自我伤害可以1使主体避免承受更大的痛苦 2modify their social environment 3 shift their attention away from unpleasant emotions or thoughts 4改变对自我的认知 5引发生理反应进而影响情绪

NSSI，非自杀性自我伤害
普遍程度（大家随便感受一下）
The most commonly cited figure fornonclinical adults is that 4% report having engaged inNSSI [14] . A more recent random-digit dialing procedureof adults (age: 19–92 years) across 48 US states found alifetime NSSI prevalence of 5.9%; 1.3% had engaged inNSSI on 10 or more occasions; 0.9% within the past 12months
一项在美国的调查显示，有5.9%的人一生中有过NSSI，0.9%的人最近一年内有NSSI的经历

以下是NSSI的始发年龄和终止年龄
Study participants consistently report that they first engagedin NSSI aged 12 through 14 years [16] . The medianage at onset in Klonsky’s [15] national survey was 14 years;the median age at offset was 20 years

相比于成年人，未成年人更多的报告自己有NSSI行为
In contrast to the rate reported among adults, the lifetime prevalence amongcommunity samples of North American adolescents hasbeen found to range from 13.0 to 23.2%, while the 12-monthprevalence has been found to range from 2.5 to 12.5%

辨析：emotion、mood、affect
emotion更短暂，mood更持久；affect最为宽泛，可以包括偏好和态度
An emotion anda mood can be differentiated by the length of time overwhich they take place: emotions are short, while moodscan last hours to days, or even weeks. Moods are more ofa ‘pervasive and sustained emotional “climate”’ [13] , andthey are not always tied to specific events [42] . In contrast,emotions have a quick onset and often last onlyminutes or even seconds [43] . Affect is the broadest andmost inclusive term for a valenced (i.e. positive or negative)state, covering moods and emotions as well as preferencesand attitudes

根据社会强化理论，NSSI可以改善自身处境
Spurring the peoplearound them to act in a more caring way can be a way ofmodifying the situation.
This theory is supported by thefinding that among young adolescent girls, peer victimizationwas related to the social-positive reinforcementfunctions of NSSI (‘to get attention’)

也有人指出NSSI可以减少自我负罪感
‘Self-punishment may be conceptualizedas an attempt to avoid shame or unwanted negativebeliefs about the self, as punishing the self may alleviatefeelings of guilt or shame.
具体实验可以参考
RMA Nelissen，Z Marcel
When guilt evokes self-punishment: evidence for the existence of a Dobby Effect.