The ability of an organism to recognise itself, most often referenced by recognition of the physical self. It is measured by observing people‚was reaction to their mirror image. Prior to the middle of the second year of life, the human infant does not show self-recognition. Of the great apes only chimpanzees, but not gorillas and orang-utans, appear to show self-recognition as defined by test, as do porpoises with a different testing procedure. Thus, as yet, it would not be appropriate to deny gorillas or orang-utans are able to recognise their own reflections on the one test, as there may be other tests that in fact enables them to do so. Self-recognition is one of the earliest markers of a human child‚was ability to make reference to itself, something referred to as the mental state of the idea of me
. See Self-concept