Do Marmosets (Callithris jacchus) Recognize Faces?

Abstract

In this study we aimed to test the face recognition abilities of the common marmoset (Callithrix jacchus) using a y-maze choice task. A number of theories suggest that the marmoset’s arboreal habitat, small size, and neuroanatomy may constrain their face recognition abilities, but empirical data is lacking. Our control condition demonstrates that marmosets have a significant preference for an attractive stimulus over an aversive one, which validates our paradigm and method of stimulus presentation. We next presented face stimuli in two different contexts, comparing a conspecific face to a phase scrambled face, and a conspecific face to a heterospecific face. The marmosets’ lack of a side preference in either condition suggests that they cannot recognize faces or use faces to distinguish conspecifics. In two more experiments, we presented sets of stimuli comparing a conspecific body motion stimulus to a phase-scrambled motion stimulus, and a conspecific body motion stimulus to a heterospecific body motion stimulus. In both conditions, the marmosets significantly preferred the conspecific body motion, which indicates that marmosets can likely recognize and respond to bodily motion and/or bodily features, and use this to distinguish conspecifics. Our data suggest that face processing may not be a pan-primate phenotype and is likely constrained by ecological, morphological, and neuroanatomical factors.