Emotion in non-suicidal self-injury: A contradiction between global self-reports and real-time responses
People who engage in non-suicidal self-injury (NSSI) report doing so largely to manage overwhelming emotions. Prominent theories of NSSI argue that an amplified emotional response system creates the context in which a person chooses to regulate their emotions by engaging in NSSI. In line with these theories, people who engage in NSSI consistently report greater global emotion reactivity and emotion dysregulation than do controls. These global self-reports of emotional functioning also predict the onset and cessation of NSSI, demonstrating their considerable utility in understanding the behaviour. However, global self-reports provide an overall evaluation of one’s average affective experience and so are ill-suited to isolating precise alterations in emotional responding.
I first establish how best to assess NSSI (Study 1a and 1b). I then leverage experimental affective science and individual differences methodologies to test whether NSSI is characterised by a more reactive and intense emotional response to challenge, and/or whether factors that help to create, modify, and later recall the emotional response are altered in those who engage in NSSI compared with controls. Study 2 compared how young adults with a past-year history of NSSI and controls subjectively and physiologically reacted to, and recovered from, acute stress. Study 3 compared how young adults with a past-year history of NSSI and controls subjectively reacted to both explicit and more ambiguous social exclusion.
Consistent with a wealth of research, across both Studies 2 and 3 people with a past-year history of NSSI reported considerably greater global emotion reactivity and emotion dysregulation than did controls. However, counter to predictions, both the NSSI and Control groups showed similar patterns of real-time emotional responding to both acute stress (Study 2) and social exclusion (Study 3), providing no evidence that NSSI is characterised by an amplified response to emotional challenge. In addition, we found no evidence that emotional recovery, emotion regulation strategy use, memory of emotional experience, or appraisal—all factors that shape the emotional response—operate differently in those who engage in NSSI. Focusing on how people make global self-reports, exploratory reanalysis of Study 2 and 3 suggests that people with no history of NSSI draw from their real-time experiences of acute (but not mild) emotional challenge when making judgements about their global emotion dysregulation. In contrast, people who engage in NSSI appear to rely on different channels of information when reporting their global emotion dysregulation.
Overall, this thesis demonstrates that, despite reporting considerably poorer global emotional functioning, people who engage in NSSI show largely typical responses to real-time emotional challenges. Given that global self-reports of emotional functioning appear to be critical for understanding NSSI onset and cessation, the discrepancy between global self-reports and measures of real-time responding highlights the complexity of the relationship between emotion and NSSI. To advance our understanding of emotional responding in NSSI, research should: a) establish the conditions (if any) under which people who engage in NSSI show amplified emotional responding, and b) isolate the psychological processes that underlie the experience of poorer global emotional functioning reported by people who engage in NSSI.