This cross-sectional study examined how four temperament dimensions (Surgency, Negative Affectivity [NA], Affiliativeness [AF], Effortful Control [EC]) relate to loneliness in 885 Finnish Grade 9 adolescents (mean age 15.8, 56.4% girls), and whether psychological flexibility moderated those links.
High NA and high AF each independently predicted more loneliness; high EC predicted less loneliness; Surgency had no unique effect. Psychological flexibility buffered the loneliness risk from both NA (β = −.11, p < .001) and AF (β = −.17, p < .001): at high psychological flexibility, neither NA nor AF was associated with loneliness.
- Single-item loneliness measure limits nuance and precision. - Cross-sectional design prevents causal inference. - Non-clinical Finnish sample only; generalizability to other cultures, clinical groups, or educational systems is uncertain.
Adolescents with high negative emotionality or strong affiliative needs are at elevated loneliness risk, but building psychological flexibility skills (e.g., via ACT-based programs) may offset that risk. Clinicians working with temperamentally vulnerable teens could consider ACT-informed approaches targeting experiential avoidance and cognitive fusion.
