The Real-Time Interplay Between Identity, Emptiness, and Nonsuicidal Self-Injury Ideation: An Ecological Momentary Assessment Study in Treatment-Seeking Individuals

Although research has shown that individuals with identity difficulties are at greater risk of nonsuicidal self-injury (NSSI), less is known about the associations between identity, emptiness, and NSSI ideation in daily life. This study addressed this gap using an ecological momentary assessment design with six daily EMA surveys for 28 days in a treatment-seeking sample of 123 adolescents and adults (mean age = 23.07, SD = 5.32), yielding a total of 14,776 longitudinal assessments (median compliance = 77.4%). Results showed that lower-than-usual momentary identity synthesis and higher-than-usual momentary identity confusion independently predicted within-person changes in the intensity of NSSI ideation. Even after controlling for negative affect, we found evidence for a cyclic identity-emptiness model in which identity and emptiness bidirectionally increase each other's intensity on a 2-hr time scale and subsequently predict higher intensity of NSSI ideation 2 hr later. Analyses comparing full- and half-longitudinal mediation models consistently confirmed the robustness of these findings for identity synthesis. The strength of these within-person associations was not moderated by the number of baseline borderline personality disorder symptoms, except for a higher within-person mean of emptiness. These findings highlight the potential value of ecological momentary interventions that target identity and feelings of emptiness in real time to prevent NSSI ideation among patients. Future research should further clarify the dynamic interplay between identity and emptiness in daily life and how these processes contribute to the emergence and maintenance of NSSI.