Monday, 3 June 2013

Steve Sailer’s reaction times, his driving record and his intelligence






















  1. When I had been at university for a week or so a final year psychology student asked me to take a test. It turned out that I had to remember strings of digits and recite them back to him. I did so badly that he told me to give up immediately; it was inconceivable that I would ever graduate.

    His methods had a flaw which he had not had the sense to investigate. I came from a place so rural that our telephone numbers had three digits - I'd never had to use a longer number in my life. 3.14, 212 F, 9.81 m/s^2; nothing had more than 3 digits. Even c = 300,000 km/s really involves only 2 digits.

    What a chump.

    Which raises a more general point: aren't there going to be limitations on the ability to measure IQ caused by, if you'll forgive my saying so, the fact that psychologists will often be substantially dimmer than their subjects, especially when they are testing undergraduate subjects?

    1. It is always humbling when subjects are brighter than the tester. I made a point of highlighting this in my post-test feedback sessions. In probability terms it happens with very roughly 1 in 50 of the general population. As to digit span, it is a reasonably good predictor of intelligence, particularly when several trial are administered. Very short digit spans are more diagnostic than long ones: 3 or less remembered digits is often a sign of mental handicap, long digit spans may or may not be particularly significant.

    2. "roughly 1 in 50 of the general population": aye, but when a psychology student is testing freshers in medicine, vet, physics, maths, and so on?

    3. Testing such freshers is not a usual task in clinical practice, but might be an issue with very bright subjects in research. I once tried to work out what level of intelligence was required to give a Wechsler intelligence test, and 115 should be enough. You don't have to be clever, just diligent enough to follow the manual.

    4. What about the chaps who devised the test?

    5. The point is that there are many tests of short term memory which do not involve digits. STM is predictive of other intellectual skills. Reliability is low if you carry out only a few trials, but with more trials reliability improves. From a theoretical point of view it is one of the few IQ subtests with a true zero, and a proper ratio scale. In a weaker sense Vocabulary is also a true scale resulting in a total number of known words, but in the average IQ test these are crudely estimated. Newer, computer based tests can calculate the word store much more accurately. is a good example, and fun to do, and takes very little time.

    6. 32800 words. It would be interesting for the people on this site to take both an SRT and the vocabulary test, and correlate the scores.

  2. I’ve taken these before, but Michael says there is little SRT practice effect. Pretty bad... ;-)

    sheep: 0.3262
    red/green: from 0.254 to 0.658; average: 0.3958 (large SD, which is a good predictor of low g)

  3. Raw correlations of 0.3 between RT and g are interesting, but hardly convincing in making a prediction about an individual, particularly when other measures are available.

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