Nonsuicidal self-injury (NSSI) is defined as direct, deliberate bodily harm without suicidal intention. Recent studies indicate that prevalence rates are increasing worldwide, in particular under adolescents, indicating a growing public health issue. An impaired ability to regulate negative emotion has been suggested to play a potential role in NSSI behavior. Some recent interventions aim at improving dysfunctional emotion regulation via 'acceptance'. Acceptance represents an objective, nonreactive, nonjudgmental, and calming emotion regulation strategy, partly based on the philosophy of dialectical behavior therapy (DBT) that has been widely used in the clinical treatment of NSSI behaviors. The aim of the present functional magnetic resonance imaging (fMRI) study is to examine whether adolescents with NSSI can implement the acceptance strategy in naturalistic emotional contexts (immersive video clips) and whether they differ from healthy controls in terms of behavioral and neural effects. To this end, the investigators recruit one group of NSSI adolescents (n=40) and one healthy control group (n=40), to compare the subjective emotional experience as well as underlying neural activity as measured by blood oxygenation level-dependent (BOLD) fMRI. The investigators hypothesize that compared to HC, NSSI adolescents will experience stronger negative emotions and show dysregulated neural recruitment of brain systems engaged in emotional reactivity and regulations (e.g. limbic regions, default mode network, and frontal regions).

Inclusion Criteria:

• 15-18 years
• right-handed
• normal or corrected normal visual acuity
• meet the proposed DSM-5 frequency criteria (e.g., ≥5 days of NSSI behaviors in the past year)

Exclusion Criteria:

• diagnosis of borderline personality disorder, major depressive disorder, other psychiatric disorders, etc.
• high suicidal risk
• recent use of medications that can affect neural activity
• have received or are receiving Dialectical Behavior Therapy (DBT) other treatment for emotional problems within the past 6 months
• have a contraindication to MRI scanning (e.g., metal implants, claustrophobia or other conditions that make them inappropriate for MRI scanning)

Treatment-seeking NSSI individuals will be recruited from local hospitals and HC from the community.