Thursday, April 27, 2006

Criminal justice and the Rosenhan Experiment

In his famous experiment, David Rosenhan raised serious questions about the validity of psychiatric diagnosis. Sane people were admitted into psychiatric hospitals because they claimed that they heard voices saying "empty", "hollow" and "thud". Once admitted they no longer claimed to hear voices and behaved normally. Moreover, they made no attempt to falsify their family history or other relevant biographical details in order to appear unstable. Nonetheless, these pseudopatients were admitted and diagnosed as mentally ill. In no case were they caught as imposters-not even when their symptoms quickly disappeared.

Rosenhan made a couple of telling observations in his 1973 paper in Science ("On Being Sane in Insane Places").

Once a person is designated abnormal, all of his other behaviors and characteristics are colored by that label. Indeed, that label is so powerful that many of the pseudopatients' normal behaviors were overlooked entirely or profoundly misinterpreted. Some examples may clarify this issue.

As far as I can determine, diagnoses were in no way affected by the relative health of the circumstances of a pseudopatient's life. Rather, the reverse occurred: the perception of his circumstances was shaped entirely by the diagnosis.
The medical professionals were primed to see abnormality. Once they thought they saw it, that perception distorted every thing they learned about the patient.

It seems to me that something similar can happen when a genuinely innocent person is caught in the criminal justice system. The police, the prosecutors, and (maybe) even the defense attorneys are accustomed to dealing with guilty people. There is a temptation to shape any and all evidence into a mosaic that proves guilt. Was the subject nervous at the interview? Evidence of a guilty conscience. Was he calm? The brazen act of a born manipulator. Did he hire a lawyer? Only the guilty lawyer-up. Did he come in with no attorney? The bold gambit of a practiced liar.

If the suspect offers exculpatory evidence the prosecutors can simply revise their theory of the crime. Does she have an alibi for 5.00 PM? Well, then, the crime must have occurred earlier.

There seems to be no inherent dynamic in the investigation to find the best "explanatory fit". Rather it appears that once an explanation is chosen, nearly all the effort goes to defending it. Since the fallacy of the ad hoc hypothesis is encouraged ("on-going investigation") the prevailing prosecution theory is almost impossible to falsify.*

It goes without saying that these problems are magnified when the investigation becomes fodder for the MSM. The fundamental weakness in the system becomes evidence of things as yet unseen. The obstinate reliance on the initial diagnosis is taken as proof that investigators know more than they are saying. When public information raises questions about the state's case, crime pundits will rush forward to assure us that the prosecutor must have evidence that he is holding back.

As someone with an unbecoming interest in epistemology, historiography, and methodology this bothers me. As a conservative, it also bothers me that my fellow right-wingers only get riled up on these issues when they can use them to attack their traditional enemies-Al Sharpton, feminists, campus leftists-- as in the Duke lacrosse case.

*UPDATE and clarification. What i was trying to say was this: Once a suspect is picked, the investigation slips from "who did it?" to "how did X do it?". Further, the process does not easily return to the first question even when new evidence appears.

No comments: