Wednesday, November 28, 2007

Flawed self-assessment

If there is one thing that all homebirth deaths have in common, it is overwhelming shock that something like that could happen to them. It's not that they didn't understand that a baby could die at homebirth; it's that it never entered their consciousness that THEIR baby could die at homebirth. Partly, this is because homebirth advocates are notoriously unrealistic about the chances of complications developing and the likelihood that serious complications can be managed at home. However, it also reflects a well known feature of human psychology, the inability to realistically assess one's own situation.

Dunning et al. in the article Flawed Self-Assessment Implications for Health, Education, and the Workplace, published in 2004 in Psychology in the Public Interest, explain this phenomenon. They are not writing specifically about homebirth, but their comments are particularly relevant:
... People overestimate themselves. They hold overinflated views of their expertise, skill, and character. That is, when one compares what people say about themselves against objective markers, or even against what might be possible, one finds that the claims people make about themselves are too good to be true. This bias toward undue optimism, self-aggrandizement, and overconfidence is exhibited in many ways.

Above-Average Effects
People, on average, tend to believe themselves to be above average - a view that violates the simple tenets of mathematics. In a survey of nearly one million high school seniors, 70% stated that they had "above average" leadership skills, but only 2% felt their leadership skills were "below average." On their ability to get along with others, almost all respondents rated themselves as at least average — with 60%rating themselves in the top 10% of this ability and 25% rating themselves in the top 1%. College students think they are more likely than their peers to live past 80 and have a good job; they think they are less likely to acquire a drinking problem or suffer a heart attack...

Overestimation of the Likelihood of Desirable Events
People overestimate their ability to bring about personally desirable events. Lawyers overestimate the likelihood that they will win the cases they are about to try. Stock pickers think the stocks they buy are more likely to end up winners than those of the average investor ...

Overconfidence in Judgment and Prediction
Finally, people place too much confidence in the insightfulness of their judgments, overestimating the chances that their decisions about the present are sound and that their predictions about the future will prove correct. This phenomenon is known as the overconfidence effect. College students overestimate the probability that their answers to general knowledge questions are correct. They are also overconfident in their forecasts of what events they will experience over the course of a semester ...
The reasons for this overconfidence effect are especially relevant to homebirth advocacy:
People lack crucial information they need when they compare themselves against others; they also ignore valuable information that they actually possess or could seek out. These twin themes are quite evident when one examines research on the above-average effect.We cite four informational deficits that lead people to believe they are doing much better than their peers. In addition, people neglect important information that could prompt them to reach more accurate conclusions...

The Double Curse of Incompetence.
People often do not have the knowledge and expertise necessary to assess their competence adequately. Consider, for example, the plight of the incompetent, who are often not in a position to recognize just how poor their decisions are. In many significant social and intellectual domains, the skills necessary to recognize competence are extremely close if not identical to those needed to produce competent responses. For example, recognizing whether an argument is logically sound requires a firm grasp of the rules of logic. If people do not understand the rules of logic, not only will they makelogical errors, but they will also not recognize that their arguments are logically defective — or that anyone else’s argument is logically superior. Thus, incompetent individuals suffer a double curse: Their deficits cause them to make errors and also prevent them from gaining insight into their errors...

Several studies have now shown that incompetent individuals (i.e., those performing poorly relative to their peers) fail to show much insight into just how deficient their performance is. College students scoring in the bottom 25% on a course exam walked out of the exam room thinking that they outperformed a majority of their peers...

Other work also demonstrates that poor performers, relative to their more competent peers, have more difficulty differentiating accurate from inaccurate performance. Compared with good students, poor students less successfully identify which specific questions they have gotten right on an exam and which they have gotten wrong. Novice bridge players are less likely than expert players to tell good moves from bad ones. Students with little experience in physics, compared with more accomplished physics students, have less accurate intuitions about which physics problems are generally difficult to solve. Paradoxically, although training people on logic improves their skill, such training also reveals to them past flaws in their logical reasoning, leading them to provide more pessimistic views of their logical reasoning ability at the moment their skill level rises.
Homebirth advocates suffer from this overconfidence effect. They believe that positive events are more likely than they are, and they believe that they are more capable of brining about desirable events than they really are. They are hampered by a lack of basic knowledge about science, statistics and childbirth. Paradoxically, it is this very lack of basic knowledge that makes it impossible for them to understand how little they know and how incorrect their assessments really are.

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