As staunch defenders of the much-maligned concept of the intelligence quotient, these scientists found vindication in the Supreme Court's embrace of intelligence testing, though they cautioned that the Justices' understanding of the complex subject was simplistic.
The IQ experts were particularly amused that newspapers that routinely condemn IQ tests as biased and meaningless were quick to endorse intelligence exams in this case. The New York Times, for example, editorialized, "[I]nflicting the death penalty on individuals with I.Q. scores of less than 70 who have little understanding of their moral culpability violates civilized standards of justice."
Linda S. Gottfredson, co-director of the University of Delaware-Johns Hopkins Project for the Study of Intelligence and Society, said, "Just about the only time I see journalists and liberals take IQ seriously is when it meets their ideological predilections. For example, they treat IQ as real when anyone claims that early intervention raises it, but not when evidence goes the other way. And so it is with crime. We are told we must not link IQ with crime, unless low IQ can be used to roll back the death penalty."
Another staunch backer of the much-maligned IQ test, evolutionary biologist Gregory Cochran, an adjunct professor at the University of Utah, collects examples of how the New York Times consistently refuses to mention IQ in its coverage of student performance and other topics where IQ would appear to be highly relevant. In response to the Times' editorial, he laughed, "This shows that the typical New York Times aficionado can be for something one day and support its opposite the next, without a twinge."
The Court left it up to the states to determine what should be the cutoff score for mental retardation. The 18 states that had already banned executions of the retarded tend to use an IQ of 70 (or occasionally 65 or 75) as the dividing line, often combined with other evidence of functional impairment.
To prevent killers from trying to cheat death by intentionally scoring poorly on his IQ test, most of these states require evidence that they were already retarded by the age of 18 or 22. Yet, since many people are not tested when young, some states allow IQ tests to be given to murder defendants of any age. One intelligence expert worried that we will end up executing only those killers "too stupid to realize that they ought to flunk their IQ test."
The Court's majority stated, "Mentally retarded persons frequently know the difference between right and wrong and are competent to stand trial, but, by definition, they have diminished capacities to understand and process information, to communicate, to abstract from mistakes and learn from experience, to engage in logical reasoning, to control impulses, and to understand others' reactions."
The IQ experts agreed with this, though they cautioned against the Court's overly simplified implication that the mentally retarded are intellectually limited and everyone else is not. Gottfredson observed, "People cannot be lumped into just two categories -- retarded vs. normal. An IQ of 75 is just the point at which the odds of mastering the elementary school curriculum and living independently in modern American society as an adult fall below 50-50."
More controversial among the IQ experts was the Court's assertion that the "deficiencies (of the mentally retarded) do not warrant an exemption from criminal sanctions, but diminish their personal culpability."
Psychometrician Chris Brand, a consultant with the Woodhill Foundation and a one-time staff psychologist at a British prison, agreed.
"My inclination is to say the low IQ do know murder is wrong, but that their grasp and control of their own actions is rather slight when temper or sex are roused or drink is taken," he said.
On the other hand, the death penalty is seldom applied in crimes of passion. It's more likely to be demanded in aggravated cases where the murderer showed logical foresight, such as by killing his robbery or rape victims to prevent them from identifying him.
Some of the IQ experts were skeptical of whether avoiding aggravated murder required much in the way of sophisticated powers of reasoning. (All agreed, however, that individuals with scores below 50 suffered profound limitations.)
Richard Lynn, a professor emeritus of psychometrics at the University of Ulster, suggested, "An adult with an IQ of 70 has the mental age of the average 11.5 year old child, and these will certainly know that killing people is wrong."
Gottfredson suggested, "Most individuals below the 75 IQ level understand the basic rules of society. They know that hurting other people is wrong. They are not uncivilized. I have a mildly retarded brother and he is very aware of moral standards of right and wrong."
Some IQ experts were concerned that the Supreme Court's ruling would make the low IQ appear as morally less than fully human by officially labeling them as inherently less able to comprehend basic ethical rules such as "Thou shalt not kill."
This is an issue of surprisingly broad social importance. The intelligence researchers noted that while IQs below 70 or 75 are extremely rare in the kind of circles that modern Supreme Court justices travel in, they are much more common in other social settings.
The researchers said that the majority of low IQ individuals do not suffer from medical problems such as Down's Syndrome. Gottfredson noted, "About 75 percent-80 percent of mental retardation is called 'familial,' because it mostly just represents the unlucky combinations of genes that are passed in the normal manner from parents to children. Only a small proportion of mental retardation is due to organic problems, such as chromosomal abnormalities or brain damage. This is just like height. Most very short people are perfectly normal."
The stereotype that most low IQ children are what obstetricians often callously refer to in their notes as FLKs - "Funny Looking Kids" is not true. Elite members of American society tend not to realize this because when an extremely high-IQ person, such as a Supreme Court justice, has a retarded child, it's generally due to organic causes.
As children, these "familial" low-IQ individuals fit in well on the playground, where they may be indistinguishable from their higher-IQ friends. They are normal, except that they run into problems when they need to do the higher-order, abstract thinking that a modern society rewards.
Familial low IQ has been quite common in the past, in other countries today, and in segments of American society.
Interestingly, raw IQ scores have been rising around the world for as far back as testing has been performed on a national basis. To deal with this, test developers periodically raise the number of correct questions a test taker must answer correctly to achieve an average score of 100. This means a vast number of Americans in the past would have scored under 70 on today's tests. Lynn conservatively estimated, "In terms of today's IQs, about 16 percent of whites and about half of blacks" would have scored below 70 in the 1920s. Looking back to the early 20th Century, Gottfredson mused, "It is far-fetched to say that half the population then did not know that murder was wrong."
The causes of this rise in unadjusted IQ scores remain in dispute. Both Gottfredson and Brand doubt whether it reflects a real increase in intelligence. Brand has argued that contemporary people are simply better test takers. In contrast, Lynn has published studies showing that improved nutrition has probably caused some of the rise in raw IQ scores.
Other theories trying to account for the improvement, sometimes called the Lynn-Flynn Effect, include better health, more schooling, and a generally more stimulating mental environment due to more intensive urbanization, pervasive media, abundant shopping choices, and the like.
Further, there are quite a few impoverished countries right now with inadequate nutrition, health, and education, where the national average IQ is in the 70s or even the 60s. In Lynn's new book "IQ & the Wealth of Nations" (co-authored with Tatu Vanhanen of the University of Helsinki), he calculated average IQ scores for 81 countries based on 184 studies published in scientific journals. Lynn found that in 15 of the 81 nations, the mean IQ was below 75. (At the other end of the spectrum, Hong Kong came in highest, averaging nine IQ points more than the United States).
Roughly half of the populations of these low-IQ countries would be considered mildly retarded by the U.S. Supreme Court and thus of diminished moral culpability. Yet, while these destitute societies have undeniable trouble competing in global technology markets that require advanced skills, they would certainly reject the Supreme Court's implication that their average adult is of such limited moral capacity that if he murders, he should be treated like a child.
Finally, the Court's decision officially designates that a much larger fraction of the African-American population is of diminished moral capability compared to the white and East Asian populations. About 2 percent-3 percent of whites or East Asians don't exceed 70 on IQ tests, vs. 10 percent-12 percent of American blacks (and more than 20 percent score below 75).
Some of the IQ defenders were quick to point out that Court and the New York Times had implicitly agreed with them that IQ tests were not racially biased. Gottfredson said, "The death penalty may be the only public policy debate involving race in which we are not bombarded with the usual canards about IQ tests being biased against blacks." She contends that abundant evidence shows IQ tests are equally good at predicting a variety of life outcomes for both blacks and whites.