By Emma Young

I hurt myself today

To see if I still feel

From Hurt by Nine Inch Nails

Deliberate self-injury (without the intent to commit suicide) is widely thought to be a way that some people, especially teenagers and young adults, cope with or express feelings that they find overwhelming. However, a set of three studies published as a preprint at PsyArXiv by psychologists at Swansea University, reveals that difficulties with perceiving and interpreting the bodily signals of emotion may also play a role – a finding that could help inspire new treatment approaches.

Previously, interviews with people who have self-harmed have included reports that they feel both “overwhelmed” by emotions they can’t identify, but also emotionally detached or “numb”. Hayley Young and her colleagues reasoned that if an individual is struggling to read their bodily signals of emotion properly (and “interoceptive ability” – the ability to sense physiological signals – is known to dip in adolescence), then self-injury may work to generate a stronger bodily input into their emotional experience.

The researchers ran three related studies using more than 300 young adult participants, mostly women. In the first few studies, the researchers looked for links between self-harm and self-reported factors, such as perceived difficulties in identifying and describing emotions. In the final study, interoceptive ability was measured using a standard method in which a person has to count their heartbeats over a period of time (without actually feeling for a pulse or using any other aid.)

Overall, the results revealed that participants with a history of self-harm were characterised by “a difficulty in distinguishing and interpreting interoceptive signals”. Participants who had self-harmed reported being more aware than others of general bodily sensations, but they tended to score worse on the interoceptive accuracy test.

“This is an important finding as low interoceptive awareness may be the biological basis for reports of ‘absent affect’ and ‘detachment’ and ‘disembodiement’” in those who self-harm, the researchers write. Low interoceptive accuracy may also contribute to self-harm, they suggest, in driving the individual to manipulate the way the body contributes to the experience of emotion.

A function of self-harm “may be to resolve a state of interoceptive and emotional uncertainty — [it] may serve to disambiguate the body’s role in emotional experience and provide clarity about what is being felt,” the researchers write.

The new findings add to past research that’s linked superior interoception to better emotional functioning, including experiencing more nuanced emotions. Conversely, poor interoception has been associated with a wide range of mental health problems, including depression and schizophrenia.

Young and her team added that their research suggests a pathway to new interventions: “a focus on improving compassionate self-focus may be beneficial.”

In fact, other groups are actively working on ways to improve people’s interoceptive accuracy. Sarah Garfinkel at the University of Sussex and her team are trialling just such a treatment for people with autism (poor interoception is relatively common in people with autism spectrum disorder). A pilot study on healthy people, which involved asking participants to count their heartbeats, and giving them feedback on how well they were doing, led to improvements in interoceptive accuracy and reductions in anxiety. This treatment research is ongoing. In theory, it might help with other conditions, too.

—Non-Suicidal Self-injury is associated with Multidimensional Deficits in Interoception: Evidence from Three Studies [this study is a preprint meaning that it has not yet been subject to peer review and the final published version may differ from the version upon which our report was based]

Emma Young (@EmmaELYoung) is Staff Writer at BPS Research Digest