Monday 3 June 2013

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

In yet another engaging and meditative post, Steve Sailer has given us his personal view on his driving errors, reaction times, and intelligence.

With commendable honesty, he shows that he is fully aware that we should not keep ourselves “above the audit”. Every observer is also observable, and must submit to enquiry. Not everyone knows that, or behaves as if it were true.

Like Steve, I depend on the kindness of strangers to make allowance for my driving errors, and I remember clearly my failures to scan the road both ways at apparently quiet junctions. I have (mostly) got rid of the delusion that I am an above average driver. Why does this view prove so popular? One very strong reason is that the distribution of driving errors does not conform to the standard normal curve. Gigerenzer covers this in his mini-chapter “Why most drivers are better than average” on page 214 of his book “Reckoning with risk”. (This book can be quoted to advantage on virtually any occasion).

Most people drive pretty safely. (They avoid errors, but also recall their prudent reactions with pride and attribute their errors to a temporary lapse, which they tend to forget). A minority of drivers keep getting into trouble. This includes many young men, a very few young women, those of any age who drink heavily, those who allow themselves to be distracted by phones and fellow passengers, and some who just cannot control their speeds. In the spirit of Lady Bracknell who admitted: “I myself am peculiarly susceptible to draughts” I should confess that I am peculiarly susceptible to open roads in bright sunshine, though that is not a frequent temptation in England. Mind you, on the sunny road back to London last evening under the dappled, yew-tree-tunnelled shade of Salisbury plain, with not a car in sight, none of these prudent observations were uppermost in my mind.

Anyway, back to the distribution of errors: as a result of this dangerous minority, rather than 50 percent of drivers being above average, the true figure is probably that 63 percent are above the modal accident rate, and are justified in saying that they are, in the common parlance, “above average drivers”. Skewed distributions are difficult to describe in ordinary language, but depict a familiar social problem: that of accounting for behavioural minorities. (It takes us away from the main argument, but this is also true of the minorities who have more than 50 sexual partners, rather than the more usual, contemporary 10).

When I discussed this finding with driving behaviour psychologists some years ago (the driving, not the sex) one gave me an evidence-based and crushing reply: he sent me the self-evaluations he had collected from learner drivers who had only just passed their driving test. This is the period in which there is a sharp spike in accidents and deaths, partly due to sheer inexperience, partly due to showing off to passenger friends after a drinking party at night. These novice drivers habitually rated themselves as being 7 or 8 out of 10, when in fact they were at that stage 3 or 4 out of 10.

This is yet another example of the Dunning-Kruger syndrome: over-confidence and under-competence, a thoroughly lethal combination. It is a cognitive bias in which the unskilled suffer from illusory superiority, and lack the competence and self-reflection to acknowledge their deficiencies. This is a very common disorder, and seems to be inversely related to self-esteem and intelligence. Brighter people note their errors, note their brighter competitors, and are grimly aware of all the stuff they ought to know, but haven’t got round to reading yet (they monitor the external world). Less bright people revel in their accomplishments. They have delusions of adequacy (they monitor their internal world). It is not the purpose of this blog to encourage public abuse, but after being subjected to any sustained burst of self-confident nonsense one is justified in muttering, very quietly to one’s self “Dunning-Kruger syndrome”. I append the reference as a public service to aggrieved citizens who might otherwise be tempted to violence.

Kruger, Justin; David Dunning (1999). "Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments". Journal of Personality and Social Psychology 77 (6): 1121–34.doi:10.1037/0022-3514.77.6.1121. PMID 10626367. CiteSeerX:

Now to Steve Sailer’s reaction times. As already discussed in this blog (Can I have a reaction you should google “BBC reaction time sheep test” and then all of us can get ourselves on a common baseline. Ignore any blogger who does not post their reaction time results. Equally, demand reaction times from would-be commentators on your blogs. (Note that there are artefacts: my standard laptop response key gives poorer results than a new wireless mouse, so if this really bugs you, buy the latest and most sensitive response key you can find).

As Jensen was at pains to point out, reaction times contain two elements: thinking time and movement time. In ordinary life the two are confounded. Faced with an obvious threat, if you keep both of these short you keep alive. In more tricky situations with various options to consider, thinking time becomes the great discriminator, and movement time less significant.

Perhaps Steve is right that Jensen complicated reaction times too much. He was attracted by the beauty of Hick’s Law (speed plotted against the log2 of decision options) with which his results fitted quite well. Ian Deary, on the other hand, finds that simple reaction times predict lifespan, or at least take out a good chunk of the IQ/lifespan variance, suggesting that a common pathway gives us health, reaction speed and intelligence, to varying degrees.

Sport, as I understand it, often involves throwing or hitting balls. Do not ask me why. As far as I am concerned, balls have never done me any harm, particularly when left alone. Propelled at velocity they can be dangerous. For some reason schools pick on serious readers and interrupt their studies by taking them outside and getting them to catch these objects. The trick, for those serious readers who can see the flying object in the first place, is to compute the balls’ parabolic trajectory and the place and time of landing, and thus accelerate themselves into the place where it is most likely to land just at the moment it does so.

Rather than attempting any of this, it would be simpler to note that reaction times, whilst showing a positive correlation, are not very strongly related to measures of intellect. Steve is not the first of my clever readers I have had to reassure on this point.

Steve makes a personal claim: “I'm a reasonably intelligent person”. Claims of this sort are not allowed in England, so I can only look at this American remark with bemusement and envy. However, according to the Dunning-Kruger effect, we cannot take such self-assessments at face value. It is pointless to ask Steve for his IQ measurements, since the intelligence quotient is a summary of a sample of intellectual tasks. It does not have a reified status. It is a predictor (one of the best we have, out of a rather weak bunch) but it is not “that which must be predicted”.   

A detailed look at the corpus of his postings, his analysis of data, responses to arguments and so on confirms his likely high intelligence in the usual meaning of that term: “a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings “catching on,” “making sense” of things, or “figuring out” what to do” (Gottfredson 1994). He also shows an interest in sports, but that is permissible in persons who are otherwise of good character.

Steve makes two additional intelligence-related claims: “There are two intellectual areas where I have very fast reflexes”.

The first area is being fast to get the joke in a movie. I agree that this can be a great, but it is a lonely skill. It leads me to suggest a new IQ test. Skip movies which often have to spend time setting up the context. Take a selection of comics and measure the time between exposure and laughter. Failure to laugh at any three in a row gives you a beautifully embossed certificate of Failure, and a quick exit from the test. The items could be ranked in terms of a priori intellectual complexity, which would be a pleasurable task in itself, and then we could have a good linear scale comprehension test, admittedly rather slanted towards the upper right hand side of the bell curve. (In the spirit of further personal disclosure, today I came across an old copy of the Alice Heim AH5 test for university students, which was used in the 1960s. I can claim to have got a B in this test aged 19, though I doubt I could do that again without resting beforehand for several days. Have a look at some of the items if you can, without breaking copyright).

The second area is Quiz shows involving buzzers. This is a real intelligence test. Anyone who did not test their buzzer before participating fails! Other than that, “first to the buzzer” is the key feature of University Challenge on BBC2, with the proviso that if your answer is wrong ten points go to the other side. Speed matters in a quiz, but speed of thinking matters even more in real life, because faster processors are required to solve harder problems.

Steve says that he “doesn’t get reaction times” but of course he does, it is simply that he knows they are a poorer test of intellect than even something simple like digit span or a ten word vocabulary test. Whilst Steve is probably right about contemporary life, those who belittle reaction time measures are probably wrong about our hunter-gatherer past. In that era one presumes that reaction times were often a matter of life or death. Hence, it might be simplest to keep contemporary reaction time studies simple, and only administer one trial, with minimal warning, so that the test approximates most closely to real life. To my surprise I survived a French driver on a winding hillside road at dusk in the South of France some weeks ago, and was very pleasantly surprised by the speed with which I swerved to avoid him, my passengers less so.

Disclaimer: Some of my above statements are immodest. Modesty about one’s capacities is not only polite, but very probably has high survival value.


  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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