Some Problems with DSM-IV-TR Classification
- emphasizes biological factors, which in turn means that potential environmental and
cognitive determinants may be overlooked
- reliability: it can be inconsistent across applications; psychological disorders don’t have
- validity:: experiment done where a group of associates pretended to have psychological
disorders and were admitted into mental institutions for up to 3 weeks
- false positive outcomes of medical tests; e.g. natural bereavement may be mistaken for
major depressive disorder
DSM-V recommends categorization moves away from the medical model of disorder to
embrace the dimensional approach to personality.
Labelling someone with a disorder can affect clinical judgements...
Diagnosing a psychological disorder only describes the symptoms of the disorder, not the
underlying causes and psychological processes.
The Need for Classification
Even though labelling people as mentally ill sometimes stops people from taking personal
steps towards improvement, it can be advantageous.
We must be able to classify specific disorders reliably and accurately in order to be able to
Prevalence of Psychological Disorders
- Roughly 11% of Canadians suffer from a psychological disorder or substance-abuse
- Substance use disorders, mood disorders, and anxiety disorders are the most common.
Clinical versus Actuarial Diagnosis
clinical judgements: Diagnoses of psychological disorders or predictions of future
behaviour based largely on experts’ experience and knowledge.
actuarial judgements: Diagnoses of psychological disorders or predictions of future
behaviour based on numerical formulas derived from analyses of prior outcomes.
- Actuarial judgements are superior; their reliability is higher. (They always produce the
same judgement for a particular set of data...13% increase in accuracy when actuarial
methods are used!