Internal and External Validity of Self-Report and Parent-Report Measures of Sluggish Cognitive Tempo in South Korean Adolescents

This study evaluated the internal and external validity of self-report and parent-report measures of sluggish cognitive tempo (SCT) in South Korean adolescents. Adolescents (N = 469, ages 13–17 years; 50.2% boys) completed self-report measures of SCT and attention-deficit/hyperactivity disorder inattention (ADHD-IN) in addition to measures of internalizing and externalizing psychopathology, social problems, and grades. Parents rated adolescents on SCT, ADHD-IN, internalizing and externalizing psychopathology, and social problems. Using adolescent self-report, 11 of 15 SCT symptoms showed convergent and discriminant validity with ADHD-IN. Using parent-report, all 15 SCT symptoms showed convergent and discriminant validity with ADHD-IN. For within source analyses, SCT showed unique and stronger associations than ADHD-IN with internalizing psychopathology whereas ADHD-IN showed unique and stronger associations than SCT with externalizing psychopathology. SCT and ADHD-IN showed similar unique associations with social problems, whereas ADHD-IN was more strongly related than SCT to grades. Across source analyses also supported the differential unique associations of SCT and ADHD-IN with internalizing and externalizing psychopathologies. This study provides initial evidence for the internal and external validity of SCT with South Korean adolescents, extending support for the transcultural validity of SCT to the important developmental period of adolescence.