 At what age can human infants be credited with self-consciousness? Is self-consciousness present beyond homo sapiens? Some theorists, for example Bermúdez (1998), claim that various forms of perceptual experience constitute a non-conceptual form of self-consciousness (see  §3).  Others, for example Rosenthal (2005), claim that phenomenal consciousness entails self-consciousness. If either view is correct then self-consciousness, of some kind, can plausibly be attributed to creatures other than adult humans. But when it comes to more sophisticated forms of self-awareness, matters are less clear. What is required is some empirical criterion for judging a creature self-conscious even if, as with infants and non-human animals, they are unable to provide evidence via their use of the first-person pronoun. Such evidence, if available, may reasonably be thought to shed light on both the phylogenetic and ontogenetic development of self-consciousness (Ferrari &amp; Sternberg 1998; Terrace &amp; Metcalfe 2005; see the entries on  animal consciousness  and  animal cognition).