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Abnormal Psychology: Reliability and Validity of Diagnosis
Transcript of Abnormal Psychology: Reliability and Validity of Diagnosis
& Reliability of
Diagnosis Reliability of Diagnosis Validity of Diagnosis What does the validity of a diagnosis mean? Relevant Issues of the Validity of Diagnosis Relevant Studies Relevant Studies Relevant Studies What does the reliability of diagnosis mean? The Purpose of Diagnosis DSM-IV-TR Techniques of Diagnosis An Introduction to
Diagnosis To identify groups of similar sufferers so that psychiatrists and psychologists may develop explanations and methods to help those groups
Billing purposes for government Observation
Brain scans The Diagnostic and Statistical Manual of Mental Disorders (DSM) Will different diagnosticians using the same
classification system arrive at the same diagnosis? Beck (1962): Agreement between two psychiatrists on diagnosis for 153 patients was 54 %. This was due to vague criteria for diagnosis and different ways of psychiatrists to gather information
Cooper et. al. (1972): When shown the same video clips, New York psychiatrists are twice as likely to diagnose schizophrenia than London psychiatrists. London psychiatrists were twice as likely to diagnose mania or depression than New York psychiatrists Di Nardo (1993): Two clinicians separately diagnosed 267 people seeking treatment for anxiety and stress disorders. They found higher reliability for obsessive compulsive disorder but lower reliability for major depression
The reliability of earlier systems for diagnosis, e.g. DSM-II, was very poor, but it has been improved in revisions of the systems, e.g. DSM-IV-TR For a diagnosis to be valid, the diagnosis must identify a real pattern of symptoms and therefore apply appropriate treatment There is a tendency of practitioners of overemphasizing dispositional rather than situational causes of behavior when diagnosing patients (Fundamental attribution error)
The labeling of patients with certain disorders may affect the practitioners perceptions of them (compare with researcher bias), patients may act the label that has been given to them (self fulfilling prophecy). The label itself may simplify a problem that is highly complex
People may fake mental illness in order to avoid punishment (The insanity defense) Rosenhan (1973): 8 sane people could get admitted to mental hospitals merely by claiming to hear voices.
Rosenhan (1973): When a teaching hospital was told to expect pseudo-patients, they suspected 41 out of 193 genuine patients of being pseudo-patients. Defines a mental disorder as a clinically significant syndrome associated with distress, a loss of functioning, an increased risk of death/pain, or an important loss of freedom
DSM groups disorders into categories and then offers specific guidance to psychiatrists by listing symptoms required for a diagnosis to be given
Multi-axial approach where a diagnosing clinician considers the individual under investigation under 5 axis' The Five Axis' of DSM-IV-TR Axis 1: Clinical syndromes refers to the major diagnostic classification arrived by the clinician
Axis 2: Developmental and personality disorders consists of additional diagnostic classifications that may contribute to an understanding of the Axis 1 Syndrome
Axis 3: Medical conditions
Axis 4: Psychological stressors, all potentially stressful events or enduring circumstances that might be relevant to the disorder (rated on a scale of 1 [none] to 6 [catastrophic])
Axis 5: Global assessment of functioning, rates from highest level of social, occupational and psychological function on a scale of 1 (persistant danger) to 90 (good in all areas) currently and during the past year Relevant Studies Temerline (1970): Clinically trained psychiatrists were influenced in their diagnosis by hearing the opinion of a respected authority. Participants watched a video-taped interview of a healthy individual. The authority claimed he was actually psychotic (behavior is outside social norms, loss of touch with reality)
Chapman & Chapman (1967): Beginning clinicians observed draw-a-person test drawing randomly paired (unknowingly to participants) with symptom statements of patients. Although the relationship between symptoms and drawings were absent, participants rated a high associative strength between symptom and drawing characteristics (e.g. paranoia and drawing big eyes) Relevant Studies Lipton & Simon (1985): 131 patients were randomly chosen at a New York hospital. Initially there were 89 patients diagnosed with schizophrenia, eventually only 16. Initially, there were 15 diagnosed with depression, eventually there were 50. Evaluation Evaluation There is a large amount of research supporting the view that the reliability and validity of diagnosis are poor. This is due to many reasons, e.g. a possible social construction of mental illness, poor diagnostic tools, the possibility of faking, social influence, errors in attribution by practitioners and labeling
There are significant individual and cultural differences for the symptoms of mental disorders. An individual may have multiple mental disorders
A wrong diagnosis may lead to a social stigma (an ethical issue) Counter Arguments There are methodological problems with the studies on validity and reliability (researcher bias, generalization, ecological validity)
Revised diagnostic tools are higher in reliability than earlier versions, e.g. DSM-IV-TR
Many people do seek help voluntarily for disorders (which may mean that the disorder is valid)
The reliability of diagnosis is high for some disorders, e.g. obsessive compulsive disorder
There are many similarities of disorders across cultures
Diagnostic systems do not classify people, but the disorders that they have