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Understanding Self Mutilative Behavior

 Jill Flemming High

 Penn State College of Medicine

 March 2005

  1. Self Mutilative Behavior (SMB)  definition: -Deliberate damage to one’s own body tissue without suicidal intent

-Part of the larger class of self-injurious behavior that includes actions ranging from stereotypic skin-rubbing to completed suicide


  1. Epidemiology: Adults – 4% of general population, 21% or psychiatric inpatients

Adolescents – 14%-39% in community, 40%-61% of psychiatric inpatients


  • The high rate of SMB in adolescents reveals the need for better understanding of how to effectively assess and treat SMB


  • First need to understand nature of problem by identifying risk factors, associations, methods, frequencies, and how they relate to behavioral functions and theories.


  • Two experiments by Nock and Prinstein in 2004 and 2005 illustrate a functional approach to assessment of SMB and contextual features and behavioral functions of SMB among adolescents.
  • Both assess SMB in 89 adolescent psychiatric inpatients referred for self-injurious thoughts or


  1. 2004 Study by Nock and Prinstein
  2. Hypothesis of authors: There are four primary functions of SMB
  3. Automatic-Negative Reinforcement: to achieve a reduction in tension or other negative affective state – “to stop bad feelings”
  4. Automatic-Positive Reinforcement: to create a desirable physiological state – “to feel something, even if is was pain”
  5. Social-Negative Reinforcement: to escape from interpersonal task demands – “to avoid punishment from others”, “to avoid doing something unpleasant”
  6. Social-Positive Reinforcement: to gain attention from others or to gain access to materials – “to try to get a reaction out of someone even if it is negative”, “to let others know how unhappy I am”
  7. Goal of study: to examine reasons adolescents engage in SMB and test whether those reasons can be classified in above four categories
  8. Methods: self report measures – comprehensive intake evaluations and a supplemental clinical evaluation
  9. Functional Assessment of Self Mutilation – measures methods, frequency, and functions of SMB
  10. 11 methods of SMB
  11. Cutting/Carving Skin
  12. Picking at a wound
  13. Hitting self
  14. Scraping skin to draw blood
  15. Biting self
  16. Picking skin to draw blood
  17. Inserting objects under skin
  18. Tattooing self
  19. Burning skin
  20. Pulling out own hair
  21. Erasing skin to draw blood
  22. Cutting/carving skin, picking at a wound, hitting self, and scraping skin were most prevalent of the 11 methods
  23. Mean number of incidents in past year per adolescent was 80
  24. Most began SMB in early adolescence, although some began in childhood (mean age of onset was 12.8 years)
  25. No significant gender difference for presence of SMB
  26. Self-reported reasons for engaging in SMB (each fall under one of the four behavior models discussed above)
  27. In a list of 22 reasons for engaging in SMB, the following 6 were most frequently ranked reasons
  28. To stop bad feelings – 52.9% (automatic reinforcer)
  29. To feel something even if it was pain – 34.1% (automatic reinforcer)
  30. To punish yourself – 31.8% automatic reinforcer)
  31. To relieve feeling numb or empty – 30.6% (automatic reinforcer)
  32. To feel relaxed – 23.5% (automatic reinforcer)
  33. To give yourself something to do when alone – 23.5% (social reinforcer)
  34. Reasons related to automatic reinforcement were endorsed more frequently
  35. Suggests that primary purpose of most adolescent SMB is regulation (positive or negative) of emotional or physiological experiences
  36. Helps indicate what interventions would be most efficacious at decreasing these behaviors according to what the identified function of that patient’s SMB is: the intervention would be most effective if aimed at replacing the SMB with a functionally equivalent behavior
  37. If automatic – focus therapy on enhancing alternative affect regulation skills
  38. If social – focus on teaching more adaptive interpersonal communication skills


  1. 2005 Study by Nock and Prinstein
  2. Used same population of 89 adolescent psychiatric inpatients
  3. 1st goal: to extend the 2004 study’s “four functional model” by examining some of the contextual features that precede SMB (behavioral antecedents) as well as factors which serve to punish SMB
  4. Contextual Features
  5. Impulsiveness of SMB
  6. Use of alcohol or drugs prior to SMB
  7. Role of social modeling in initiation of SMB
  8. Absence of physical pain experienced as a result of SMB


  • Each factor assessed by self report on tested surveys


  1. Results of Contextual Features portion of study
  2. Impulsiveness – most self mutilators contemplated SMB for a few minutes before performing each incident
  3. Use of alcohol – most reported not using alcohol or drugs during incidents of SMB
  4. Pain – most reported experiencing little or no pain during incident
  5. Social – 82% reported SMB among at least one of their friends in previous 12 months – suggests social modeling may play a role
  1. Interesting associations made from these results
  2. Endorsement of a social function of SMB was significantly associated with amount of time spent contemplating
  3. Endorsement of a social positive reinforcer was significantly associated with the number of SMB incidents performed by one’s friends
  4. Endorsement of SMB for positive reinforcement (automatic or social) was significantly associated with absence of alcohol or drug use during SMB
  5. Experience of more physical pain during SMB was significantly associated with the amount of time spent contemplating incidents and the number of incidents performed by friends


  1. 2nd goal:  to explain relations between SMB and some clinical correlates which other
  • authors have identified in previous studies
  1. Hopelessness and previous suicide attempts (hypothesized automatic negative reinforcer and not automatic positive reinforcer)
  2. MDD and PTSD (hypothesized automatic positive reinforcer)
  3. Loneliness and socially prescribed perfectionism (not internal perfectionism) (hypothesized social positive and social negative reinforcers)


  • Each factor was then assessed by separate, previously tested rating scales of loneliness, hopelessness, perfectionism, depression, etc.


  1. Results of Relations portion of study
  2. Recent suicide attempts and hopelessness significantly associated with only automatic negative reinforcement
  3. Depressive and PTSD symptoms significantly associated with automatic positive reinforcement
  4. Socially prescribed perfectionism significantly related to social positive and social negative reinforcement
  5. Depressive symptoms also significantly associated with social positive and social negative reinforcement
  6. Loneliness was not significantly associated with any of the four functions


  2. SMB typically is performed impulsively, without alcohol or drugs, and in absence of physical pain
  3. The impulsiveness suggests that the performance of SMB is influenced by immediate internal and external contingencies rather than the result of long term decision making process and planning
  4. Lack of physical pain is of high concern because it suggests SMB is difficult to prevent and treat.



  1. 2002 Gratz Study – identifies childhood risk factors for SMB among college students
  2. Method was again assessments through surveys
  3. Results:
  4. In Women: the following were significant risk factors for SMB
  5. sexual abuse
  6. dissociation
  7. paternal insecure attachment
  8. maternal emotional neglect
  9. paternal emotional neglect


  1. In Men: the following were significant risk factors for SMB
  2. dissociation
  3. childhood separation


  1. Conclusions:
  2. Highlights the importance of care-giving relationship in the etiology of self- harm
  3. Highlights the SMB among men contrary to general perception that this behavior it is common only in women




  1. Burns et al. Clinical management of deliberate self-harm in young people: the need for evidence-based approaches to reduce repetition. Australian and New Zealand Journal of Psychiatry 2005; 39: 121-128.
  2. Gratz et al. Risk factors for deliberate self-harm among college students. American Journal of Orthopsychiatry 2002; 72: 128-140.
  3. Nock and Prinstein. A functional approach to the assessment of self-mutilative behavior. Journal of Consulting and Clinical Psychology 2004; 72: 885-890.
  4. Nock and Prinstein. Contextual features and behavioral functions of self-mutilation among adolescents. Journal of Abnormal Psychology 2005; 114: 140-146.
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