Dynamics of Identity Development in Adolescence: A Decade in Review.

One of the key developmental tasks in adolescence is to develop a coherent identity. The current review addresses progress in the field of identity research between the years 2010 and 2020. Synthesizing research on the development of identity, we show that identity development during adolescence and early adulthood is characterized by both systematic maturation and substantial stability. This review discusses the role of life events and transitions for identity and the role of micro-processes and narrative processes as a potential mechanisms of personal identity development change. It provides an overview of the linkages between identity development and developmental outcomes, specifically paying attention to within-person processes. It additionally discusses how identity development takes place in the context of close relationships.

Daily Identity Dynamics in Adolescence Shaping Identity in Emerging Adulthood: An 11-Year Longitudinal Study on Continuity in Development.

According to identity theory, short-term day-to-day identity exploration and commitment processes are the building blocks for long-term development of stable commitments in emerging adulthood. This key assumption was tested in a longitudinal study including 494 individuals (43% girls, Mage T1 = 13.31 years, range 11.01-14.86 years) who were followed from adolescence into emerging adulthood, covering ages 13 to 24 years. In the first five years, adolescents reported on their daily identity processes (i.e., commitment, reconsideration and in-depth exploration) across 75 assessment days. Subsequently, they reported on their identity across four (bi-) annual waves in emerging adulthood. Findings confirmed the existence of a dual-cycle process model of identity formation and identity maintenance that operated at the within-person level across days during adolescence. Moreover, individual differences in these short-term identity processes in adolescence predicted individual differences in identity development in emerging adulthood. Specifically, those adolescents with low daily commitment levels, and high levels of identity reconsideration were more likely to maintain weak identity commitments and high identity uncertainty in emerging adulthood. Also, those adolescents characterized by stronger daily changes in identity commitments and continuing day-to-day identity uncertainty maintained the highest identity uncertainty in emerging adulthood. These results support the view of continuity in identity development from short-term daily identity dynamics in adolescence to long-term identity development in emerging adulthood.

Identity Structure and Processes in Adolescence: Examining the Directionality of Between- and Within-Person Associations.

Developing a stable and coherent identity structure (i.e., a synthesized sense of self that can support self-directed decision making) represents a lifelong task. A person's identity structure is continually revised through ongoing processes of identity exploration and commitment. However, longitudinal studies linking identity structure to identity processes are largely lacking. The present three-wave longitudinal study among 530 Flemish high school students [50.6% female; Mage = 15; SD = 1.85; age range = 11-19 years] examined the directionality of both between- and within-person associations linking identity synthesis and confusion to identity exploration and commitment processes. Between-person cross-lagged models indicated that adolescents who scored high on identity synthesis relative to their peers also scored high on proactive exploration and commitment processes, and low on ruminative exploration one year later, again relative to their peers. Adolescents who scored high on identity confusion relative to their peers also scored high on ruminative exploration one year later, again relative to their peers. With respect to effects of identity processes on identity structure, adolescents who scored high on identification with commitment relative to their peers also scored low on identity confusion one year later. Within-person cross-lagged models indicated that, when adolescents scored high on identity synthesis relative to their own average score, they reported increased proactive exploration processes one year later. In general, reaching a degree of identity synthesis appears to represent a prerequisite for proactive identity exploration at both the between- and within-person levels.

Goal-Directed Correlates and Neurobiological Underpinnings of Adolescent Identity: A Multimethod Multisample Longitudinal Approach.

This multimethod multisample longitudinal study examined how neurological substrates associated with goal directedness and information seeking are related to adolescents' identity. Self-reported data on goal-directedness were collected across three biannual waves in Study 1. Identity was measured one wave later. Study 1 design and measurements were repeated in Study 2 and extended with structural brain data (nucleus accumbens [NAcc] and prefrontal cortex gray matter volume [PFC]), collected across three biannual waves. Study 1 included 497 adolescents (Mage T1  = 13.03 years) and Study 2 included 131 adolescents (Mage T1  = 14.69 years). Using latent growth curve models, goal directedness, NAcc, and PFC volume predicted a stronger identity one wave later. These findings provide crucial new insights in the underlying neurobiological architecture of identity.

Clear Self, Better Relationships: Adolescents' Self-Concept Clarity and Relationship Quality With Parents and Peers Across 5 Years.

This study examined reciprocal associations between adolescents' self-concept clarity (SCC) and their relationship quality with parents and best friends in a five-wave longitudinal study from age 13 to 18 years. In all, 497 adolescents (57% boys) reported on their SCC and all informants (i.e., adolescents, both parents, and adolescents' best friends) reported on support and negative interaction. Within-person cross-lagged analyses provided systematic evidence for both parent effects and child effects, with the direction of effects being strongly dependent on the relational context. For example, higher maternal support predicted higher adolescent SCC, supporting a parent effects perspective, whereas higher SCC predicted lower paternal negative interaction, supporting a child effects perspective. Peer effects on adolescent SCC were not consistently found across adolescent and best friend reports.

Child personality facets and overreactive parenting as predictors of aggression and rule-breaking trajectories from childhood to adolescence.

This study examined trajectories of aggression and rule breaking during the transition from childhood to adolescence (ages 9-15), and determined whether these trajectories were predicted by lower order personality facets, overreactive parenting, and their interaction. At three time points separated by 2-year intervals, mothers and fathers reported on their children's aggression and rule breaking (N = 290, M age = 8.8 years at Time 1). At Time 1, parents reported on their children's personality traits and their own overreactivity. Growth mixture modeling identified three aggression trajectories (low decreasing, high decreasing, and high increasing) and two rule-breaking trajectories (low and high). Lower optimism and compliance and higher energy predicted trajectories for both aggression and rule breaking, whereas higher expressiveness and irritability and lower orderliness and perseverance were unique risk factors for increasing aggression into adolescence. Lower concentration was a unique risk factor for increasing rule breaking. Parental overreactivity predicted higher trajectories of aggression but not rule breaking. Only two Trait × Overreactivity interactions were found. Our results indicate that personality facets could differentiate children at risk for different developmental trajectories of aggression and rule breaking.

Beyond the average brain: individual differences in social brain development are associated with friendship quality.

We tested whether adolescents differ from each other in the structural development of the social brain and whether individual differences in social brain development predicted variability in friendship quality development. Adolescents (N = 299, Mage T1 = 13.98 years) were followed across three biannual waves. We analysed self-reported friendship quality with the best friend at T1 and T3, and bilateral measures of surface area and cortical thickness of the medial prefrontal cortex (mPFC), posterior superior temporal sulcus (pSTS), temporoparietal junction (TPJ) and precuneus across all waves. At the group level, growth curve models confirmed non-linear decreases of surface area and cortical thickness in social brain regions. We identified substantial individual differences in levels and change rates of social brain regions, especially for surface area of the mPFC, pSTS and TPJ. Change rates of cortical thickness varied less between persons. Higher levels of mPFC surface area and cortical thickness predicted stronger increases in friendship quality over time. Moreover, faster cortical thinning of mPFC surface area predicted a stronger increase in friendship quality. Higher levels of TPJ cortical thickness predicted lower friendship quality. Together, our results indicate heterogeneity in social brain development and how this variability uniquely predicts friendship quality development.

Mood and emotional reactivity of adolescents during the COVID-19 pandemic: short-term and long-term effects and the impact of social and socioeconomic stressors.

Adolescence is a formative period for socio-emotional development which is threatened by the COVID-19 pandemic. The current longitudinal study examined two aims: (1) the short- and long-term effects of the pandemic on young people's mood (i.e. vigor, tension, and depression levels) and emotional reactivity (i.e. fluctuations in daily mood), and (2) the impact of stressors on mood, emotional reactivity, self-oriented (i.e. maladaptive behavior towards COVID-19 rules) and other-benefitting behaviors (i.e. behavior aimed at helping and comforting others). We conducted an online two-week daily diary study among 462 Dutch adolescents (Mage = 15.27 years, 64% females) and 371 young adults (Mage = 21.49 years, 81% females) in May 2020, with a follow-up in November 2020 (N = 238 and 231, respectively adolescents and young adults). In May 2020, young adults and older relative to younger adolescents showed higher levels and more fluctuations in tension and depression and lower levels of vigor. Vigor levels decreased and tension and depression levels increased between May 2020 and November 2020, especially for younger adolescents. There were positive associations between instability of negative emotions (i.e. tension and depression fluctuations) and the exposure to stressors (i.e. family stress and inequality of online homeschooling) in the adolescent sample. Together, this study demonstrates vulnerability regarding young people's mood and emotional reactivity during the COVID-19 pandemic, especially for adolescents who experience more stressors.

Modeling Individual Differences in Brain Development.

Within the field of developmental cognitive neuroscience, there is an increasing interest in studying individual differences in human brain development in order to predict mental health outcomes. So far, however, most longitudinal neuroimaging studies focus on group-level estimates. In this review, we highlight longitudinal neuroimaging studies that have moved beyond group-level estimates to illustrate the heterogeneity in patterns of brain development. We provide practical methodological recommendations on how longitudinal neuroimaging datasets can be used to understand heterogeneity in human brain development. Finally, we address how taking an individual-differences approach in developmental neuroimaging studies could advance our understanding of why some individuals develop mental health disorders.

Longitudinal associations between structural prefrontal cortex and nucleus accumbens development and daily identity formation processes across adolescence.

We tested whether adolescents with daily high identity uncertainty showed differential structural brain development across adolescence and young adulthood. Participants (N = 150, MageT1 15.92 years) were followed across three waves, covering 4 years. Self-reported daily educational identity and structural brain data of lateral prefrontal cortex (lPFC)/anterior cingulate cortex (ACC), medial PFC, and nucleus accumbens (NAcc) was collected across three waves. All hypotheses were pre-registered. Latent class growth analyses confirmed 2 identity subgroups: an identity synthesis class (characterized by strong commitments, and low uncertainty), and an identity moratorium class (high daily identity uncertainty). Latent growth curve models revealed, on average, delayed maturation of the lateral PFC/ACC and medial PFC and stable NAcc. Yet, adolescents in identity moratorium showed lower levels and less decline in NAcc gray matter volume. Lateral PFC/ACC and medial PFC trajectories did not differ between identity subgroups. Exploratory analyses revealed that adolescents with higher baseline levels and delayed maturation of lateral PFC/ACC and medial PFC gray matter volume, surface area, and cortical thickness reported higher baseline levels and stronger increases of in-depth exploration. These results provide insight into how individual differences in brain development relate to fluctuations in educational identity development across adolescence and young adulthood.

Linking identity and depressive symptoms across adolescence: A multisample longitudinal study testing within-person effects.

This multisample longitudinal study examined the directionality of effects between identity exploration and commitment processes and depressive symptoms across adolescence. We compared two theoretical perspectives. According to the vulnerability model, identity uncertainty predicts depressive symptoms, whereas the scar model holds that depressive symptoms play into identity uncertainty. In investigating both models, we examined reciprocal within-person associations in Study 1 (N = 497, Mage Time 1 [T1] = 14.03 years, comprising five annual waves) and Study 2 (N = 1,022, Mage T1 = 15.80 years, comprising four annual waves). To this end, we applied the random-intercept cross-lagged panel model (RI-CLPM) in both studies. Results supported the vulnerability model across Studies 1 and 2. Specifically, within-person increasing reconsideration of commitment (Study 1) and ruminative exploration (Study 2) predicted a within-person increase in depressive symptoms 1 year later, but not vice versa. Commitment processes did not predict depressive symptoms at the within-person level. Our findings indicate that maladaptive exploration processes of identity formation play a particularly important role in the development of depressive symptoms at the within-person level. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Identity uncertainty and commitment making across adolescence: Five-year within-person associations using daily identity reports.

A central assumption of identity theory is that adolescents reconsider current identity commitments and explore identity alternatives before they make new commitments in various identity domains (Erikson, 1968; Marcia, 1966). Yet, little empirical evidence is available on how commitment and exploration dynamics of identity formation affect each other across adolescence at the within-person level. Therefore, the current study (N = 494, Mage Time 1 = 13.3 years) examined reciprocal within-person longitudinal linkages between adolescents' identity exploration and identity commitment making in the interpersonal and educational identity domains. For this purpose, we constructed a multilevel type cross-lagged panel model from early to late adolescence (i.e., across 5 successive years). Results supported Erikson's (1968) hypothesis that adolescents reconsider current identity commitments and explore alternatives before they make strong commitments within the interpersonal identity domain across early to late adolescence. Within the educational identity domain, increasing identity commitment level and commitment fluctuations predicted less identity reconsideration over time. Our findings support identity theory, but indicate that the processes of identity formation might differ depending on the identity domain. (PsycINFO Database Record

The quest for identity in adolescence: Heterogeneity in daily identity formation and psychosocial adjustment across 5 years.

Identity formation is one of the key developmental tasks in adolescence. According to Erikson (1968) experiencing identity uncertainty is normative in adolescence. However, empirical studies investigating identity uncertainty on a daily basis are lacking. Hence, studying individual differences in daily certainty (i.e., identity commitment levels) and uncertainty (i.e., identity commitment fluctuations and identity reconsideration) in the identity formation process may advance our knowledge about the extent to which adolescents' identity uncertainty is part of normative identity development. Therefore, this longitudinal study examined heterogeneity in certainty and uncertainty dynamics of adolescents' daily identity formation using a longitudinal microlevel approach. Dutch adolescents (N = 494; Mage = 13.03 years at T1; 56.7% boys) reported on 2 key dimensions of identity formation (i.e., commitment and reconsideration) in both the educational and interpersonal domain on a daily basis for 3 weeks within 1 year, across 5 successive years. Multivariate latent class growth analyses suggested both in the educational and interpersonal identity domain a class of adolescents displaying a "crisis-like" identity formation process, and an "identity synthesis" class. Classes revealed differential development of (global and school) anxiety, aggression, and best friend support. Taken together, the present study confirmed Erikson's notion that experiencing daily identity uncertainty is common during adolescence. However, a substantial amount of adolescents also showed a process toward identity maturation already during adolescence. (PsycINFO Database Record

Assessment of identity during adolescence using daily diary methods: Measurement invariance across time and sex.

The aim of this study was to assess measurement invariance of adolescents' daily reports on identity across time and sex. Adolescents (N = 497; mean age = 13.32 years at Time 1, 56.7% boys) from the general population reported on their identity commitments, exploration in depth and reconsideration on a daily basis for 3 weeks within 1 year across 5 years. We used the single-item version of the Utrecht Management of Identity Commitments Scale (UMICS; Klimstra et al., 2010), a broad measure of identity-formation processes covering both interpersonal and educational identity domains. This study tested configural, metric, scalar, and strict measurement invariance across days within weeks, across sex, across weeks within years, and across years. Results indicated that daily diary reports show strict measurement invariance across days, across weeks within years, across years, and across boys and girls. These results support the use of daily diary methods to assess identity at various time intervals ranging from days to years and across sex. Results are discussed with regard to future implications to study identity processes, both on smaller and larger time intervals. (PsycINFO Database Record