for facial processing. This diversity of facial processing may be due to the difference in the role of faces in the two species.
