Biology and Philosophy Vol. 19(no.1):111-126. 2004 Short description: What does the capacity to recognize self by mirrors tell about self-consciousness? Abstract: Research on mirror self-recognition where animals are observed for mirror-guided self-directed behaviour has predominated the empirical approach to self-awareness in nonhuman primates. The ability to direct behaviour to previously unseen parts of the body such as the inside of the mouth, or grooming the eye by aid of mirrors has been interpreted as recognition of self and evidence of a self-concept. Three decades of research has revealed that contrary to monkeys, most great apes (humans, common chimpanzees, pygmy chimpanzees and orangutans but not the gorilla) have convincingly displayed the capacity to recognize self by mirrors. The putative discontinuity in phylogeny of the ability suggests the existence of a so-called cognitive gap between great apes and the rest of the animal kingdom. However, methodological and theoretical inconsistencies regarding the empirical approach prevail. For instance, the observation of self-directed behaviour might not be as straightforward as it seems. In addition, the interpretation of mirror self-recognition as an index of self-awareness is challenged by alternative explanations, raising doubt about some assumptions behind mirror self-recognition. To evaluate the significance of the test in discussions of the concept of self this paper presents and analyses some major arguments raised on the mirror task.