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  • Print publication year: 2010
  • Online publication date: June 2012

6 - The Mechanics of Intelligence


I believe I have an unfair edge over most of my colleagues right now – my mind works better than my mouth does.

U.S. Senator Tim Johnson, from a speech in Sioux Falls, South Dakota, announcing his intention to return to the Senate following a brain hemorrhage that left his speech impaired, August 28, 2007

Psychometric theories use what Sternberg has called a geometric analogy for intelligence; people are seen as varying along dimensions of intelligence in much the same way that they vary along the dimensions of height and weight. Different theories identify different dimensions, but the geometric analogy is maintained. This is a useful way of summarizing variations in intelligence across populations, but it has a serious shortcoming. The geometric analogy does not explain the processes that make up thinking.

To see what this means, imagine two individuals, Ignatz and Horatio. We first determine their psychometric intelligence, in terms of the g-VPR model, and then ask them to attack the following two problems. The first problem makes use of the English rules that permit center embedding, putting one relative clause inside another. Ignatz and Horatio are presented with sentences of the form

The rat ate the cheese

The rat the cat chased ate the cheese

The rat the cat the dog scared chased ate the cheese

The rat the cat the dog the man owned scared chased ate the cheese.

And so on

and we determine at what point each person finds the sentence incomprehensible.