Inaccurate IQs could be a matter of life and death

In many countries, stipulations have been made about sentencing someone to death for a crime if they prove to have such a low IQ as to be considered mentally deficient and therefore incapable of being fully responsible for their actions.

The recent case of Teresa Lewis (IQ 72), who was executed in September last year, was potentially - in hindsight - a miscarriage of justice based upon established case law.

The United States Constitution's Eighth Amendment prohibits cruel and unusual punishment, and in 2002 the US Supreme Court deliberated over the matter, eventually conceding that without sufficient cognitive faculties, suspects were too easily victimized by the circumstances of their arrest and subsequent disposition.

The metric was accepted that an IQ of 70 represents the lower limit of people who can be sentenced to death for a capital crime.

One interesting feature of this 'policy' is the accuracy of measured IQs and how they are applied. A recent article about IQ testing in this regard bears the thread title "Inaccurate IQs could be a matter of life and death".

In it, a UK psychologist seems to have cast a serious doubt on the most commonly used tests to make the determination (as was done in Mrs. Lewis' case.)

...two of the most commonly used IQ tests: the third edition of the Wechsler Adult Intelligence Scale (WAIS-III), which can be used on people aged between 16 and 93, and the fourth edition of the Wechsler Intelligence Scale for Children (WISC-IV), suitable for children aged between 6 and 16.

In both cases, the test manuals state that you can be 95 per cent confident that a person's true IQ lies within 4 points of their test score.

How such claims could be made and accepted as definitive should require some study, but the twist in the tale shows that:

Whitaker found that for people with extremely poor WAIS-III scores, their actual IQ could be up to 16 points higher or 26 points lower than the score achieved. In the WISC-IV test, actual IQ may be up to 25 points higher or 16 points lower than the score achieved.

The range of error was demonstrated and should now make it's way to the Justice system for review... but lacking any motive effort, I don't think it has been, or appears to be on its way to be, considered by the courts.

Now I expected that the math behind the doctors observation would be difficult to explain.... I was wrong;

He [Whitaker] offers a simple explanation for the wide error margins in IQ readings at the low end of the scale. The statistics used to arrive at the 95 per cent confidence level for the tests are based on the IQs of a representative sample of the population. "But by definition, most people in the population have average IQs," says Whitaker. "This causes problems when statistics based on the performance of people with average IQs are assumed to apply to people with low IQs."

It's a good article, worthy of attention.

Enjoy!

Wow I'm glad there are still people that can write threads around here.....

Super interesting stuff.. but IMO, if you kill someone in cold blood... it shouldn't matter what your IQ is... well... unless you get a public defender too....

reply to post by DaMod


Thank you kindly for the compliment.

capital punishment should never happen but i am sure you may get people with high IQ's who are a bit lacking in empathy while you must get complete morons who understand other people have feelings etc.. I think that the stupid should certainly not get any special treatment when they are out commiting murders.