Brief Lecture Notes for Unit 3
Problems associated with psychodiagnosis
We'll be spending most of this semester learning about specific psychodiagnostic categories, so it's useful at the outset to look at some of the reasons to be skeptical about the diagnostic enterprise:
1. The labeling effect: Once a person is given a label, others may interpret their behavior through the "lens" of the label. Through a process of social reinforcement and distorted perception, this may create a condition that did not really exist before, or (more likely) exascerbate a condition that was initially less dysfunctional. When a person "owns" a label as his or her own, a self-fulfilling prophecy effect is created that is equally problematic.
2. False dichotomies: Most psychological variables are continuous, not dichotomous, in nature. Yet, our language is dichotomous, so we tend to exaggerate the differences between social groups (sharpening) and to blur or minimize the differences within a single group (leveling). These perceptual distortions are inherent in the use of language. Any cutoff level between those who belong to one group and those who do not is usually an entirely arbitrary one.
3. The question of utility: Does diagnostic labeling really do any good, serve any useful purpose? If each form of mental illness requires its own unique, distinct, targeted form of treatment, then it might. But if the same general approach to counseling and therapy works with most or all forms of mental illness, then diagnosis may be at best a waste of time and resources. The notion of diagnosis is borrowed from the medical model, which presumes that mental illnesses have the same general properties as physical ones. But not all therapists share this view, which is an inherently reductionistic one.
4. The issue of reification: To reify means to treat something which is really just a verbal label or hypothetical construct as if it had a real, objective, independent existence. Put more simply, the problem is to think that labeling something explains it, when usually it does not. ("Why is he so shy? Because he is an introvert." If what we mean by the term "introvert" is "a person who is shy", then we have really explained nothing and are just arguing in a circle or tautologically: "He is shy because he is shy.") Diagnostic labels can masquerade as explanations when they are really nothing more than shorthand descriptions of specific behaviors or symptoms.
The moral? A healthy dose of skepticism and humility need to accompany our use of diagnostic labels. We're going to study them and make use of them, but keep the above issues in mind as we go through the course.
Two approaches to diagnosis
There are two general ways to classify anything... biological species, college classes, mental illnesses, or whatever else we might have in mind. Understanding the differences between the two is a key to understanding the challenge of psychological and psychiatric diagnosis.
1. The taxonomic approach is based on two assumptions. Think of how biologists classify living things into distinct species as a good example of the taxonomic approach:
a. Classifications are discrete in that every living thing belongs to one and only one species. No living thing belongs to more than one species (the categories are mutually exclusive or non-overlapping), and every living thing has a species (the categories are exhaustive or completely cover the territory). The categories are either/or in nature (no animal is partly one species and partly another).
b. The variables used to define species or to distinguish one species from another are domain-specific. That is, once we have made one broad classification ("Is this a plant or an animal?"), the questions we ask next depend on the previous classification. For instance, questions relevant to animals ("Is this creature warm-blooded?") make no sense when applied to plants, as plants are outside the range of convenience of the question.
2. The dimensional approach is based on opposite assumptions. Think of the "Big Five" model of normal personality (as summarized in Unit 1) as a good example of the dimensional approach:
a. Classifications are continuous (normally distributed variables). Middle-of-the road "types" exist (in fact, most of us are near the middle of any psychological variable), and there is no clear-cut, objective dividing line between one "type" and another.
b. The variables are universal or general, and independent or orthogonal. Each variable applies to all persons, and knowing where a person falls on one dimension tells us nothing about where they fall on another dimension.
The question is, which approach makes more sense when applied to abnormal psychology?
The current trend (as exemplified by the DSM-IV-R, to be discussed in Unit 4) within clinical psychology is to use the taxonomic approach, but that's mostly for reasons of convenience (or pragmatic utility). This shouldn't blind us to the fact that (a) syndromes are often overlapping and (b) the line between normal extremes and subclinical syndromes is often razor-thin. Personally, I prefer a dimensional approach, but right now I'm in a minority.
Study Guide
1. Discuss the following problems or difficulties related to the diagnostic enterprise: the labeling effect, false dichotomies, utility, reification.
2. How do taxonomic and dimensional approaches to classification differ? What assumption does each make? Which might be more apt for use in the process of clinical diagnosis, and why? What costs or problems might this involve?