Typically-developing children (n = 38, 24 girls) completed data collection at two visits (separated by 36 ± 10 months), and provided high-quality fMRI and behavioral data at both time points (average age = 10.0 ± 0.57 and DAPT nmr 13.0 ± 0.67 years at T1 and

T2, respectively). Participants and their parents provided written informed assent/consent according to guidelines specified by the Institutional Review Board at UCLA. Participants had no history of significant medical, psychiatric, or neurological disorders. As a group, participants were ethnically and socioeconomically diverse. Fifty percent of participants were White, 25% Hispanic, 7.5% Asian, 5% Black, 5% Native American, and 2.5% Pacific Islander; 15% of this sample reported being multiethnic, including one participant (2.5%) who primarily identified as multiethnic. Parent reports of annual household income ranged from <$25,000 to >$400,000 (with an average income Akt inhibitor bracket of $100,000–$120,000). Full-scale IQ assessed by the Wechsler Intelligence Scale for Children (Wechsler, 1949) ranged from 86 to 144

(with an average IQ of 118). The Pubertal Development Scale (PDS; Petersen et al., 1988) was completed at both time points; on this measure, participants self-report visible development of secondary sexual characteristics. There was a highly significant increase from T1 to T2 on the PDS [Ms = 1.58 and 2.56 at T1 and T2, respectively; t(1, 37) = 9.43, p ∼ 0]. According to methods outlined by Shirtcliff et al. (2009),

the PDS was transformed into values corresponding with Tanner stages on a gender-specific basis. These transformations suggested that the average level of development was similar between girls and boys in late childhood (T1 Ms = 1.96 and 1.93 for girls and boys, respectively, indicating early pubertal status). By early adolescence, the girls were slightly more advanced (T2 Ms = 3.73 and 3.07 for girls and boys, indicating mid-to-late and midpubertal status, respectively). Participants also filled out the RPI Scale (Steinberg and Monahan, 2007), and indicators of risk behavior and delinquency as utilized in the Lerner 4-H Study of Positive Youth Development Survey Non-specific serine/threonine protein kinase (IRBD; Gestsdóttir and Lerner, 2007). The RPI is a self-report measure of resistance to peer influence that has been validated in nearly 4000 individuals ranging in age from 10–30 and varying in ethnicity and socioeconomic status. Important advantages of the RPI are that it targets primarily neutral, not antisocial or deviant influences, and minimizes socially desirable responding. On average, resistance to peer influence is lowest in late childhood and early adolescence, but then increases linearly beginning around 14 years of age. Our study thus presumably investigated the window of maximum susceptibility.