Table 1.

The functional models and etiological models of NSSI.

Model	Authors	The Core of the Model
Functional models
1. The four-function model (2004)36	Nock and Prinstein	The 4 primary functions of NSSI include 2 dimensions: automatic regulation versus social regulation, and positive reinforcement versus negative reinforcement
2. Seven function models (2007)12	Klonsky	Seven functions include affect regulation, antidissociation, antisuicide, interpersonal boundaries, interpersonal-influence, self-punishment, and sensation-seeking
Etiological models
1. The developmental psychopathology model (2004)47	Yates	NSSI is a compensation strategy for relational adaptation and regulatory adaptation based on trauma-induced adaptive functional defects
2. The experiential avoidance model (2006)48	Chapman et al	NSSI is primarily maintained by negative reinforcement in the form of escape from, or avoidance of, unwanted emotional experiences
3. The emotional cascade model (2008)49	Selby et al	High levels of rumination may cause extremely intense states of negative affect, which result in dysregulated behaviors (NSSI) that can distract from rumination, and thus reduce that state of negative affect
4. The cognitive-emotional model (2017)50	Hasking et al	The model is based on (1) the process model of emotion regulation, (2) the model of difficulties in emotion regulation, (3) the experiential avoidance model, and (4) the emotional cascade model. Factors will increase the risk of NSSI including (1) a propensity towards emotional reactivity, (2) negative self-schemas, (3) outcome expectancies which hold that performing NSSI will achieve a desired mental state, (4) a belief in the ability to self-injure, or limited belief in the ability to resist NSSI, and (5) poor emotion regulation strategies
5. The benefits and barriers model (2018)51	Hooley and Franklin	NSSI carries many powerful benefits including (1) self-punishment benefit, (2) affective benefit, (3) communication benefit, and (4) affiliation benefit. Most people do not access these benefits because there are several barriers that motivate them to avoid self-injury including (1) awareness barrier, (2) aversion barrier, (3) pain barrier, (4) positive self-barrier, and (5) social norms barrier
6. The integrated theoretical model (2009)35	Nock	NSSI can serve several intrapersonal and interpersonal functions. The risk of NSSI is increased by general factors that contribute to problems with affect regulation or interpersonal communication and by specific factors that influence the decision to use NSSI rather than other behavior to serve these functions
7. The integrated motivational-volitional model (2012)52,53	Connor et al	The model is based on (1) the arrested flight model, (2) the diathesis-stress hypothesis, and (3) a dominant model of health behavior. NSSI develops through three phases: the premotivational phase, the motivational phase, and the volitional phase. The occurrence of NSSI depends on motivational moderators and volitional moderators, including a range of factors
8. The behavioral-functional analysis model (2020)54	Minlu Liang et al	The possible causes, susceptibility, process, and maintenance factors are important parts of the development and progression of NSSI

NSSI indicates nonsuicidal self-injury.