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Tuesday, November 06, 2007

What is Intelligence?

I don't know a lot about this topic, it's psychology not economics, so please add anything you can in comments. This is part of the lead essay to a discussion at Cato Unbound that attempts to answer questions such as "Is intelligence a unitary, general factor — the psychometrician’s famed g — or is it more plural and fragmented? What role do genes play in determining IQ? The environment? If intelligence is in the genes, then why do IQ scores continue to rise generation after generation all over the world?":

Shattering Intelligence: Implications for Education and Interventions, by  James R. Flynn, Cato Unbound: The concept of a general intelligence or g factor has proved enormously fruitful in two respects. On the level of individual differences, it captures the fact that if one person outperforms another on one kind of conceptually demanding task, that advantage is likely to persist over a whole range of other cognitive tasks. ...

An example of a good IQ test is the WISC (Wechsler Intelligence Scale for Children). The reason it is good is that its ten subtests have enough cognitive complexity so that a high IQ person tends to beat the average person by a handy margin on all ten. That is equivalent to saying that it is a good measure of g. A test that included subtests of minimal cognitive complexity, let us say tying your shoes, would be a bad IQ test. The task is so simple that unintelligent people would perform it as well as intelligent people.

Shattering general intelligence Despite all the triumphs of the concept of general intelligence, I believe intelligence is like the atom: you have to know both why its parts cohere and why they sometimes fly apart. Americans made massive IQ gains on the WISC between 1947 and 2002 amounting to almost 18 points... These gains ranged from only 2 points on the WISC subtest called Information to 24 points on the subtest called Similarites (what do dogs and rabbits have in common?), despite the fact that both have the cognitive complexity that makes them good measures of g.

A bright person tends to accumulate more general information than a dull person at any given time and also tends to better at classifying things (will say that dogs and rabbits are both mammals). But over time, we find that society can develop these conceptual skills quite independently of one another. Children may progress a lot over time in putting on scientific spectacles, which means that many more of them will say “both mammals” rather than say something like “I use my dog to hunt rabbits.” While thanks to the rise of a visual culture that discourages reading, the average child today may have no greater store of general information than children did 55 years ago.

Diagnosing how conceptual skills actually develop The fact that various conceptual skills develop so independently over time has wide implications for education. ...

Once you break intelligence down into its autonomous components, many things become clear. For example, the Nation’s Report Card shows that today’s children are ahead of their parents in reading at early ages and then the gains fade away by the age of 17. How is that possible? The children are doing much better on heavily g loaded IQ tests like the WISC at all ages. Should not brighter people be able to read adult novels better?

This mystery is solved when you look at IQ trends over time. Since 1972 (when the NRC began), the big IQ gains have been on certain subtests and not others. There have been virtually no gains in vocabulary and information. You cannot enjoy War and Peace very much if you have to run to the dictionary or encyclopedia every other paragraph. We are doing a better job of teaching children the mechanics of reading at early ages. But their parents had mastered the mechanics by age 17 and at that age, neither generation has an information or vocabulary advantage. So we have made no progress is teaching young people how to enjoy adult literature. ...

The transience of intelligence General intelligence or g has something to do with brain quality, and good genes have a lot to do with having an above average brain. Therefore, there was a tendency in differential psychology to think that our genes-determined brain accompanies us throughout our lives and that environment, except in extreme conditions (living with wolves since infancy), merely leaves minor imprints on that brain. After all, twin studies showed that even when identical twins were separated at birth, they had IQs at adulthood that were much more similar than the IQs of randomly selected people. What better evidence did you need that genes/brain went though life and environment just did a bit of tinkering along the way?

But this created a dilemma: if genes were so dominant, how could IQ gains over time be so huge? Unless you thought that there was a large genetic upgrading from one generation to the next, large intelligence gains should be impossible. Yet they occurred, which implied that there were environmental factors of huge potency. How could environment be both so feeble and so potent?

The Dickens/Flynn model resolved this dilemma. Two twins raised apart, thanks to having slightly better genes than average, would both get into increasingly privileged environments. Both would get more teacher attention, would be encouraged to do more homework, would get into a top stream, and by adulthood, they would both be far above average. ...

This means a huge shift in perspective. The g-man view was that environment made little difference throughout life because environment makes very little difference at any point in life. The Dickens/Flynn view is that environment makes a lot of difference, which meant we had to look elsewhere for why its effects seem so transient. Our conclusion was that present environment swamps past environment in terms of effect on your level of cognitive functioning.

Cognitive exercise The first implication of the new perspective is the benefit of persisting in cognitive exercise throughout life. ...

The brain is much more like our muscles than we had thought, even in the sense that specialized exercise affects different parts of the brain. Autopsies show that the brains of London taxi-drivers are peculiar. They have an enlarged hippocampus, which is the brain area used for navigating three-dimensional space. Here we see spatial abilities being developed without comparable development of other cognitive skills. To develop a wide variety of cognitive skills you need a wide variety of cognitive exercises...

Three levels and three concepts All of this has implications for the theory of intelligence. There is nothing really the matter with the concept of g; it is just that we have misused it by making it the omnipresent concept in our study of cognitive abilities. Intelligence is important on three levels, namely, brain physiology, individual differences, and social trends (collectively, BIDS). The core of a BIDS approach to intelligence is that each of those levels has its own organizing concept, and it is a mistake to impose the architectonic concept of one level on another. We have to realize that intelligence can act like a highly correlated set of abilities on one level and act like a set of functionally independent abilities on other levels. ...

As for individual differences, that is the proper kingdom of g. There is simply no doubt that performance differences between individuals on a wide variety of cognitive tasks are correlated primarily in terms of the cognitive complexity of the task or the posited cognitive complexity of the path toward mastery. However, we need to avoid the mistake of thinking that the interaction between genes and environment is less complex than the reality.

On the social level, it is also beyond doubt that various real-world cognitive skills show different trends over time as a result of shifting social priorities. The appropriate dominant concept on this level is not g but something like social utility.

In closing, I want to stress that the BIDS approach does not aim at the abolition of g. It merely endorses a separation of powers that gives each dominant construct the potency needed to rebuff the other two. The U.S. Constitution attempts to make the President, Congress, and Supreme Court dominant in the executive, legislative, and judicial areas, respectively. I want the same kind of separation of powers for the three levels of intelligence.

    Posted by on Tuesday, November 6, 2007 at 02:16 AM in Economics, Science | Permalink  TrackBack (0)  Comments (46)

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