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Child Neuropsychology A blog by Dr Jonathan Reed
  • Why do people commit murder?

    Everyone is a psychologist.  By that I mean that everyone tries to work out why people behave the way they do.  This is an inbuilt social drive that helps us to interact normally.  It is based on theory of mind which is about understanding other people’s mental states and intentions.  Lack of theory of mind is the key disability in Autism.   In my work I find that most people have a strong belief about why someone is behaving the way that they do (although in my work I think that it is often a wrong belief).

    I think we base our understanding on why others behave  the way that they do on what we think about ourselves and our cultural norms.  This is essential to group cohesion.  No one can truly know how another person is thinking but we automatically make an educated guess.  The difficulty comes when normal behaviour breaks down.   We know that in some individuals behaviour and personality changes dramatically with acquired frontal brain injury- see the case of Phineas Gage.   I see similar difficulties in my work with children with head injury, neurodevelopmental disorders and sometimes those with a history of abuse and neglect.  With these children I see very challenging behaviour that doesn’t respond to normal parenting or behaviour modification.  I will write about why this is in more detail at a later date (to with difficulties in development of frontal brain areas). In general though behavioural control is more complicated than it seems.

    I was particularly struck by this difficulty in understanding why some people behave the way they do when reading a research paper looking at the most extreme of behaviours, murder.  Why does someone comit murder?  The paper looks at 77 inmates or defendants charged with murder in the US and referred for neuropsychological assessment.  The sample is self selected because they were referred for clinical assessment rather than randomly chosen for research.  However, the sample characteristics are striking.  Some of the key facts are:

    • 49.4% had a developmental disorder in childhood.  (36.4% had ADHD)
    • 87% had a brain injury (self reported and 10% had documented evidence)
    • 85% had a history of substance abuse.
    • 45% had a psychiatric history
    • 35% had a history of abuse in childhood.

    From the neuropsychological assessment the mean IQ was 84 , which is a standard deviation below the norm.  Mean working memory was 87 which is low average.  The mean logical memory score was 68 which is very low indicating significant memory problems.  The sample also had a high rate of assessed executive function difficulty (executive function is the cognitive ability associated with the front area of the brain).

    You will need to read the paper to find all the details because there are so many interesting factors in the sample.   However, taken together the majority of the sample had some form of brain damage/ disorder or abuse stemming from childhood (which as I have discussed here often leads to developmental brain damage).   Exactly what is going on in their heads can never be know and the neuropsychological factors don’t explain the trigger or situation in which the murder took place.  However, it is clear that there are neurological and neurodevelopmental factors going on here, and given what we know about these in childhood and from case studies, it is unclear how much control such individuals have in a given situation.  I don’t offer this as an excuse to let people off and certainly I think many of these people are extremely dangerous.  But the results may shake our assumptions  (based on our own theory of mind) as to why people behave the way that they do.  Consider this next time you hear about a murder in the News.  Also the results may point to the importance of prevention in terms of early identification and treatment of childhood neurological problems and childhood abuse.  So many of these people’s problems seem to stem from experiences and events in their childhoods.

    4 Comments

4 Responses to “Why do people commit murder?”

  1. martin pederson said on

    I work in chemical dependancy and the common demonator is they don’t know how to let go of issues. Thats what drives people to abuse themseleves and or others.

  2. martin pederson said on

    I enjoy listening to bands like tool and metallica. Metallica’s song, “Sanitarium,” describes what happens to people if they don’t know how to let go. They go crazy. Tool’s song 46×2 is another good one. The shadow is a person’s thought.

  3. I really wonder why you called this particular article, “Dr Jonathan Reed
    - Child Neuropsychology Blog Archive Why do
    people commit murder?”. Anyway I actually enjoyed the post!
    Thanks for your time-Grant

  4. ashuli caca said on

    i never even liked this website i just needed it for my reasearch paper

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