Clinical biases in diagnosis


In the abnormal psychology option, what is the difference between cognitive biases and clinical biases?

Clinical biases are cognitive biases that take place when a psychiatrist or psychologist is trying to make a diagnosis and label the behaviour. They can arise from experience (‘these symptoms nearly always mean this mental health problem’) and result in a misdiagnosis when other explanations for the behaviour are too readily discarded. This is a confirmation bias – symptoms are interpreted to confirm the mental health professional’s original swift diagnosis. It was demonstrated in Rosenhan (1973)  when the admitting medical staff interpreted the very vague symptoms described as schizophrenia, and even more clearly when the normal behaviour exhibited by the pseudo-patients was interpreted by medical staff to confirm the validity of the original diagnosis.

They can also arise from an existing societal and/or personal bias, such as an ethnic or gender bias. Jenkins-Hall and Sacco (1991) found that a sample of USA psychotherapists showed an ethnic bias against black clients in that they evaluated depressed black clients more negatively than depressed white clients. While both groups were diagnosed with depression, the black clients (ethnic minority in this case) were seen as being less socially capable and were evaluated as more seriously depressed, using a standardised scale. A larger study by Bertakis et al (2001) demonstrated that women were much more likely than men to be diagnosed as depressed by their primary care physicians, even with a similar number of visits. This showed a gender bias in diagnosis.

So, there is a clear link between this material and the study of cognitive biases, especially confirmation bias.


Bertakis, K.D., Helms, J., Callahan, E.J., Rahman, A., Leigh, P. & Robbins, J.A. (2001).  Patient Gender Differences in the Diagnosis of Depression in Primary Care.  Journal of Women’s Health & Gender-Based Medicine, 10(7), pp. 689-698.

Jenkins-Hall , K. & Sacco , W.P. (1991).   Effect of Client Race and Depression on Evaluations by White Therapists.  Journal of Social and Clinical Psychology, 10(3), pp. 322-333.

Rosenhan, D. L. (1973). On being sane in insane places. Science179(4070), pp. 250-258.

Taking a holistic approach to the course

connections jigsawI have been trying over the past few years to do this, and am sometimes asked what I mean by ‘a holistic approach.’  The easy way is to demonstrate using an example. If you are teaching/studying the abnormal psychology option, for instance, you will probably be doing this after you have spent some time looking at the core approaches to explaining human behaviour (biological cognitive and sociocultural) and also looking at research methods and ethics.

So, now comes the time to apply your learning to the content of this option. Explore the differences between psychiatry (more medically and biologically based) and psychology (more cognitively and socially based). Take major depressive disorder, for example: how might a psychiatrist explain it?  How might they look for evidence to see if their explanation is correct and what sort of evidence would they see as valuable? How valid is their method of looking for evidence? How reliable is it? Does it allow them to develop a theory of etiology of MDD that has good explanatory power? How might they want to treat MDD once they are sure a person is suffering from it? Discuss the benefits and limitations of this treatment. Are there any ethical considerations regarding this treatment? 

Now, how might a cognitive psychologist explain MDD? How would s/he look for evidence and what would they accept as evidence? How valid is this method? How reliable is it? Does it allow them to develop a theory of etiology of MDD that has good explanatory power? How would a cognitive psychologist treat MDD.  Discuss the strengths and limitations of this treatment. Are there ethical considerations regarding this treatment?

What about sociocultural arguments that childhood trauma, domestic violence, poverty and stress can all singly or in combination be responsible for MDD? That removing the conditions that lead to MDD is the best treatment? 

Finally, consider the eclectic approach that is more common nowadays. What is the evidence that a combined approach to both the diagnosis, explanation of* and treatment for MDD may be more successful than a single approach? What is the evidence that doing nothing also works? What about a choice of approaches, or sequential treatment?

If we start the abnormal psychology option with these questions and work together to answer them, then the specific content becomes easier to understand in context of perspectives on abnormal psychology, and within the framework of approaches to research. This can be put into practice in the other options as well. Put it all together!

*e.g. Interaction between genetic vulnerability, environmental trigger and possible faulty cognition.