Achieving identity, in the sense of

Achieving identity, in the sense of acquiring a set of
beliefs about the self (a self-schema), is one of the central
developmental tasks of a social being (Lewis, 1990).
It progresses through several levels of complexity, and
continues to develop through the lifespan (see Chapters
38 and 39).
During the first few months, the baby gradually
distinguishes itself from its environment and from
other people, and develops a sense of continuity through
time (the existential self). But at this stage, the infant’s
self-knowledge is comparable to that of other species
(such as monkeys). What makes human self-knowledge
distinctive is becoming aware that we have it – we’re
conscious of our existence and uniqueness (Buss, 1992).
According to Maccoby (1980), babies are able to
distinguish between themselves and others on two counts:
1. Their own fingers hurt when bitten (but they don’t
have any such sensations when they’re biting their
rattle or their mother’s fingers).
2. Probably quite early in life, they begin to associate
feelings from their own body movements with the
sight of their own limbs and the sounds of their own
cries. These sense impressions are bound together into
a cluster that defines the bodily self, so this is probably
the first aspect of the self-concept to develop.
Other aspects of the self-concept develop by degrees,
but there seem to be fairly clearly defined stages of
development. Young children may know their own
names and understand the limits of their own bodies, and yet be unable to think about themselves as coherent
entities. So, self-awareness/self-consciousness develops
very gradually.
According to Piaget, an awareness of self comes
through the gradual process ofadaptation to the environment
(see Chapter 34). As the child explores objects and
accommodates to them (thus developing new sensorimotor
schemas), it simultaneously discovers aspects of its self. For
example, trying to put a large block into its mouth and
finding that it won’t fit is a lesson in selfhood, as well as
a lesson about the world of objects.