A critical review of methodology and interpretation of mirror self-recognition research in nonhuman primates

In this paper we critically review conceptual and methodological issues of mirror self-exploration research. We conclude that: (1) mirror self-explora tion provides evidence for mirror self-recognition; (2) inter- and intraspe cies differences in terms of presence or absence of mirror self-recognition are not yet sufficiently clear, that is, whether its absence in species an d individuals is methodological (false negative with respect to trait) or o ntological (true negative with respect to trait) in nature; and (3) proposa ls of hypotheses to account phylogenetically for the existence of inter- an d intraspecies differences in mirror self-recognition are premature. Before hypotheses such as these are advanced, the impact of rearing conditions on mirror self-recognition should be examined further. (C) 1999 The Associati on for the Study of Animal Behaviour.