September 18th, 2013
Lecture 1 - Defining Abnormal Behaviour
•Psychopathology is the study of the illness of the mind and behaviour.
•Abnormal behaviour is easy to see but hard to define. "Strange behaviour" is insufficient
to be labelled abnormal.
•DSM4 stated that a learning disability is a deviation in the norm for language or
mathematical probability. The goal for DSM5 (version currently being used) is to make
the definition of abnormal behaviour more statistical.
•Abnormal behaviour is the behaviour that most people are not displaying; it deviates
from the norm. Therefore, normal behaviour is behaviour that most people display.
•Abnormal thoughts, feelings and actions are behaviours.
•Ideally psychologists would like to define abnormality as a statistical deviation. But this
proves difficult because it's hard to collect data about everyday things such as 'what's the
normal amount of times a person blows their nose in a day?' The problem with this
definition is that it disregards deviant behaviours which are not favorable. For example, a
score of 100 if the average IQ. But is your intelligence abnormal if you're 1SD below the
average (75?) or 1SD above the average (125)? Do these people need help?
•Abnormal behaviour is known as psychopathological behaviour.
•DSM5 states that substance abuse is not normal because it's addictive.
•Cultural Norms: What might be normal in one society, situation or environment may not
be normal in another. There are some types of behaviours that are distinctive and
abnormal in most cultures (such as hallucinations and delusions which people with
schizophrenia experience). There are many behaviours which are situationally defined;
(for example getting naked in a public arena is abnormal but not in a public locker room).
•Developmental Norms: At certain ages you're expected to develop certain behaviours.
For example hitting your sister at age 7 vs. age 30 has different consequences. The
September 18th, 2013
greater the deviation from the norm, the higher the concern. For example most kids learn
telegraphic speech by the age of 2, and if not, it's a concern by age 3 and a bigger concern
by age 4, etc. Milestones are averages of faster (positive) or slower (negative)
development, but they all have the same outcome.
•Frequency, Intensity and Duration: For example: depression is a mood disorder most
commonly caused from losing someone. It significantly needs to interfere with the
normal behaviour to be considered abnormal. For example, being sad for a while vs.
harming yourself after losing your dog.
•Etiology Models of Abnormal Behaviour
•A) Medical-Disease Models
•Genetic Models: Genes act as a primary determinant of behaviour. For example
depression has many genetic markers. There are multiple genes involved and even if you
inherit the gene, it doesn't mean you'll develop that certain pathology. (For example
schizophrenia: looked at twin studies and their concordance rates. If one twin developed
schizophrenia, there's a 50% chance of the other twin developing it. The other 50% is
impacted by the environment - i.e. stress). Easily treated with pharmacological therapy.
•Biochemical Models: Genes determine the chemistry in our bodies. There can be
insufficient or too much chemistry in your brain, causing a disbalance. For example in
schizophrenia there is a chemical disbalance of too much dopamine, and in depression
there's not enough serotonin, dopamine and norepinephrine.
•Neurophysiological Models: Abnormal behaviour resides in the brain. Dysfunction of
the brain can be either genetically inherited, congenital (through time of birth), or
acquired through brain damage. For example in ADHD, the prefrontal cortex does not
•Psychoanalytic Model: Causes of abnormal behaviour come from external forces.
•B) Environmental Models
•Socio-Cultural Models: Social and cultural determinants are expressed when there's
social or psychological stress (which is the most determinant factor). We study family,