Monday, August 13, 2007

A deadly numbers game

Today we are turning the blog over to Dale Wisely, a clinical psychologist and volunteer with our Alabama affiliate, Project Hope to Abolish the Death Penalty. Dale also is the father of former NCADP Jesuit Volunteer Sarah Wisely. He has written the following excellent essay:


Dale Wisely, Ph.D.

In the news recently we learned that John Couey, convicted for the horrific abduction and murder of Jessica Lunsford in Florida, has been deemed by the courts not to be mentally retarded and so is now eligible for the death penalty. If I understand the news reports, his IQ score was measured at 78. In Florida, mental retardation depends, among other criteria, on a score below 70.

In 2004, the Supreme Court ruled in Atkins v. Virginia, ending the execution of those with mental retardation. The Court held that the execution of the mentally retarded violates the Eighth Amendment ban on cruel and unusual punishment.

As an opponent of capital punishment I applauded this decision, reasoning that it would prevent some executions, even at the risk of making the practice of the death penalty more palatable to the general public, and slowing progress toward banning it entirely. But I immediately predicted that this ruling was going to cause the courts a lot of problems. There are fundamental problems with a system that is willing to spare the mentally retarded and execute the not-quite-retarded. Morality aside, there is a problem in the nature of measuring something as complex and vaguely defined as human intelligence.

Psychology, psychiatry, and education have no consensus about a specific definition of mental retardation. We have a consensus about a broad definition. A definition adopted in 2002 by the American Association on Mental Retardation (AAMR) summarizes this consensus.

Mental retardation is a disability characterized by significant limitations both in intellectual functioning and in adaptive behavior as expressed in conceptual, social, and practical adaptive skills. This disability originates before age 18.

Absent from this definition are specific IQ scores and scores on measures of what psychologists and educators call "adaptive behavior." Some states have attempted to establish a definition of mental retardation. Some more or less follow the AAMR definition. Others supply a cut-off score, most commonly 70. States which have non-specific definitions, or none at all, will presumably rely on a body of evidence, including expert opinion. This will be messy and courts will have to weigh conflicting evidence with the inevitable error when courts weigh conflicting evidence

Those states that establish more specific criteria, including IQ score cut-offs, will have difficulties as well, as apparently was the case in Florida.

Mental retardation is often identified when a person is given a standardized intelligence test, the score or scores fall below a cut-off score, and when the person also has substantial deficits in the way he or she actually functions in everyday life ("adaptive behavior"). IQ cannot, under any circumstances, be precisely measured. An IQ is an estimate and an estimate, by the way, of only a sampling of a person's cognitive abilities. (This is even more true of measures of adaptive behavior.) Because of the unavoidable "error of measurement" in IQ and adaptive behavior measures, these scores are always accompanied by a range of scores in which the person might well have scored. In other words, an IQ is always plus-or-minus a certain number of points.

Take this hypothetical: Two equally culpable codefendants are tried for capital murder in a state that establishes a cut-off IQ of 70. Putting aside adaptive behavior, one defendant has an IQ of 71. The other has an IQ of 69. Any psychologist or educator will tell you that there is no meaningful difference in those scores. None. This would be true of three points, four, six, or eight points difference. So, are we going to execute one of these defendants and spare the other?

If, as I think most reasonable people agree, it is wrong to execute persons with mental retardation then the only right thing to do, barring abolition of the death penalty entire, is to refrain from executing any person for whom there is any amount of credible evidence supporting a claim of mental retardation.


ike said...

It is sad that theoretically 2 points on an iq scale could determine whether one individual lives or dies. So arbitrary.

Read about Tennessee's abolition movement at:

glauber said...

Obviously, the system is retarded.

A Voice of Sanity said...

Surely there must be a better way to make these determinations than the dubious 'IQ test'? Or better still, move to LWOP and let decisions such as mental illness or mental incapacity decide where the prisoner is housed, not the measure of society's revenge upon that person.