Both mirror self-recognition (MSR) and “true” or “representational” imitation are among a host of different abilities that emerge in human infants between 18 and 24 months of age, when mental representation develops (Piaget, 1952). Mental representation is the highest cognitive achievement of the sensorimotor period. We believe that this is the basis for the expression of both self-recognition and imitation; by considering comparative and developmental evidence we shall discuss some of the cognitive conditions for each. Several researchers have suggested that the ability to imitate is a necessary condition for the development of self-recognition in human infants (e.g., Baldwin, 1903; Kaye, 1982; Lewis & Brooks-Gunn, 1979; see also Gopnik & Meltzoff, SAAH10; Hart & Fegley, SAAH9). However, contrary to this position, one hypothesis of this chapter is that imitation is not necessary for the development of self-recognition.

We believe that the developmental and comparative approaches must be used together in order to specify cognitive conditions for self-recognition and imitation (Mitchell, 1987; Parker, 1990, 1991). It is particularly difficult to determine the cognitive prerequisites by studying children alone, because many complex behaviors appear concurrently within a very narrow time frame. Developmental study of closely related primate species may be required to isolate the factors that are important in the development of cognitively complex behaviors such as self-recognition and imitation (Antinucci, 1989; Parker, 1991). Therefore, we shall utilize developmental data collected from our closest genetic relatives, chimpanzees, to compare with developmental data from human primates.