Issues of Bias in Diagnosis
Diagnosis
• On your sheet explain how a psychologist
would be confident in saying an individual
has a particular mental illness.
• Mention the importance of a classification
system
Bias
• A bias means that certain people or
groups of people are more likely to be
classed as having a particular disorder
than other types of people.
The BIG question
• The issue is the cause of the bias:
• Does the bias come from the system being
used to make the diagnosis (so that some
groups tend to be misdiagnosed as having
an illness when they don’t)?
• Or is there is an actual difference in the
rates of mental illness between different
groups of people (in which case, the
diagnostic system is accurate)?
Cultural Bias in Diagnosis
• In Britain, certain cultural groups are more
frequently diagnosed with some disorders.
• Eg people of African descent are more
likely to be diagnosed with schizophrenia.
• Give TWO opposing explanations for this
fact
Explaining Cultural Differences
• While this evidence suggests that a bias in
diagnosis exists, it does not give us any
information about the nature of this bias.
• Is there a bias in the diagnosing, OR
• is there a genuine difference in the rates of
schizophrenia between those of African
descent, and others?
Explaining Cultural Differences
• Over-diagnosis due to inadequate
diagnostic methods
• Bias in the diagnostic tools (DSM IV and
ICD) which are Western
• Bias in the Psychological Tests
• Bias in the psychologist
Explaining Cultural Differences
• Genuine differences in rates of mental
illness.
• Stress of being a minority? - Littlewood
(1980)
• Unlikely - bias applies only to black people
Littlewood & Lipsedge (1989)
• Also, higher rates among 2nd generation
immigrants
Explaining Cultural Differences
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Genetic Differences?
African vulnerability to schizophrenia?
WHO – check findings p231
Littlewood(1989) Opposes – why?
Explaining Cultural Differences
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Type 1 or Type 2 error?
Type 1
Put healthy individuals in institutions
Type 2
Leave sick people out in the community
• Which is worse / more dangerous?
Explaining Cultural Differences
• Type 1 or Type 2 error?
• Malgady (1996)
• Denying cultural bias could lead to type 2
errors (not treating sick people)
• Trying to avoid Type 2 errors leads to
Type 1 errors (locking up healthy people)
• Malgady thinks this is preferable
• (Complicated - but try to grasp this)
Explaining Cultural Differences
• What does Vitamin D have to do with
cultural differences?
• Read the article – how does it explain the
aetiology of schizophrenia?
• Where does culture come in?
Gender Bias in Diagnosis