Thursday, May 12, 2011

Medical examiner may not be immune to bias

From the Durango Herald: "Should forensic scientists know as little or as much as possible about the facts of the underlying case?

An article from the University of California, Irvine, school of law addresses this question and presents the following anecdote:

An evolutionary biologist studying the lineage of the Australian finch utilizes DNA testing to determine whether more brightly colored males mate more and produce more young and whether the male in a bonded pair is always the father of his partner’s offspring.

The biologist is adamant that DNA test results must be examined blind (the scientist can’t know, for instance, which birds are a bonded pair when determining offspring lineage) because it’s human nature to seize upon evidence that supports the investigator’s hypothesis and minimize or discredit evidence to the contrary.

Because the danger of bias is well-known, a scientist using less rigorous procedures would never be able to obtain financial support or publish in peer-review journals, the biologist says.

“You must understand that this work is extremely important,” she said. “It affects our understanding of the entire evolutionary history of the finch!”

The interpretation of forensic evidence often has a major influence on the outcome of criminal prosecutions, so it’s extremely important, too, but rarely do forensic scientists interpret evidence blind.

They usually know the basic facts and nature of the case, and they understand how their determinations will influence the investigation and the likelihood of successful prosecution.

Decades of psychological studies have made it clear that contextual bias is a fundamental part of human decision-making rather than a moral failing, that people are unaware to a remarkable degree of the extent to which context influences them and that they are not able to eliminate these biases by rigorous training or force of will.

Most scientific disciplines take great care to eliminate contextual bias, and the argument that it poses no problem for criminalists working in labs is becoming less credible (especially since a 2010 report of the National Academy of Sciences on the forensic sciences).

Still, most people don’t admit that contextual bias might be a problem for medical examiners.

Are they not physicians? Should they not be privy to all information? Does anyone think doctors should focus only on physical examinations and be kept ignorant of context when making diagnoses? Of course not.

But there’s a basic difference between forensic and clinical medicine that people rarely consider: When a doctor is trying to figure out if a patient has heart trouble or indigestion, no moral considerations create bias by favoring one diagnosis over the other.

When a medical examiner is convinced by circumstantial evidence that some low-life has killed a child, it’s morally right to do everything possible to support the prosecution.

When she’s convinced by circumstantial evidence that an innocent man has been wrongfully accused or imprisoned, it’s morally right to do everything possible to exonerate him.

Are medical examiners able to reliably ignore these sorts of contextual biases when interpreting autopsy findings?

Don’t bet the farm ..."

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