This is called nonsuicidal self-injury (NSSI), and it most commonly takes the form of cutting or burning the skin. Traditionally, many doctors, therapists, and family members have believed that people engage in NSSI primarily to manipulate others. However, recent research has found that such social factors only motivate a minority of cases and usually represent cries for help rather than coldhearted attempts to exploit caretakers. Although there are many reasons why people engage in this kind of self-injury, the most commonly reported reason is simple, if seemingly odd: to feel better. Several studies support the claim that self-inflicted pain can lead to feeling better. For example, Schmahl and colleagues scanned the brains of people with a history of NSSI during a painful experimental task designed to mimic NSSI. They found that the pain led to decreased activity in the areas of the brain associated with negative emotion. The reality of this effect provokes a perplexing question: How could self-inflicted pain possibly lead to feeling better?
One possible answer to this question is that some people are simply hard-wired to like pain. Although NSSI is associated with an increased pain threshold and tolerance, people who engage in NSSI still report feeling pain and, furthermore, report that this pain is unpleasant. Moreover, if these people are hard-wired to like pain, it is unclear why they primarily engage in NSSI when stressed or why they stick to moderate self-injury (e.g., cutting the skin) rather than severe self-injury (e.g., limb amputation).
Another possible answer is that these people want to punish themselves and that they simply like punishment. It is true that self-punishment is a commonly reported reason for engaging in NSSI; however, by definition, punishments increase negative emotion and make a behavior less likely to occur in the future. Thus, self-punishment may motivate some of these people, but self-punishment cannot be the reason that NSSI reduces bad feelings. During NSSI, something else must accompany the negative emotion associated with self-punishment and pain. Exciting new research now suggests that this "something else" is the relief that occurs when something that causes acute, intense pain is removed.
To illustrate this effect, imagine that one morning you visit the doctor for a routine check-up, and later that afternoon the doctor's office calls to inform you that you're in the advanced stages of cancer and have weeks to live.... Now imagine that the doctor's office calls back five minutes later and tells you that they mixed up your lab work with someone else's – you're actually in good health. You would not immediately go back to how you felt before the first phone call; rather, you would feel extreme relief, lasting for hours or even days. Note that it was not a reward (e.g., winning the lottery) that made you feel better, only the introduction and removal of something unpleasant.
New research suggests that the introduction and removal of physical pain may have a similar effect. Tanimoto and colleagues found that fruitflies avoided odors associated with the introduction of a shock, but approached odors associated with the removal of a shock. Similarly, Bresin and colleagues found that the removal various forms of experimental pain were associated with a reduction in negative emotion in people with no history of NSSI. This relief effect was particularly strong for people who had higher levels of negative emotion. This latter finding may help to explain why people with higher levels of negative emotion are more likely to engage in NSSI: they have more negative emotion to reduce, and thus more relief to gain. Using biological measures, Franklin and colleaguesobtained similar effects in both people with and without a history of NSSI. These new findings are especially interesting because it turns out that both general negative emotion and pain-induced negative emotion are processed in the same brain areas. This means that pain relief and emotional relief are essentially the same thing. Indeed, it was recently shown that pain relievers like acetaminophen also relieve emotional pain.
Many people find that it's hard to get emotional relief with traditional strategies (e.g., talking with friends). Consequently, they may resort to generating pain relief in order to generate emotional relief. Unfortunately, this also means that they have to generate acute, intense pain; that is, they have to engage in NSSI. Despite being an effective emotion relief strategy, NSSI is also a health-risk behavior that is associated with an increased risk of suicide. In short, NSSI can be a good thing for temporary emotional relief, but it's a bad thing for health.
The vast majority of people who engage in NSSI are not seeking to manipulate anyone and they're not wired differently than the rest of us. They simply tap into the natural emotional relief that accompanies the removal of intense, acute pain. They do this because they have trouble finding healthier ways to reduce their stress. Accordingly, ostracizing people who engage in NSSI only creates more stress and makes NSSI worse. The best way to help someone who engages in NSSI is to guide them to healthier ways to feel better.