Caitlin, the mother of the original family brought to Carleton, was captivated by her own reflection when we introduced mirrors. After a few days, she would sometimes back away from the mirror until she could see her whole body in the mirror and then she would orient her sitting on an angle and look at herself for long periods of time. Some of the younger monkeys would only peek at their image and run away, most likely due to gaze aversion which is common to monkeys and generates fear from the direct gaze that is an unfortunate side effect of your mirror reflection. It was reported in prior studies that most apes and monkeys needed a little time with a mirror to habituate to such qualities in order to take behavioral measures to determine whether there was evidence of recognition of self. We did not do a "mark test" in our study because tamarins rarely groom their own faces, rather others groom them. So a low rate of touching a mark may not indicate a lack of recognition of self so much as it might just be the lack of motivation to self-groom one's face. Instead we coded behaviors in terms of types of interactions with the mirror and found good evidence for self-directed behavior and increased interest in the self image, as compared to pictures of other monkeys or videotapes shown of other monkeys. This was our first publication from the lab, after a hard-fought set of arguments to defend why we did not use the mark test. If interested, read this publication below, and a later review of many studies of self and other testing by the lab (Neiworth, 2009).
Read the published article on self-awareness (2001).
CITATION: Neiworth, J. J., Anders, S. L., & Parsons, R. R. (2001). Tracking responses related to self-recognition: a frequency comparison of responses to mirrors, photographs, and videotapes by cotton top tamanins (Saguinus oedipus). Journal of comparative psychology (Washington, D.C. : 1983), 115(4), 432–438.