The New Laws of Psychology by Kinderman Peter

The New Laws of Psychology by Kinderman Peter

Author:Kinderman, Peter
Language: eng
Format: epub
ISBN: 9781780336015
Publisher: Constable & Robinson


RELIABILITY AND VALIDITY OF DIAGNOSES – VALIDITY

As well as being reliable, diagnostic classifications should also be valid – scientifically meaningful and representing real ‘things’. Clearly, reliability and validity are closely related: if a diagnosis cannot be agreed upon, or if the same person is given different diagnoses at different times or by different doctors, all the different possible alternatives cannot all be ‘real’.

In order to examine these principles more clearly, let us consider an imaginary ‘illness’ – Kinderman’s Syndrome, which is diagnosed by the following ‘symptoms’: thinning brown hair, a south-east English accent and protruding ears. This diagnosis could be quite reliable because a particular person (let’s call him Peter) is likely to be assessed as meeting the diagnostic criteria for Kinderman’s Syndrome each time he is interviewed (he is unlikely to change his hair colour and the size of his ears). Two different raters are likely to agree on the presence or absence of the ‘symptoms’ and, if there is any doubt, very strict criteria could be agreed, specifying exactly what a ‘south-east English accent’ or ‘protruding ears’ meant. We could even define the exact shade of ‘brown’ we meant (which could be very useful as the candidate gets older and greyer). The reliability of the ‘syndrome’ could be of a satisfactory level – we could easily compare people against the criteria and we’d agree on whether the criteria are met.

However, is this valid? Is there in any real sense a syndrome identified by these criteria? The idea that there might be a syndrome – ‘Kinderman’s syndrome’ – can’t be justified merely because we can first list a set of criteria and then reliably agree on whether they are present or not. Obviously, there is no real or valid illness called Kinderman’s Syndrome, and the fact that we can invent it and then even diagnose it reliably does not make it valid.

It is entirely possible to invent invalid diagnoses. We have done it before. Although it’s fair to say that the diagnosis never really took hold in psychiatrists’ imaginations. The nineteenth-century American doctor Samuel Cartwright seriously proposed the diagnosis of ‘drapetomania’,11 which was a quasi-medical explanation for the supposedly inexplicable tendency of slaves to attempt to escape from their captors. According to Cartwright, their desire for freedom was a symptom of a mental illness, drapetomania (the Greek word drapetes means a runaway slave). In a paper entitled ‘Diseases and peculiarities of the negro race’, Cartwright suggested that drapetomania was the result of people either treating their slaves as equals or, alternatively, with cruelty. He argued that the Bible said that slaves must be submissive to their masters and so it was madness to wish to run away. Cartwright further argued for preventative measures – if slaves were showing signs of being unhappy, Cartwright prescribed ‘whipping the devil out of them’ as a ‘preventative measure’. Clearly this is an invalid diagnosis – there is no such ‘illness’ as drapetomania. So how valid are other psychiatric diagnoses: have we made up other invalid concepts? Some easy targets present themselves immediately.



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