Development and Validation of a Measure of Self-Efficacy to Resist Nonsuicidal Self-Injury

Research into nonsuicidal self-injury (NSSI) has primarily focussed on the experience and regulation of emotion. Recently, NSSI-specific cognitions, including self-efficacy to resist self-injury, have been explored to further understand the behaviour. However, within these studies self-efficacy to resist NSSI has been assessed broadly using an adapted measure of self-efficacy to avoid suicide. There is a need for a NSSI-specific measure of self-efficacy, which considers specific contexts that may influence confidence in the ability to resist self-injuring. This paper reports the development of such a measure. An initial item pool (125 items) was generated from interviews with people with lived experience of NSSI and experts in the field of self-injury. These items were then administered to 650 participants aged 18-40 years (M = 21.14, SD = 2.32, 45.69% with a history of NSSI). Analyses revealed a three-factor structure representing: contexts in which it would be difficult to resist NSSI (risk contexts); contexts which make it easier to resist NSSI (protective contexts); and contexts in which people are reminded of self-injury (reminders of NSSI). To reduce the number of items, eight items with the highest loadings on each factor were retained. The final 24 item (three subscales) scale fit the data well and demonstrated invariance across individuals with and without a history of self-injury. Correlations with related but distinct constructs (e.g., self-esteem, locus of control) supported convergent and discriminative validity. This measure could be used to further theoretical understanding of NSSI and may be useful in clinical settings.