Md. Hauser et al., SELF-RECOGNITION IN PRIMATES - PHYLOGENY AND THE SALIENCE OF SPECIES-TYPICAL FEATURES, Proceedings of the National Academy of Sciences of the United Statesof America, 92(23), 1995, pp. 10811-10814
Self-recognition has been explored in nonlinguistic organisms by recor
ding whether individuals touch a dye-marked area on visually inaccessi
ble parts of their face while looking in a mirror or inspect parts of
their body while using the mirror's reflection. Only chimpanzees, gori
llas, orangutans, and humans over the age of approximately 2 years con
sistently evidence self-directed mirror-guided behavior without experi
menter training. To evaluate the inferred phylogenetic gap between hom
inoids and other animals, a modified dye-mark test was conducted with
cotton-top tamarins (Saguinus oedipus), a New World monkey species. Th
e white hair on the tamarins' head was color-dyed, thereby significant
ly altering a visually distinctive species-typical feature. Only indiv
iduals with dyed hair and prior mirror exposure touched their head whi
le looking in the mirror. They looked longer in the mirror than contro
ls, and some individuals used the mirror to observe visually inaccessi
ble body parts. Prior failures to pass the mirror test may have been d
ue to methodological problems, rather than to phylogenetic differences
in the capacity for self-recognition. Specifically, an individual's s
ensitivity to experimentally modified parts of its body may depend cru
cially on the relative saliency of the modified part (e.g., face versu
s hair). Moreover, and in contrast to previous claims, we suggest that
the mirror test may not be sufficient for assessing the concept of se
lf or mental state attribution in nonlinguistic organisms.