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Saturday, January 24, 2009

Psychometrics links

Retired physicist Bob Williams writes: "... I have studied psychometrics and intelligence research for about 17 years and have gotten to know almost all of the current researchers through my membership in the International Society for Intelligence Research. I attend the conferences and discuss the recent studies with the people who have done them."

He sent me the following interesting links:

Summary of research on heritability of intelligence

Diminishing influence of g at high end of ability

Summary of research on evolution of human intelligence

From Williams' notes on ISIR 2007: a discussion with James Flynn:

The interviewer was David Lubinski (Vanderbilt). He started the interview by asking Flynn to tell us about his life. From that point on, Lubinski only managed to get in a dozen or so words. Once the camera started, Flynn launched into an enthusiastic discussion of himself and his ideas. He made a favorable impression from the start by telling us that he grew up in a Catholic family and has become a serious atheist. He also immediately told us of his well known (socialist) political orientation and did not ever attempt to disconnect his political notions from his thoughts about intelligence and the secular rise that bears his name. Flynn speaks clearly and with a loud voice, which was well suited for the interview and later became something of a tool for overpowering people with whom he disagreed. In spite of this, I found him to be very likable, smart, and complicated. He occasionally took positions that were diametrically opposed and admitted that he had done so.

Flynn mentioned his first article (1984), showing a 14 point gain over 30 years (I may have gotten the span wrong, but I think this is correct). In 1987 he published a paper that showed the largest gains were on the Raven’s tests. He has found little, if any, gain in vocabulary. It is well known that FE (Flynn Effect) gains have been greatest in tests of abstract reasoning and least in tests that relate to scholastic items. This contrast immediately suggests that the FE gains have not been g loaded, since g loaded gains would necessarily boost all cognitive tasks. Flynn has not discussed this. I asked him what portion of the gains were g loaded and he went into his history discussion, then finally said “I don’t know.”

Flynn has approached the FE as a matter to be discussed qualitatively, without the support of carefully constructed research studies. Throughout his talk (this was an interview, but it turned into a speech), he described intelligence as a factor with historical variability. His debate with Charles Murray is available on the web and contains the same illustrations that he used in the “interview.” His bottom line is that test items have become easier over time, not because people are more intelligent, but because the items being tested have taken on a more central role in their lives. This makes sense with some test items (vocabulary, for example, but that is one area where he has found little increase), but is not at all apparent with respect to other test items, some of which are unrelated to daily experiences (just look at the list of subtests used in the W-J III).

He mentioned reaction time tests and simply discarded them as not important. This is not so easy to accept, given that a battery of RT tests can produce a very highly g loaded discrimination, yet chronometric measures have not been shown to change over decades. Meanwhile, Flynn was positive about the future of brain imaging and seemed willing to accept future results, even if they support causation that is opposite of his preference. He expects that such research will ultimately find a physiological seat of g. I fully agree, but also find this comment to be in conflict with his arguments from the Dickens-Flynn paper (Heritability Estimates Versus Large Environmental Effects: The IQ Paradox Resolved).

Interestingly, Flynn does not believe that the FE will narrow the B-W IQ gap. Some environmentalists have argued that it will, but no evidence has surfaced to show that after decades of rise, the FE has actually narrowed the gap.

Flynn admitted to having been fired twice and explained that those events prompted him to move to New Zealand. He claims to have defended Larry Summers, James Watson, and Chris Brand. ...In these areas, Flynn shows himself to be both honest and inconsistent. He is inherently likable and extraverted, although I remain of the opinion that he is less interested in discussion than in lecturing. I talked to him for a while at a reception and found him to be pleasant, polite, and sharp.

During his commentary, Flynn said that he favored affirmative action. In fact, he showed a strong interest in finding ways to help blacks overcome various obstacles. When Gottfredson questioned him about affirmative action, he said he is not a fanatic on the subject and admitted that it is unfair to whites. He said that, when employers want to hire a black worker, they are generally unconcerned with whether the employee is outstanding or average.

He attributed at least some of the FE gains to decreasing family size and noted that it cannot go much lower. When I had a chance to talk to him, I asked what portion of the FE gains he believes are g loaded. After repeating his historical perspective, he said “I don’t know.”

From notes on ISIR 2008

Jan te Nijenhuis

The Flynn effect in Korea

• United States FE rate, 3 points per decade.
• Scandinavia, recent slight reversal (IQ decrease).
• Estonia, recent gains.
• Japan, for those born from 1940 to 1965, 7.7 points per decade.
• Korea and Japan, same gains.
• Korea experienced an explosion in education and height of 1.5 to 2.0 SD.

The study involved two formats. One was to use single Raven’s test comparisons for two groups for 1952 and 1982. The other was to test a single group with two tests that were normed 30 years apart. The Koreans gained at about the same rate as did the Japanese, but delayed by 20 to 30 years. The gains have not yet leveled off or reversed.

Some useful references on this topic:

The Structure and Measurement of Intelligence

Genius: the natural history of creativity,

both by Hans Eysenck.

The g-factor, by Arthur Jensen

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