Final answer:
The self-concept emerges in early childhood, particularly by around 18 months, and continues to develop through adolescence and into adulthood. Recognition of oneself in a mirror is an early sign of self-awareness, with subsequent developments in elementary and adolescence critical for forming a robust self-concept.
Step-by-step explanation:
The sense of self, or the self-concept, emerges gradually during various stages of development. Initially, infants lack a self-concept; they cannot recognize themselves in a mirror. However, by about 18 months, during what is known as the toddlerhood stage, children start to develop self-awareness, as shown by their ability to recognize their own reflection in the mirror. This development was famously demonstrated in a study using the mirror test. As children grow into elementary school age, their self-concept continues to form as they establish autonomy, compare themselves to others, and start feeling competent when these comparisons are favorable.
Eventually, during adolescence, individuals undergo a critical period of self-concept development, seeking answers to questions like "Who am I?" and trying on different roles. Successful navigation through this stage results in a strong personal identity. Conversely, failure to establish a clear identity can lead to feelings of role confusion and a weak sense of self. This process of self-development continues into early adulthood, where a strong sense of self becomes fundamental for forming intimate relationships and avoiding feelings of isolation.
Throughout these developmental stages, interaction with others and societal influences contribute to shaping one's self-concept. The significance of social interaction in forming the self was highlighted by theorists such as George Herbert Mead, who suggested that we develop the ability to see ourselves through the eyes of others as we grow.