10 January 2012

IQ Tests

A while ago, I wrote a review of the book The Myths of Standardized Testing.  The main thrust of the book was that tests of knowledge are remarkably limited in their ability to measure what they claim to measure, and that test results don’t correlate well to future academic outcomes.  The same, I believe, is true of IQ tests.

In the first place, intelligence is defined in a specific, rather narrow way.  Intelligence, as measured by the test, seems to consist of a form of logical reasoning and relational aptitude (e.g. cats:dogs :: shoes:?).  This definition is not inherently wrong, for tautologies never are, but it is very limited, for this tautology necessarily ignores certain types of intelligence and skills.  Again, though, that’s the point.

Secondly, the results of intelligence tests are quite narrow.  It’s not simply that the content of the tests is inherently limited, but also that the method of testing is itself quite limited.  Performance is generally measured one, and rarely more than a couple of times.  This performance necessarily has a time component, and so, when all is considered, IQ tests not only measure a very limited type of intelligence, but that measurement only considers how that intelligence is shown in a very specific format at a very specific point in time.

Fortunately, IQ tests are objective in their standards (in that they test for known properties in a specific way, with objectively correct answers), which means that IQ tests make use of decently-sized samples, which in turn leads to generally reasonable generalizations, particularly when a given individual takes an IQ test multiple times.  However, trying to divine a high degree of specific knowledge from a single IQ test is a fool’s errand, in part because of the narrowness of the test, and in part because intelligence is dynamic.

Thus, IQ tests are a very limited way of measuring intelligence.  The metrics are arbitrary and results are narrow but objective.  This doesn’t mean that IQ tests are worthless—each must determine for himself how much validity the IQ test is to be given—but at the same time they are not the end-all definition of intelligence.  The results of IQ tests, then, are best spoken of in general terms (e.g. a fifty-point difference in IQ scores or more significant than, say, a two-point difference in scores).  In all, the results of IQ tests should be used carefully, which is to say they should neither be ignored nor cited exclusively.

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