Becoming Certain of the Self: Longitudinal Studies Into the Dynamics of (Daily) Identity Development

‘Who am I?’ and ‘Who do I want to become?’ are critical questions adolescents ask themselves. This search for a personal identity can be very stressful and can strongly impact adolescents’ well-being. Hence, it is vital to gain insight into how adolescents explore and develop their identity and to find out why some adolescents are able to develop a clear sense of who they are whereas others remain highly uncertain about their identity. This dissertation aimed to provide more insight into how adolescents form their identity on a day-to-day basis as well as across years. We examined identity processes from ages 13 through 24 years. Given that identity development does not take place in a void, the longitudinal studies in this dissertation also examined how key neurobiological, psychological, and social processes contributed to identity formation processes over time. Findings in this dissertation reveal that establishing a strong identity is a complex developmental task that is embedded in adolescents’ daily lives. Also, results indicate that the adolescent brain is involved in the development of a strong identity over time. Finally, findings highlight that establishing a strong identity can buffer against the development of psychopathology and improves social relationships. Hence, a strong identity serves as an important psychological resource that guides adolescents in their daily lives.