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Earth has not anything to show more foul

As these things go, it was not too bad. One idiot in a car murdered 3 people, with 7 more in a critical condition who may die, at least 40 with terrible injuries, and many more people traumatized. Crowds of tourists ran away from the place of slaughter at Westminster Bridge.

Earth has not anything to show more foul.

From the terrorists’ point of view, they got lots of publicity for minimal outlay, the economics of a Spam email.

The first casualty of terrorism is innocence. Despite bombings, London retains a trusting perspective, a relic of a former age, when it relied on an unarmed police force, on the assumption that nothing else was required. Seen from a generational point of view, England became more peaceful than the Continent in the late Middle Ages, a change usually attributed to Common Law, on the basis that a well-functioning legal system relieves victims of the motivation to wreak their own revenge. Citizens gave up their personal weapons a century ago, and took up politeness, already a national habit.

Years ago a neighbour, woken at night by the sounds of a thief breaking into my car in the street below, leaned out of her bedroom window and asked him: “Can I help you?” in an accusing tone of voice. “And do you know what?” she continued, affronted, “he glared at me before he ran away”.

The event in Westminster, while unpredicted, became predictable as it unfolded. Pedestrians were knocked down and crushed, and then a policeman stabbed to death, until the assailant was shot dead. A script has been laid out for aspiring Jihadis: use a car or lorry as a weapon to kill the public, and then die in a supposed blaze of glory. It is a simple, destructive meme, easily propagated, all too readily believed.

BBC television coverage was informative, repetitive, often using snatches of videotape out of time context in a sloppy way; and too keen to interview other journalists, and eventually prone to hyperbole: “an attack on the heart of our democracy”. Of course Parliament is a symbol, but a policeman stabbed anywhere in London is an affront to a peaceful society. Being held out of harm’s way in a Parliamentary office is very stressful, but no ordeal compared to those shattered on Westminster Bridge.

As the event unfolded the kabuki-like circumspection of BBC reporting began to grate on my nerves, whilst I also respect the need for caution until facts are in. However, in the modern world the facts come in fast and furious. I got the first news on a tweet, something like: “I have just seen a man shot outside Parliament” and then went to the BBC website to be told only that, as breaking news, there had been an incident related to Parliament, and nothing else. The first account I saw came from Radoslaw Sikorsky, with a video of the mayhem and injuries on the bridge, and a clear account of what he had witnessed, and a recording of the taxi driver contacting the emergency services, clearly and calmly. As a consequence, one part of the story was already clear, widely available, and blindingly obvious. TV news was just playing catch up. For a long while the news reported that there had been two incidents, one on the bridge and the other outside Parliament, even though the incidents were separated by about 60 yards and at the most a few minutes. Circumspect, but a bit silly.

Reporters talked primly about things they had seen “on social media” but when that included live recordings of events they eventually included them in their broadcasts. Citizens were the victims and also the first attenders and the first reporters. Still, I respect official reporters for keeping their distance from the dead and dying, and not jumping to conclusions. The audience can wait: their needs are not paramount.

westminster people helping

“I will not speculate” said the Police spokesman some hours later. Fine, we understand that if there is a trial you do not want to provide any surviving assailant with a defence. However, one day I hope they will be able to say: “Our preliminary hypothesis, based on modus operandi and appearance, is that this is yet another Jihadi, of which there are potentially so many”.

For a while there was a swirl of rumour reported on TV that the dark-skinned assailant had been accompanied by a white man carrying two knives. A Member of Parliament whose staff had seen the incident from their office window said that they had seen no such thing, but the “other assailant” theory ran for a while. It may be a Piagetian equivalence: if bad things happen to lots of people there must have been lots of bad men. No, an idiot with a large vehicle can kill many people, and still be a single idiot. One man can shoot John Fitzgerald Kennedy dead, even though he is much more important than Jason David Tippit, whom he also shot dead.

It was impossible not to notice, in the midst of the mayhem, how some witnesses were more able to describe what had happened than others. It was not only the profound emotions, but the task of explaining to those who did not know the Parliamentary buildings and the terrain, and where they were going, and at what time. Explaining requires a good theory of mind: what is obvious to you will not be so to your listener. This is well known in disaster research. Some witnesses just name who they were with, others state the relationship for the benefit of the listener.

It is highly irritating to hear journalists say of fleeing pedestrians that they were in a state of “panic”. Running away from a terrorist stabbing people is exactly what any sensible person should do. In true panic pedestrians would be running towards the assailant, or waiting to be told what to do, or checking their baggage. Being absolutely calm and staying within stabbing distance is not a wise policy. People were frightened, very frightened and that was a very sensible reaction.

It is only my lay impression, but Carriage Gate (the entrance where the assailant stabbed and killed the policeman) will need to be reviewed. It seems that every time I drive past, the gates are always open. I doubt that unarmed police could cope with both a vehicle ramming in and a group of armed men pushing in at the same time. Also, Westminster tube station had no way of knowing what was happening on their doorstep until an MP told them, on no authority other than her good sense, to close the station to new arrivals. That needs a review.

This morning the news revealed that 8 people have been arrested, many in Birmingham, where a few wards of the city are disproportionate suppliers of Jihadis. Community leaders made the usual comments about the need not to alienate those local communities. What is the subtext to those cautionary statements? The implied threat is that alienating the community from which assailants are drawn will make them increase the supply.

westminster london attacker
Was it a failure not to have spotted this guy, described as “British born”, by which of course they mean “born in Britain, but not British as you would be used to think of it”? He had been on the radar of the security services, but was judged peripheral. In my view, no real failure. There are too many Muslim men talking Jihad to be able to spot the one that turns from preparation to the completed act. There is little doubt as to the group one should be monitoring. This is a time for Bayes, not wishful balderdash. Concentrate on the source of supply and you reduce the false positives, though you can never be sure of identifying the signal in a cacophony of hostile noise.

What can one say about the “militant and proselytizing faith of Islam”? I will leave that to a statesman who made his reputation defending freedom.

How dreadful are the curses which Mohammedanism lays on its votaries! Besides the fanatical frenzy, which is as dangerous in a man as hydrophobia in a dog, there is this fearful fatalistic apathy. The effects are apparent in many countries. Improvident habits, slovenly systems of agriculture, sluggish methods of commerce, and insecurity of property exist wherever the followers of the Prophet rule or live. A degraded sensualism deprives this life of its grace and refinement; the next of its dignity and sanctity. The fact that in Mohammedan law every woman must belong to some man as his absolute property, either as a child, a wife, or a concubine, must delay the final extinction of slavery until the faith of Islam has ceased to be a great power among men.

Individual Moslems may show splendid qualities. Thousands become the brave and loyal soldiers of the Queen; all know how to die; but the influence of the religion paralyses the social development of those who follow it. No stronger retrograde force exists in the world. Far from being moribund, Mohammedanism is a militant and proselytizing faith. It has already spread throughout Central Africa, raising fearless warriors at every step; and were it not that Christianity is sheltered in the strong arms of science, the science against which it had vainly struggled, the civilisation of modern Europe might fall, as fell the civilisation of ancient Rome.
Winston Churchill. The River War: An Historical Account of the Reconquest of the Soudan (1899), Volume II pp. 248–250

Strange to see his statue apparently witnessing the event from a few yards away.

Driving into London last night everything seemed as before. Restaurants were in full flow, though with fewer people outside because it was a cold evening. It was personally reported to me that many Government employees regarded “lockdown” as an imported absurdity, and let themselves out of the back doors of their departments so as to carry on with their engagements, walking along Whitehall and the Strand in order to do so. Other offices declared “lockdown” because it seemed fashionable, but staff went out from side entrances to get coffees anyway, despite it taking them closer to the scene of the event. The London Eye (large Ferris wheel) was not only stopped, but people were left in it. Sure, don’t let new people on, but why not let people off? It would be good to let citizens make their own risk assessments, and not ensure that these tragic and terrible events become an excuse for widespread paralysis of city life. Returning by car after dinner took a bit longer, because the roads near Parliament were still closed, but everything was peaceful.

The river glideth at his own sweet will:
Dear God! the very houses seem asleep;
And all that mighty heart is lying still!

• Category: Science • Tags: Terrorism 

It has been dryly observed that many people involved in the Northern Ireland peace process did so without having been terrorists first. Perversely, a terrorist who changes course when murder proves unfruitful as a sole strategy is seen as having made a greater contribution than those who were always whole-heartedly in favour of peaceful politics. By some absurd logic, ex-terrorists are commended for having travelled further on some journey of discovery. Greater the sinner who repents than the victim who was walking along the street, who has renounced nothing but limbs or life.

I provided services to some of those, and one of my friends held the hands of the dying at the Harrods bombing, bodies severed by plate glass. We ran a trauma clinic together. Does this make my opinions less valid? Could be.

I understand the need for realpolitik. I agree with Churchill’s observation:

The reason for having diplomatic relations is not to confer a compliment, but to secure a convenience.

In searching for that convenience lives were probably saved, at the cost of altering course in accommodation to violence.

Can anyone remind me of the name of the journalist, I think an American, who began his interview with the other IRA leader by saying: “Tell me, do you do the actual killings or just the PR for it?”


Saturday is a relative slow day in my household, so it felt somewhat of a rebuke to read on the BBC that the Tsimané people have an ideal lifestyle, walking some 17,000 steps a day, as compared to the lethargic wealthy West, who aim for 10,000 daily steps but rarely take them.

Those of you who are too sunk in lassitude to read the news item will probably certainly not strain yourselves to click on the link to the Lancet article on which the item is based.

Let me save you time and effort by summarizing the main points:

The Tsiname people do not have clogged arteries.

17% of their diet is game including wild pig, tapir and capybara (the world’s largest rodent). 7% is freshwater fish including piranha and catfish. Most of the rest comes from family farms growing rice, maize, manioc root (like sweet potato) and plantains (similar to banana), topped up with foraged fruit and nuts

72% of calories come from carbohydrates compared with 52% in the US. 14% from fat compared with 34% in the US, Tsimane also consume much less saturated fat. Both Americans and Tsimane have 14% of calories from protein, but Tsimane have more lean meat.

Since it is the BBC, there must be a show of editorial balance, and this was achieved in a glancing fashion:

One idea is that intestinal worms – which dampen immune reactions – could be more common and this may help protect the heart.

Note that this is presented as just an idea, not an established fact.

Since it is a BBC story, every noble story has a moral at the end.

Prof Gurven said: “We need a more holistic approach to physical exercise rather than just at the weekend. Bicycle to work, take the stairs, write your story on a treadmill desk.”

Dr Thomas said: “To maintain health we need to be exercising much more than we do. The modern world is keeping us alive, but urbanisation and the specialisation of the labour force could be new risk factors [for an unhealthy heart]. They also live in small communities, life is very social and they maintain a positive outlook.”

Dr Gavin Sandercock, reader in clinical physiology (cardiology) at the University of Essex, said: “This is an excellent study with unique findings. The Tsimane get 72% of their energy from carbohydrates. The fact that they have the best indicators of cardiovascular health ever reported is the exact opposite to many recent suggestions that carbohydrates are unhealthy.”

Prof Naveed Sattar, from the University of Glasgow, said: “This is a beautiful real life study which reaffirms all we understand about preventing heart disease. Simply put, eating a healthy diet very low in saturated fat and full of unprocessed products, not smoking and being active life long, is associated with the lowest risk of having furring up of blood vessels.”

By this stage you may be reconsidering your plans for this Saturday, cancelling your lunch engagements and setting off on a long run, with some game hunting on the side. However, I am steeped in Anglo-Saxon skepticism, so I thought this uplifting tale was worth a few minutes of research.

My first thought was that clogged arteries are only one risk factor, and that one should take a more rounded view of the health of this tribe before coming to any conclusions. My next question was whether they had done any genetic research, since this was an obvious confounder, or better, a gateway into understanding the genetics of cardiac disorders. A third question, although not fully formulated, was “Worms, what sort of worms?”

A glance at gleans the following:

The average Tsimané woman has nine children in her lifetime. A study of 983 Tsimané women found that 70% were infected with the parasitic roundworm Ascaris lumbricoides, which is believed to have increased their fertility rate by suppressing their immune system, leading to two additional children over the course of a lifetime.[10]

The parasite effect on fertility is one for Greg Cochran, who notes that parasite can sometimes alter host behaviour to their apparent advantage:

There is some epigenetic work on this tribe, but of more importance in my view is that there are some genetic differences, probably indicating that variants are under selection in response to a high infection environment.

Apologies for making you do all this energetic clicking, which can be exhausting, but here is a more detailed account of the tribe by one of the authors:

The key point, as I see it, is that the BBC is implying that you have much to learn from the Tsiname, without telling you a relevant fact:

Average life expectancy at birth was 43 years between 1950-89 and increased to about 50 during the period 1990-2002. Half the population is under 15 years of age.

Cannot write more because I have to drive to the supermarket.

• Category: Science • Tags: Diet 

Despite being interested in intelligence, I am also on guard against judging the mind from the face (there’s no art to find the mind’s construction in the face) while probably doing just that all the time. I assume that I judge mental ability by conversations which go beyond pleasantries. Indeed, perhaps measuring how quickly people turn from pleasantries to content is an ability measure in itself. However, I have never knowingly made a judgement about a person’s intelligence by estimating pupil size. Perhaps I should.

J.S. Tsukahara, T.L. Harrison, R.W. Engle (2016) The relationship between baseline pupil size and intelligence. Cognitive Psychology Volume 91, December 2016, Pages 109–123


Pupil dilations of the eye are known to correspond to central cognitive processes. However, the relationship between pupil size and individual differences in cognitive ability is not as well studied. A peculiar finding that has cropped up in this research is that those high on cognitive ability have a larger pupil size, even during a passive baseline condition. Yet these findings were incidental and lacked a clear explanation. Therefore, in the present series of studies we systematically investigated whether pupil size during a passive baseline is associated with individual differences in working memory capacity and fluid intelligence.

Across three studies we consistently found that baseline pupil size is, in fact, related to cognitive ability. We showed that this relationship could not be explained by differences in mental effort, and that the effect of working memory capacity and fluid intelligence on pupil size persisted even after 23 sessions and taking into account the effect of novelty or familiarity with the environment. We also accounted for potential confounding variables such as; age, ethnicity, and drug substances. Lastly, we found that it is fluid intelligence, more so than working memory capacity, which is related to baseline pupil size. In order to provide an explanation and suggestions for future research, we also consider our findings in the context of the underlying neural mechanisms involved.

The authors explain:

Starting in the 1960s it became apparent to psychologists that the size of the pupil is related to more than just the amount of light entering the eyes. Pupil size also reflects internal mental processes. For instance, in a simple memory span task, pupil size precisely tracks changes in memory load, dilating with each new item held in memory and constricting as each item is subsequently recalled (Hess & Polt, 1964; Kahneman & Beatty, 1966). This research established the use of pupil dilations asan indicator of momentary changes in arousal, mental effort, and attention (Beatty & Lucero-Wagoner, 2000; Hess & Polt, 1960).

Because pupil dilations occur for a wide variety of tasks involving mental effort, psychologists had inferred that the task-evoked pupillary response was reflective of central brain processes (Beatty, 1982). For some, this was seen as providing an opportune way to study the dynamics of cognitive brain function (Beatty & Lucero-Wagoner, 2000). Until more recently, though, the method of measuring pupil size to study brain function did not gain much traction in the field. It was suspected that the reason for this was, ‘‘pupillometry is not widely employed in cognitive psychophysiology because the pupil lacks face validity as a measure of brain function” (Beatty & Lucero-Wagoner, 2000).

In a simple memory span task, pupil size precisely tracks changes in memory load, dilating with each new item held in memory and constricting as each item is subsequently recalled. High memory span subjects had larger pupils than low span subjects even during a ‘‘passive” baseline (in the absence of performing any specific cognitive task). Baseline pupil size was measured during a ‘‘passive” baseline while subjects stared at a fixation on a computer monitor.

In their first study 20 subjects with low working memory were compared with 20 subjects with high working memory on a simple letter span task, and had their pupil size measured before doing the task.

High working memory subjects’ pupil diameters were 0.97 millimeter larger than those with low WMC, a difference which is usually visible to the naked eye.

Iris and memory load

The change in pupil diameter over levels of memory load, seen in Fig. 1 reflects the increase in mental effort. The important finding was that pupil diameter increased as a function of memory load by the same amount for high and low working memory subjects.

Being cautious persons, the authors ran a second study to test whether familiarity with the university setting might have accounted for the difference. Their bright subjects were drawn from the university, the less bright ones from the general community, a possible source of considerable bias. Over three sessions they were able to show that familiarity of the environment does not account for the relationship between WMC and pupil size. Both groups got more used to the test setup after a few sessions, at roughly the same rate. Furthermore, the reliability of pupil size over time is high, as indicated by the high correlations ranging from 0.77 to 0.84. In these 102 subjects, average pupil diameter positively correlated with fluid intelligence at r= 0.37 which is a reasonable size for an indirect measure of this sort.

However, the comparison of high and low working memory groups is an extreme group design that can sometimes force a desired result. So, in Study 3 they studied the full range of intelligence on a large experimental sample. This is very welcome, and here are their procedures:


A total of 358 subjects took part in four 2-h sessions in which they were tested on a wide-variety of cognitive tasks. No subject had participated in a study in our lab previously. Subjects were between the ages of 18–35 and had corrected-to-normal vision. Due to technical issues with the eye-tracker, unable to calibrate eye-tracker, or excessive amounts of missing baseline pupil data, the total number of subjects was reduced to 337.

Materials and procedure

Subjects participated in four sessions that lasted approximately 2 h in which they completed a battery of cognitive tasks. Included in this battery were the measures of working memory capacity (WMC) and fluid intelligence (Gf) described below.

We measured baseline pupil size at the beginning of Session 4 before subjects started any tasks for that day. Immediately following baseline pupil measures subjects performed a simple memory-span task to measure task-evoked pupil dilations.

Measures of working memory consisted of the operation span, rotation span, and symmetry span tasks. Measures of fluid intelligence consisted of the Raven Advanced Progressive Matrices (Raven et al., 1998), Letter Sets (Ekstromet al., 1976), and Number series (Thurstone, 1938).

Given that the size of the pupil is affected by a variety of factors besides locus coeruleus activity, such as age and some drug substances, it is important to account for these. Nine different demographic variables were assessed: Ethnicity, Age (in years), College Student, Nicotine, Medications, Gender, Handedness, Caffeine, Alcohol, Sleep. All demographics were self-reported. At the end of Session 4, the same day as pupil measurements, subjects were asked about: the amount of sleep they got the previous night, their use of nicotine (in the last 10 h), medications (that might affect their attention and memory, in the last 24 h), caffeine (in the last 8 h), and alcohol (more than two drinks in the last 24 h).

Working memory explained 6% of the variance in baseline pupil size and with each 1 SD increase in WMC there was a 0.30 mm increase in baseline pupil diameter, b = 0.30, r = 0.24. Fluid intelligence explained 12% of the variance in baseline pupil size and each 1 SD increase in Gf was associated with a 0.45 mm increase in baseline pupil diameter, b = 0.45, r = 0.35.

Fluid intelligence, however, still predicted baseline pupil size after controlling for WMC, b = 0.45, r partial= 0.27, p< 0.05. These results provide strong evidence that it is fluid intelligence, not working memory, which is uniquely related to baseline pupil size.

What we have shown is that individual differences in fluid intelligence is related to differences in baseline pupil size. However, at this point, our brain story of the intelligence – baseline pupil size relationship is only reasonably informed speculation. Further research is needed to follow up on our findings if we want to draw any definite conclusions about the underlying neural mechanisms.

What are we to make of this? There was a period in which intelligence researchers were drawn to surrogate intelligence measures, which did not run into the storm of criticism which surrounded IQ tests. Reaction time, choice reaction time, tachistoscopic inspection time, analysis of EEGs and the like. Here is a more recent study, using illusory movement to measure a “Motion quotient”.

Far more detailed work has been carried out using modern scanning techniques, for example showing increases in glucose uptake while solving difficult problems.

I see this as a convergence of lines of evidence showing, as if it were necessary to spell this out, that intelligence is tested whenever people are presented with problems, and among all the things going on in the brain, pupil size varies by the difficulty of the task, and varies by the ability level of the subject solving the task even when at rest and not solving problems, dilated pupils being an indicator of higher ability.

All grist to the mill.

• Category: Science • Tags: Eyes, Intelligence 

Blade Runner had an impact on me, both as a film and because it was an introduction to the writings of Philip K Dick, whose whimsical work was based on wondering what it meant to be human. Are we as individuals merely constructions of fundamental genetic coding mechanisms, which create treasured but probably false memories of childhood and delusions of uniqueness which give us a sense of identity, but which serve no purpose other than to keep us going, as our genes require? Dick’s speculative hunt for fake humans cast the Turing test in a new light: not as a proof of the ability of artificial intelligence to “pass for human”, but as a test of humanity itself, which leads to a most severe demotion for those who fail to convince interlocutors that they are really human. All that aside, I revere him for his aphorism: Reality is that which, when you stop believing in it, doesn’t go away.

Here, I intend not to track down and destroy errant replicants, but to champion findings which, even if you don’t believe in them, don’t go away.

My text is the recent paper by Plomin, DeFries, Knopik and Neiderhiser “Top 10 Replicated Findings From Behavioral Genetics. Perspectives on Psychological Science” 2016, Vol. 11(1) 3–23. The deeper background is the major textbook in the field by those same authors 2013 Behavioral genetics (6th ed.). New York, NY: Worth.

By the way, 6 editions should give pause, should it not, to those who just want to jump into the field without doing any of the reading. Below I list, in very abbreviated form, and largely based on the text with a few additions and simplifications, 10 genetic findings which replicate:


1. All psychological traits show significant and substantial genetic influence

For example, a review of the world’s literature on intelligence that included 10,000 pairs of twins showed identical twins to be significantly more similar than fraternal twins (twin correlations of about .85 and .60, respectively), with corroborating results from family and adoption studies, implying significant genetic influence.

For example, for psychopathology a meta-analysis of 14 twin studies of schizophrenia showed monozygotic (MZ) concordances of about 50% and dizygotic (DZ) concordances of about 15%, suggesting significant genetic influence; this finding has been corroborated in more recent studies, as well as in adoption studies.

For personality, scores of twin studies over the decades have shown evidence of significant genetic influence for dozens of traits studied using self-report questionnaires; results have been confirmed in meta-analyses with adoption and family data as well as twin data on 24,000 pairs of twins. Traits such as political beliefs, religiosity, altruism, and food preferences also have shown significant genetic influence. A recent meta-analysis of data drawn from 3,000 publications on nearly 18,000 traits of 15 million twin pairs showed that this finding is not limited to psychological traits.

For general intelligence, heritability estimates are typically about 50% in meta-analyses of older family, twin, and adoption studies as well as newer twin studies. For personality, heritability estimates are usually between 30% and 50%. For example, well-being is a relative newcomer in relation to genetic analyses of personality; a meta-analytic review of 10 studies based on 56,000 individuals yielded a heritability estimate of 36%.

In sum, all traits are genetically influenced.


2. No traits are 100% heritable

Some traits, such as individual differences in height, yield heritability as high as 90%. Behavioural traits are less reliably measured than physical traits such as height, and error of measurement contributes to nonheritable variance. Many have noted that no traits are 100% heritable.

Although this finding might seem obvious and unsurprising, it is crucial because it provides the strongest available evidence for the importance of environmental influence after controlling for genetic influence. Because genetic influence is significant and substantial, one must control for genetic influence when investigating environmental influence. Environmental research using genetically sensitive designs has led to three of the most important discoveries about the way the environment affects behavioural development, presented as Findings 7, 8, and 9.

The environment, broadly defined, has an impact on traits.


3. Heritability is caused by many genes of small effect

If only a few genes were responsible for the heritability of a trait, selected lines would separate after a few generations and would not diverge any further in later generations. In contrast, selection studies of complex traits show a linear response to selection even after dozens of generations of selection, as seen, for example (Fig. 1), in one of the largest and longest selection studies of behaviour that included replicate selected and control lines (DeFries, Gervais, & Thomas, 1978).

Selection effects over 30 generations

It is a pity this figure is not in colour, but the findings are a brilliant example of the breeder’s equation in action (R = h2 S. R is the response to selection, S is the selection differential, and h2 is the narrow-sense heritability.)

The top lines are those mouse strains selected for high activity even in stressful situations, which constitute fearless explorers (non-reactives) while the bottom lines are fearful mice, rooted to the spot in stressful settings (reactives) and shitting frequently. (One of my colleagues, the late Gudrun Sartory, charged with counting the boluses of faeces emitted by such mice, posed a methodological dilemma over a tea break in the Institute of Psychiatry canteen: one terrified mouse had eaten a bolus in panic. Should she count, as required by the test protocol, only the boluses at the end of the experiment, or add the eaten one to the final total?)

Without any form of selection, the middle lines reveal average levels of fear. The difference between the fearless and fearful strains is evident after 7 generations and undeniable after 10 generations. It is selective breeding imposed from outside the population which has caused this massive difference over time, with clear implications for humans under strong selection for any particular heritable characteristic, who might be expected to be very different after 10 generations, say 250 years.

Another overlooked point from selection studies is that genetic effects transmitted from parents to offspring can be due only to additive genetic effects (the independent effects of alleles and loci that “add up”) in contrast to non-additive genetic effects in which the effects of alleles and loci interact. This is important information because it would be difficult to identify specific DNA differences responsible for heritability if genetic effects on behavior were caused by interactions among many loci (epistasis).

In sum, even if you don’t know which genes are involved, by keeping selecting for particular behaviours like intelligence and diligence you can shape the next generations.


4. Phenotypic correlations between psychological traits show significant and substantial genetic mediation

Phenotypic covariance between traits is significantly and substantially caused by genetic covariance, not just environmentally driven covariance. That is to say, taking genetics into account shows that many traits share genetic pathways.

More than 100 twin studies have addressed the key question of co-morbidity in psychopathology (having more than one diagnosed disorder), and this body of research also consistently shows substantial genetic overlap between common disorders in children and in adults. For example, a review of 23 twin studies and 12 family studies confirmed that anxiety and depression are correlated entirely for genetic reasons. In other words, the same genes affect both disorders, meaning that from a genetic perspective they are the same disorder.

The genetic structure of psychopathology does not map neatly onto current diagnostic classifications. Moreover, correlations between personality dimensions and psychopathological diagnoses also are mediated genetically, most notably between neuroticism and depression.

Psychiatry will have to do some re-writing, clinical psychology as well.


5. The heritability of intelligence increases throughout development

This is a strange and counter-intuitive finding: one would expect the effects of learning to accumulate with experience, increasing the strength of the environmental factor, but the opposite is true.

Increasing heritability of intelligence with age

Shared environmental effects, as from family life and school, decrease with age. Good family lives and good schools are not the essential start in life that many people have always imagined, or at least not crucial in societies where family life and schools are reasonably good.


6. Age-to-age stability is mainly due to genetics

Longitudinal genetic studies consistently show that phenotypic correlations from age to age are largely due to genetic stability. In other words, genetic effects contribute to continuity (the same genes affect the trait across age), whereas age-to-age change is primarily the provenance of environmental factors.

For intelligence, similar results have been found, for example, in a meta-analysis of 15 longitudinal studies. This finding creates an apparent paradox: How can the heritability of intelligence increase so substantially throughout development if genetic effects are stable? How can the same genes largely affect intelligence across the life course and yet account for more variance as time goes by? Increasing heritability despite genetic stability implies some contribution from what has been called genetic amplification (Plomin & DeFries, 1985). In other words, genetic nudges early in development are magnified as time goes by, increasing heritability, but the same genetic propensities continue to affect behavior throughout the life course.

This amplification model has recently been supported in a meta-analysis of 11,500 twin and sibling pairs with longitudinal data on intelligence, which showed that a genetic amplification model fit the data better than a model in which new genetic influences arise across time. Genotype/environment correlation seems the most likely explanation, in which small genetic differences are amplified as children select, modify, and create environments correlated with their genetic propensities.


7. Most measures of the “environment” show significant genetic influence

Although it might seem a peculiar thing to do, measures of the environment widely used in psychological science—such as parenting, social support, and life events—can be treated as dependent measures in genetic analyses.

If they are truly measures of the environment, they should not show genetic influence. To the contrary, a review of the first 18 studies in which environmental measures were used as dependent measures in genetically sensitive designs and found evidence for genetic influence for these measures of the environment. Significant genetic influence was found for objective measures such as videotaped observations of parenting as well as self-report measures of parenting, social support, and life events. How can measures of the environment show genetic influence?

The reason appears to be that such measures do not assess the environment independent of the person. As noted earlier, humans select, modify, and create environments correlated with their genetic behavioral propensities such as personality and psychopathology. For example, in studies of twin children, parenting has been found to reflect genetic differences in children’s characteristics such as personality and psychopathology.

In sum, environments are partly genetically-influenced niches.


8. Most associations between environmental measures and psychological traits are significantly mediated genetically

For example, rather than assuming that correlations between parenting and children’s behavior are caused by the environmental effect of parenting on children’s behavior, one should consider the possibility that the correlation is in part due to genetic factors that influence both parenting and children’s behavior. Individual differences in parenting might reflect genetically driven differences in children’s behaviour, or differences in parenting might be due to genetically driven propensities of parents that are inherited directly by their children. For example, for children aged 2 years, the correlation between the Home Observation for Measurement of the Environment was .44 in nonadoptive families, (in which parents shared nature as well as nurture with their offspring), compared with .29 in adoptive families in which parents and offspring were genetically unrelated.

Disentangling genetic and environmental influences on correlations between environmental and behavioral measures is important because 1) if these correlations are mediated genetically, interpretations that assume environmental causation are wrong, with important implications for intervention 2) genetically sensitive designs can identify causal effects of the environment free of genetic confounds 3) genetic mediation of the association between environmental measures and behavioral traits suggests a general way of thinking about how genotypes develop into phenotypes, moving from a passive model of imposed environments to an active model of shaped experiences in which humans select, modify, and create experiences in part based on their genetic propensities.

People to some extent make their own environments.


9. Most environmental effects are not shared by children growing up in the same family

This is an extraordinary finding, and overturns many long-held assumptions. It is reasonable to think that growing up in the same family makes brothers and sisters similar psychologically, which is what developmental theorists from Freud onwards have assumed. However, for most behavioral dimensions and disorders, it is genetics that accounts for similarity among siblings. Although environmental effects have a major impact (see Finding 2), the salient environmental influences do not make siblings growing up in the same family similar. The message is not that family experiences are unimportant but rather that the relevant experiences are specific to each child in the family. This finding was ignored when it was first noted and controversial when it was first highlighted, but it is now widely accepted because it has consistently replicated. The acceptance is so complete that the focus now is on finding any shared environmental influence, for example, for personality and some aspects of childhood psychopathology.

For instance, for antisocial behavior in adolescence, shared environment accounts for about 15% of the total phenotypic variance; however, even here non-shared (unique) environment accounts for more of the variance, about 40% in meta-analyses, although this estimate includes variance due to error of measurement. Academic achievement consistently shows some shared environmental influence, presumably due to the effect of schools, although the effect is surprisingly modest in its magnitude (about 15% for English and 10% for mathematics) given that this result is based on siblings growing up in the same family and being taught in the same school. An interesting developmental exception is that shared environmental influence is found for intelligence up until adolescence and then diminishes as adolescents begin to make their own way in the world, as shown in meta-analyses.

Rather than asking whether a monolithic factor like parental control is primarily responsible for non-shared (unique) effects, it might be necessary to consider many seemingly inconsequential experiences that are tipping points in children’s lives. The gloomy prospect is that these could be idiosyncratic stochastic experiences. However, the basic finding that most environmental effects are not shared by children growing up in the same family remains one of the most far-reaching findings from behavioral genetics. It is important to reiterate that the message is not that family experiences are unimportant, but rather that the salient experiences that affect children’s development are specific to each child in the family, not general to all children in the family.


10. Abnormal is normal

This is an oddly described finding, which simply means that abnormality is the far extreme of a normal behaviour, rarely a discrete entity in its own right.

Quantitative genetic methods suggest that common disorders are the extremes of the same genetic factors responsible for heritability throughout the distribution, although the evidence is indirect and the methods are somewhat abstruse.

Research using the DF method has shown consistently that group heritability is substantial for cognitive disability such as language, mathematical, and general learning disability, as well as for reading disability. An interesting exception involves severe intellectual disability (IQ< 70), which DF extremes analysis suggests is etiologically distinct from the normal distribution of intelligence.

On the basis of common SNPs, it seems safe to hypothesize that most common disorders are at the genetic extreme of the spectrum of normal trait variation. This seems a safe hypothesis because heritability of complex traits and common disorders is caused by many genes of small effect (Finding 3), which implies that together these genetic effects will contribute to a quantitative distribution, as Fisher (1918) assumed, even though each gene is inherited in the discrete manner hypothesized by Mendel (1866).


Here endeth the lesson.

These are not laws, and certainly not commandments, simply findings which are very probably true. Further work will amplify the details. Crucially, we need to understand precisely how many genes of small effect end up having the massive effects we notice in everyday life.

• Category: Science • Tags: Behavior Genetics, Genetics, Human Genetics 

Oscar error

Although I cannot claim to be in the mainstream of contemporary culture, even I have heard of the Oscar error. I should immediately state that I have no specialist knowledge about Oscar ceremonies, because I have never watched one, though I have seen many brief highlights of acceptance speeches (a maudlin art form in their own right), and have no opinion about the actual movies, because I have not seen them. So, this is blank state stuff.

However, procedural errors are a very interesting matter, in that they involve intelligence at two stages. First, a person carrying out a procedure has to think through what they are doing. Second, that person, or preferably others, have to look through the procedures and think about the errors which may arise, and how to avoid them.

The airline industry has done that very well. Plane crashes cause many deaths in one go, which certainly draws public attention. The industry has worked hard to avoid errors because frightened customers are less likely to fly. Most improvements have been technological, in the sense of making instruments and controls easy and intuitive to use, but there is careful screening of pilots (with some glaring exceptions) and standard checklists to overcome forgetting of important matters. There is training to recover from errors and infrequently encountered hazards.

Try putting “Germanwings” in my search bar for some comments on the monitoring of pilots. For an attempt to make sense of the then recent loss of a plane, see:

Surgical teams have been slower to learn, but have now cleaned up their act by following airline industry procedures. All major industries attempt to reduce errors. Motorola led the way in manufacturing, and Toyota and many others all have their systems.

My guide to errors is James Reason “Human Error” 1991.

Just to show how everything links to intelligence and intelligence researchers, that book begins with Spearman (1928) who complained “crammed as psychological writings are, and must needs be, with allusions to errors in an incidental manner, they hardly ever arrive at considering these profoundly, or even systematically”.

James Reason has a good classificatory system, and a set of explanations which link up with well-known psychological findings, namely that despite the capacity to take in many sensory messages, people have limited channel capacity. The multitude of inputs has to get through the bottleneck of working memory, and some inputs never make it, and are lost. Operators also have to remember what they intend to do, and the steps they have to take, the sequence being triggered by the correctly remembered completion of the previous step in the grand plan. In complex cases the grand plan has to be dropped in favour of a new plan, as when engines fail and a plane must find a place to land in the next few minutes.

The Oscar error was an unintentional error, a slip or lapse, probably caused by distraction, maybe because of the operator tweeting pictures from backstage, not part of his key duties. The procedural error was apparently not having a systematic way of cancelling (discarding) an unused envelope. It is a traditional “place-losing” sequence error, with the added piquancy that the “double envelopes” routine is itself intended to be a safety routine. Safety sometimes creates danger. Fixes are easy to suggest: giving the envelopes numbers in sequence, having the name of the prize in very big letters on both sides of the envelope so that announcers know what they are announcing, having the latest discarded envelope showing at the top of a transparent trash can so that the person handing them out can see them, and so on. There are several thousand operators who can suggest improvements.

The fascination for researchers is that each step in an intentional sequence has several consequences, not all of which are easy to predict. As a general rule, failure to predict is an indicator of low ability, but that must be considered in terms of the complexity of the operations being undertaken. One systematic problem is the inability to imagine improbable scenarios until they happen. Incomplete fault trees are legion, and often undetectable on close inspection. If you present a fault tree with sections missing, even skilled operators rarely notice the omissions. In theory, safety systems should catch these errors. James Reason describes each set of safety systems as slices of Emmental cheese intended to stop errors having fatal consequences, until by chance all of the holes in the cheese line up. Bhopal had three systems, none of which operated properly. His analysis of the Chernobyl explosion is fascinating, particularly piquant because it was caused by a badly planned test of a safety system.

In the case of the Oscar ceremony, having the stars come out onstage from two wings rather than one is an obvious procedural hazard. Cutting that out would be a prudent step. In that way you halve the number of envelopes. The Rocket Sled engineers would have spotted anything comparable in the 1950s, and Motorola would have had the stats in their Six Sigma project in 1986.

You might be tempted to say that Chernobyl, Bhopal, plane crashes and industrial accidents are more important than a movie awards ceremony. I could not possibly comment, since I am not among the millions who regard the latter as interesting, but they illustrate an important limitation of human operators. All of us sometimes misperceive reality, and lose our place in a sequence.

I am available for Oscar ceremony interviews next year. For those of you very interested in such matters, I will be wearing an old dinner jacket and a weary expression.



• Category: Ideology • Tags: Academy Awards, Mental Traits 
Smart groups are (simply) groups of smart people.

Group discussion Few things attract more attention in the business world than new ways of making groups work well. As any fool knows, groups are a pain. They argue, dither, drift off course, waste time and resources, and produce loads of rubbish. Worse, all those participants draw salaries, so treasure is wasted. Surely, bosses think, any technique that promises to make groups productive will be better than what they have now: a dysfunctional collection of pointless individuals, wasting their time by rushing off in aimless directions? They reject the absurd notion that one person should do the job, and that the dysfunctional team should be disbanded. Leadership: that is what is required, they proclaim.

So, the poor hapless managers are sent off to Leadership courses, and come back with interesting theories which get nowhere, because the rest of the staff have not been sent off to Followership courses. Leaders always require followers. While everyone loves Leadership courses, being recommended for a Followership course would probably cause great offence. A pity. It is fatal to any enterprise when people can neither command nor obey.

While the supposed leaders have been away at an expensive hotel ,the remaining staff have sorted out the problem to their own satisfaction, sometimes with good effect, and most often by cobbling together a patch to protect their own interests. So, it is with grim satisfaction that one learns of Group Performance Enhancement Theory No 347, namely that people working in groups on complex problems:

“show a strong general-ability or IQ factor, with significant differences between groups on this factor. Surprisingly, group-IQ, or “collective intelligence” is not strongly correlated with the average or maximum individual intelligence of group members but is correlated with the average social sensitivity of group members, the equality in distribution of conversational turn-taking, and the proportion of females in the group.

So, if I have understood this correctly, the individual IQs do not matter too much, so long as the group is socially sensitive, takes turns in speaking, and includes women. Personally, having heard this proposal I would have thought it unlikely. Bates and Gupta, however, are truer to the spirit of empiricism, and embody Carl Sagan’s injunction (my summary) that scientists should be kind to hypotheses and tough on proofs.

What is more, since the original study by Woolley et al in 2010 was cited over 700 times, this finding is likely to be the cornerstone of a myriad of training courses, as participants attempt to be sensitive, willing to wait their turn, and womanly. Bates and Gupta have bothered to find out if collective intelligence (group IQ) actually exists. They point out:

For some time, it has been known that work-groups whose team-members have higher IQ out-perform teams of less-able members (Devine & Philips, 2001). Against this background, Woolley et al. (2010) asked whether groups themselves exhibit a general-factor of intelligence, if this might be distinct from individual IQ, and, if so, what the origins of such a collective intelligence might be.

To assess group-IQ, subjects were allocated to small groups and performed tasks including brainstorming, matrix reasoning, moral reasoning, planning a shopping trip, and collaborative text editing. They did all this in 3 studies, so there is a lot of detail in the paper about the findings from their individual studies, and further work on the combined results, usually studies 2 and 3. Woolley et al. (2010) came to the conclusions described above, namely that it is the collective IQ which develops (due to sensitivity, turn taking in conversation, and women members) which is important, and not the IQ of the members of the group. Bates and Gupta sum up the findings of their replication thus:

What allows groups to behave intelligently? One suggestion is that groups exhibit a collective intelligence accounted for by number of women in the group, turn-taking and emotional empathizing, with group-IQ being only weakly-linked to individual IQ (Woolley, Chabris, Pentland, Hashmi, & Malone, 2010). Here we report tests of this model across three studies with 312 people. Contrary to prediction, individual IQ accounted for around 80% of group-IQ differences. Hypotheses that group-IQ increases with number of women in the group and with turn-taking were not supported. Reading the mind in the eyes (RME) performance was associated with individual IQ, and, in one study, with group-IQ factor scores. However, a well-fitting structural model combining data from studies 2 and 3 indicated that RME exerted no influence on the group-IQ latent factor (instead having a modest impact on a single group test). The experiments instead showed that higher individual IQ enhances group performance such that individual IQ determined 100% of latent group-IQ. Implications for future work on group-based achievement are examined.

After doing their 3 studies and re-analysing the results, they conclude: Smart groups are (simply) groups of smart people. By contrast, we found little to no evidence for two proposed causes of group-IQ: numbers of women in the group and turn-taking, and found evidence for a weak and specific impact of RME on one group task, but not on latent group-IQ.

Here is the relationship between the IQs of the individuals in the group, and the resultant group intelligence. If particular group IQs develop, then the group IQs will differ from the mere sum of the individual IQs. In fact, there is a close match.

Collective and individual IQ

Here are all their results summarised in a best fitting model.

Collective IQ depends on individual IQ

Individual’s IQs lead to the group average IQ, which explains the performance the group achieves on all of the tasks. On one task, Missing letters, the Mind in the Eyes task makes a small additional contribution. They add:

The present findings cast important doubt on any policy-style conclusions regarding gender composition changes cast as raising cognitive-efficiency.

Their findings should not be interpreted as meaning that groups are useless. On the contrary, given that the management of clever people is so important for success, care must be taken to let the best thinkers concentrate on the hardest problems. Also, it implies that organizations should pay close attention to the intelligence of their staff members, and very probably to pay more attention to the opinions of their brighter workers.

And there the silly story would end, but there is a sting in the tail. Not only was the original paper cited 700 times, but it was cited without the benefit of a replication. All researchers may be tempted to do that, particularly when a study buttresses a position they like. However, since so many psychological studies fail to replicate, there is now general agreement that replications should be given as much attention as the original claims. So, how did reviewers respond to Bates and Guptas’s replication? With considerable reservations, it appears.

While every paper has to run the gauntlet of reviewer criticism, this one seems to have experienced unusual opposition. In their discussion section the authors reply to the objections raised by unnamed reviewers. A reviewer complained about lack of statistical power, but the main analysis of studies 2 and 3 had a power of 95%. This is a technical discussion, but I think the reviewer got it wrong.

A reviewer judged that the replication was not a replication. Bates and Gupta used the same IQ tests, the same test of empathy, and those tests of successful team work which had best shown the effects which Woolley et al. claimed in the original research. Looks like a replication to me.

Turn-taking was measured by a simpler technique in the replication, but turn-taking was not shown to be independently predictive of group IQ, rendering the point moot.

An anonymous reviewer suggested that (paraphrasing) there clearly must be an unidentified moderator which accounts for why individual IQ and collective intelligence correlated so strongly. Readers should evaluate this claim for themselves. It is far from clear to us that an unidentified moderator “must” exist.

Bates and Gupta were polite, but they could have responded “You show us why you think there has to be a moderator. Evidence, please”.

A friend of the authors, speaking to me in a dark car park on condition of reviewer-type anonymity, said:

The back story is that this paper went through 4 revisions, in which one reviewer every time demanded 10, 20, or even 38 new changes, none of which involved a single new analysis. They demanded that Bates and Gupta remove study 2, remove variables, include a statement that they had not done a replication, and conclude that this area is vigorous and needs more research. They claimed the work was sloppy, error-filled, and so under-powered no one should publish it. They suggested that no peer-reviewed journal would ever publish such awful work. So, if you think science is an efficient hunt for the truth…Think again.

The impression I get is that the reviewers were being unreasonable, and even obstructive.

You might like to look at this link:

All this further silliness aside, in what I consider to be one of the most important findings about team work, the authors identify a crucial result:

It is interesting also that groups did not perform better than individuals – a genuine group-IQ might be expected to enable problem solving to scale linearly (or better) with number of subjects. In group-IQ tasks, coordination costs appear to prevent group problem-solving from rising even to the level of a single individual’s ability. This implicates not only unsolved coordination problems, which are well-known barriers to scale (Simon, 1997) but also reiterates the finding that the individual problem-solver remains the critical reservoir of creativity and novel problem solution (Shockley, 1957).

So, if you want a problem solved, don’t form a team. Find the brightest person and let them work on it. Placing them in a team will, on average, reduce their productivity. My advice would be: never form a team if there is one person who can sort out the problem.

As regards team work and collective intelligence, another idea bites the dust, at least until a new hypothesis comes along, claiming you can boost team productivity by a training in…(insert something warm and friendly).

No teams were assembled to write this post.

• Category: Science • Tags: group intelligence, IQ, team performance 

Leonard Nimoy as Mr Spock in Star Trek. Photograph: Moviestore Collect

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations. Which is more probable?
1. Linda is a bank teller.
2. Linda is a bank teller and is active in the feminist movement.

Personally, after reading the above description, I have Linda in my mind’s eye, and I can just see her lecturing me on what sort of yoghurt I should eat. If I ever met her, I would not dream of admitting that I drive a diesel car, and that I have very recently taken up sketching nude women. Of course she is a feminist, and against nuclear weapons! That is obvious. (Actually, if Linda is very attractive, it might be worth my while telling her about my book against nuclear war).

“Linda” is the tricky question Kahneman and Tversky made famous. They implied that people who chose answer 2 were being irrational, because, wait for it, it is more likely from a statistical point of view that Linda is a bank teller (answer 1) than that she is a bank teller with a particular political interest (answer 2). This is because there will be at least some bank tellers who are not feminists, and even if there is only one such bank teller, then the category “bank teller and also feminist” will be smaller than the category “bank teller”. So, it is more likely that she is just a bank teller.

However, the introductory remarks have lead you into getting the sucker punch. The woman is SINGLE for God’s sake, despite being 31 years of age. Some problem there. Despite being a woman, she is OUTSPOKEN and VERY BRIGHT. She studied PHILOSOPHY which I can testify puts you on a hiding to nothing. She was DEEPLY CONCERNED with issues of DISCRIMINATION and SOCIAL JUSTICE. ANTI-NUCLEAR completes the picture. Answer 2 is the better match with the female of this species.

For many years some people have been asserting that tests of rationality show that IQ tests leave out an important aspect of mental ability. If you are clever, but screw up on the Linda Question, then that shows that you lack rationality. Like most things, this is an old debate, best presented by Peter Cathcart Wason, who started this horse running with his four card logic problem in 1966. I heard him lecture on it at The National Hospital, Queen Square, in 1968 or thereabouts, and he demurred when the neuro-surgeon introducing him said that he thought the problem “somehow unfair”. That comment caught the essence of the matter very well.

The other interpretation is that, far from being a test of rationality, whatever that is, the Linda Question is tricky, and teaches you more about the specific question form than about general human thinking processes. Question forms are interesting, and should be studied, particularly by those writing instruction manuals, government advice brochures, and examination questions. Confusing people is easy. Writing clearly and honestly is more difficult.

I have explained all this before, and will probably keep explaining it for ever, because many people, discouraged by clear evidence of their palpably limited intellects, would like a Get Out of Jail card from Multiple Intelligence, Emotional Intelligence, Practical Intelligence and now, Rational Intelligence.

As you will have seen if you read the second list, I wished the authors good luck in making their test, but was implying it would be difficult.

Stanovich, West and Toplak have now published their book: “The Rationality Quotient: Towards a test of rational thinking”. This is a “Towards” book, and we should not be too impatient, because scholarship takes time. However, it is a bit frustrating. The book gives an erudite account of the issues, but then only selected gems from the relevant work, much of it unpublished. What happened to the old-style test manuals? They had short introductions, a much longer section on standardization samples and general procedures, full instructions about how to administer and score each test, and then correlation matrixes, some factor analyses, and standard score conversion tables. You knew where you were with these manuals. You had to read them to understand what you were doing, and had to hang on to reliability and validity measures for dear life: without those the test was useless. Presumably, we will have to wait for that test manual. Daniel Kahneman, however has seen enough to aver that “it makes a compelling case for measuring rationality independently of intelligence”. Should we be compelled to that conclusion?

There is no a priori reason why a new test of rationality, or practical intelligence, or emotional intelligence or multiple intelligence should not supplant the current range of psychometric tests developed over the last 110 years. Improvements happen. All the new test has to show is that it is a better predictor of real life outcomes than the former test. In an instant, the old test is toast.

Why do the developers of CART, heavily trailed as reaching the reasoning zones that ordinary psychometric tests cannot reach, not bother with validity tests? I pondered this and decided that, prior to reading it, I would sketch out what validity tests would be required. I needed a real life measure of reason, and a strong motive for people to exercise their reason in attaining their goal. Finally, the answer struck me: most people work for a living, and most reasonable people save some money for long retirement. Would tests of rationality, I asked myself, be better predictors of investment strategies and outcomes than ordinary tests of intelligence?

No sooner do I pose the question than I find that Stuart Ritchie has already reviewed the book, and found out that the authors have not bothered with validity tests.

So, I no longer have to review the book. Ritchie has done the job, calmly, kindly, and lethally. He has lanced the pretensions of the “rationality tests are better than intelligence tests” by showing they have not yet provided any validity data, and in terms of their association with intelligence tests, they correlate 0.7 Here is an illustrative table.
Rationality and IQ

Naturally, the individual subtests vary considerably in their correlations with intelligence, but the final test result is closely linked with IQ. Indeed, from a psychometric viewpoint it is no more than a long-winded and very cumbersome intelligence subtest, and so it will remain, until validity data proves otherwise. However, these correlations are instructive, so make a mental note of the ones that most rely on intelligence, and then compare with my comments below.

Here are a few reflections as a post-script to Ritchie. If Rationality is a thing, it must hang together. Tests of rationality should correlate with each other because they have rationality in common. As a rule of thumb, subtest correlations should be better than 0.6, ideally 0.7 and above. Absent such correlations, the subtests would be no more than a hodge-podge of curiosities.


Rationality subtest correlations with total

Furthermore, inspection of the correlations between the subtests shows that many of the subtests are apparently not testing the same mental skill of rationality. Correlations of 0.28 hardly suggest a common factor. I think these are disparate tests, corralled under a one-size-fits-all banner. Wechsler subtests look pristine by comparison. From a psychometric point of view the following subtests (ordered by correlations including, and then excluding, the subtest in the total score) seem promising:

1 Probabilistic reasoning .78 .71
2 Scientific reasoning .78 .70
3 Reflection versus Intuition .77 .71
14 Financial literacy .72 .65
4 Syllogistic reasoning .68 .62
13 Probabilistic numeracy .67 .62

Is it just me, or do these have an IQ-like look to them? In fact, the ones that correlate which each other are ones which require intelligence as shown in the correlations with cognitive ability listed above. This is something of a crisis for any test of rationality. If they pick the best 6 sub-tests and drop all the others, they could get the whole test down to manageable proportions and quick enough to use. Currently, the full form is far too long, but this is part of the test development process. Neither subjects or test givers like long tests. There are many quick IQ tests against which a rationality test will have to compete. However, how much Rationality will reside in such a test? It will be just another IQ test. To stick true to their own mission they should reject the list above and concentrate on those tests which do not correlate with intelligence. This will be the pure rationality they seek. The fact that those tests don’t correlate with each other is a problem they will have to solve.

Validity measures must be proffered for this new test, or the whole thing will be no more than a burst bubble, a party balloon that popped.

I think that Kahneman has been premature in concluding that we should measure rationality independently of intelligence. Currently it is no more than a cumbersome subtest, with no demonstrated advantages.

What I cannot refute is that many show a deep desire to supplant tests of intelligence. Far from doing so, this “Towards” book has inadvertently done a good job of showing that Rationality is very probably not separate from Intelligence, and that the tests of a presumed common factor of rationality are a very mixed bunch. I suspect they are mostly a collection of tricky questions organized into general types. Refined down to the best subtests, and further refined down to the most discriminating items, it might be possible to construct a test which clinicians and researchers will use. That remains to be demonstrated, and depends validity measures. It would be good to see if a Rationality Quotient was a better predictor of long-term investment performance than an IQ test.

Grant proposal, someone?

• Category: Science • Tags: Mental Traits, Rationality 
Add fertilizer and yields are boosted, up to a plateau; ignore the quality of the seed and yields slowly decline.

dying plants Everyone knows about the Flynn Effect, but very few about the Woodley Effect.
When Woodley was working on his paper in 2013 “Were the Victorians cleverer than us? The decline in general intelligence estimated from a meta-analysis of the slowing of simple reaction time” I wrote to Charles Murray about his findings, and in his reply he asked: “So when are we going to get a reconciliation of the Flynn Effect and the Woodley Effect?” Thus, Murray has named both the apparent environmental rise in intelligence, and the possible fall in underlying genetic intelligence.

By analogy with agriculture, we could say that the Flynn Effect is about adding fertilizer to the soil, whereas the Woodley Effect is about noting the genetic quality of the plants. In my last post I described the current situation thus: The Flynn Effect co-exists with the Woodley Effect. Since roughly 1870 the Flynn Effect has been stronger, at an apparent 3 points per decade. The Woodley effect is weaker, at very roughly 1 point per decade. Think of Flynn as the soil fertilizer effect and Woodley as the plant genetics effect. The fertilizer effect seems to be fading away in rich countries, while continuing in poor countries, though not as fast as one would desire. The genetic effect seems to show a persistent gradual fall in underlying ability.

Woodley’s claim is based on a set of papers written since 2013, which have been recently reviewed by Sarraf.

The review is unusual, to say the least. It is rare to read so positive a judgment on a young researcher’s work, and it is extraordinary that one researcher has changed the debate about ability levels across generations, and all this in a few years since starting publishing in psychology.

The table in that review which summarizes the main findings is shown below. As you can see, the range of effects is very variable, so my rough estimate of 1 point per decade is a stab at calculating a median. It is certainly less than the Flynn Effect in the 20th Century, though it may now be part of the reason for the falling of that effect, now often referred to as a “negative Flynn effect”.

Woodley effect Sharraf

You can now see that calculating the rate of decline is somewhat difficult. Perhaps a median would be “less than 1 per decade”. The time spans vary, the measures also, though the latter variance is an advantage, in that it suggests a general underlying cause. However, the range of estimated decline is very large, from 0 to 4.8 per decade.

Here are the findings which I have arranged by generational decline (taken as 25 years).

  • Colour acuity, over 20 years (0.8 generation) 3.5 drop/decade.
  • 3D rotation ability, over 37 years (1.5 generations) 4.8 drop/decade.
  • Reaction times, females only, over 40 years (1.6 generations) 1.8 drop/decade.
  • Working memory, over 85 years (3.4 generations) 0.16 drop/decade.
  • Reaction times, over 120 years (4.8 generations) 0.57-1.21 drop/decade.
  • Fluctuating asymmetry, over 160 years (6.4 generations) 0.16 drop/decade.

Either the measures are considerably different, and do not tap the same underlying loss of mental ability, or the drop is unlikely to be caused by dysgenic decrements from one generation to another. Bar massive dying out of populations, changes do not come about so fast from one generation to the next. The drops in ability are real, but the reason for the falls are less clear. Gathering more data sets would probably clarify the picture, and there is certainly cause to argue that on various real measures there have been drops in ability. Whether this is dysgenics or some other insidious cause is not yet clear to me.

Sarraf ends on a glowing note:

Ultimately, I cannot give “Historical variability in heritable general intelligence” a higher recommendation. Not since The Bell Curve (Herrnstein &Murray, 1994) has a single work offered such immense psychometric revelations about advanced human societies and their pasts and futures.

My view is that whereas formerly the debate was only about the apparent rise in ability, discussions are now about the co-occurrence of two trends: the slowing down of the environmental gains and the apparent loss of genetic quality. In the way that James Flynn identified an environmental/cultural effect, Michael Woodley has identified a possible genetic effect, and certainly shown that on some measures we are doing less well than our ancestors.

How will they be reconciled? Time will tell, but here is a prediction. I think that the Flynn effect will fade in wealthy countries, persist with fading effect in poor countries, and that the Woodley effect will continue, though I do not know the cause of it.

• Category: Science • Tags: Flynn Effect, IQ, Woodley Effect 

It is good that people are discussing IQ. Fred Reed’s post has drawn many comments, too many for me to answer individually. Here I outline the main heads of his argument as I see them, and some of the relevant research.

My summary of Reed’s post is:

Intelligence is important; intelligence research is important and can influence social policy; American blacks, the Irish, and Mexicans have similar IQs but different outcomes; IQ scores for some countries have been revised considerably, suggesting that intelligence measures are unreliable; Maya Indians had cultural achievements out of all proportion to the low IQs of the current inhabitants; current research shows European intelligence both falling and rising, the latter because of the Flynn Effect, and this suggests the measures are unreliable; the ancient Greek thinkers were very bright, and not dull as the Flynn Effect might imply; the IQ of India cannot be 81 because of India’s cultural achievements; there is no visible difference in intelligence between Mexicans and Americans, nor also with the inhabitants of Taiwan, Vietnam, or Thailand; and what mean IQ is thought necessary to run the infrastructure of modernity?


The first topic to cover is correlation. Correlations are best understood by looking at scatterplots. Any correlation which is less than unity will have discrepant data points scattered along the trend line. Some countries will be outliers for different reasons, all of them worth debating. For example, the usual link between IQ and GDP is altered by two main artefacts: oil and tourism. However, there are other reasons, and it is certainly worth following up all outliers, and putting forward testable hypotheses about why this is so. Of course, these hypotheses need to be tested on the whole data set. Even when the correlation is strong, say 0.8 there will still be discrepant cases (large residuals, in statistical jargon).

A discrepant data point does not destroy a general correlation. If there are many discrepant results the correlation is lowered. If all results are discrepant there is no correlation to discuss. Individual instances do not refute general findings. A test of intelligence which is an excellent predictor of later success in life will not always identify the most successful individual. There will always be exceptions to be pointed to. Rindermann is a good person to read on the relevant research between country IQ and national achievements.


The Flynn Effect co-exists with the Woodley Effect. Since roughly 1870 the Flynn Effect has been stronger, at an apparent 3 points per decade. The Woodley effect is weaker, at very roughly 1 point per decade. Think of Flynn as the soil fertilizer effect and Woodley as the plant genetics effect. The fertilizer effect seems to be fading away in rich countries, while continuing in poor countries, though not as fast as one would desire. The genetic effect seems to show a persistent gradual fall in underlying ability. Intelligence tests are good at identifying skills with high predictive value for life success, but less good at doing historical comparisons, unless one concentrates on specific subtests. IQ percentile ranks hold up very well over six decades. There is much research on this issue. Jim Flynn works with many of the new researchers on the topic, like Elijah Armstrong. It is a somewhat technical field, but very interesting.

Country totals may appear to change, but that is to be expected if the initial samples were few and not properly representative. Well organized countries provide better data than less organized ones. As more data comes in the results should get to be more accurate. For that reason the whole Lynn database has been made public, and is being improved and extended. There is more work to be done, particularly adding in the cognitive estimates derived from maths and science examination results from international tests.

For the purposes of this discussion, it should be noted that the Lynn database for Mexico references only 3 studies, all of children, in the 6 to 13 year range, which you can see on the National IQ database, ranging from 80 to 88, for an overall mean IQ of 85. Adult data and more data would be better. However, a recent analysis of PISA, TIMSS and PIRLS data (1995 to 2012, N 93 nations) comes up with an IQ derived from those results of 88. The similarly derived IQ for the USA is 99.6.

Cognitive capitalism and high ability stem

Historical comparisons over several centuries are harder to carry out, but not impossible. Rindermann and I put in measures of historical cultural ancestors on two time spans: Nobels for the last century, and eminent scientists since 800 BC (the Ancient Greek effect) and showed that they both made a contribution to modern day economies. However, Greece is no longer the centre of the intellectual world, nor are the Mayas. Their accomplishments were real enough in their time. Their best thinkers are still rightly revered, but a nation’s current IQ is not always a good guide to the abilities of very distant ancestors. If populations move of their own volition or are displaced by new entrants, the general intellectual level can change. On the other hand, if selection on a settled population is hard enough then intellectual levels can rise in 8 to 16 generations. That is another interesting story.

The Indian mean IQ of 80 is based on 26 studies, so is well covered. Nevertheless, there is variability according to which province one measures, even more different than the States of the United States. The caste system creates differences. So does the rate of cousin marriage.


Naturally, you can have some bright people from all countries: is it the proportions which differ. Any big deviations from what you would expect from the country bell curve calls into question the stated average for that country.

“No visible difference in intelligence between Mexicans and Americans, nor also with the inhabitants of Taiwan, Vietnam, or Thailand.” Cannot really comment on that, except to say that in social interaction it is not always either possible or desirable to make intelligence estimates. More relevant is to look at technical innovation rates, patents, science publications and the like. However, it would be a valid point if there were no differences in the achievements of those countries and the functioning of their societies. If there were no differences on the above measures, then the associations between mental ability and social outcomes would be weakened, and eventually disconfirmed. However, the general link between national IQs and economic outcomes holds up pretty well.

What mean IQ is thought necessary to run the infrastructure of modernity?

This interesting question has been much discussed. Smart fraction research suggests that the impact of the brightest persons in a national economy has a disproportionately positive effect on GDP. Rindermann and I have argued, following others, that the brightest 5% of every country make the greatest contribution by far, though of course many others of lower ability are required to implement the discoveries and strategies of the brightest. There have been two supportive replications.

On this basis you might say that countries depend on those with IQs of 120 and above. These are the people who can follow “college format” education in which they read provided references and work out the implications for themselves, guided by tutor and test feedback. The USA can rely on 8% of their people to do such work, Mexico 2%. If countries can find such people, retain them, and deploy them properly, with a good pyramid of helpers below, then the country concerned has a good prospect of doing well. However, given global competition, countries need many people of IQ 130+ to really prosper, and such people tend to emigrate to the strongest economies, where they will earn most, so less able countries are often denuded of their brightest citizens. The USA can rely on 2% of their population to do such work, Mexico 0.3%.

However, a rule of thumb would be helpful in answering this, and the initial guesstimate was that a national IQ of 93 was required for a reasonable standard of living. I certainly agree that if the overall country data set shows no difference between countries of different intelligence levels, then the intelligence levels are called into question.

As economies globalize, the figure required for innovation and flourishing economies is probably being pushed upwards. At the same time, products are coming out which do many necessary things without requiring much intelligence from users. Mobile phones can perform functions which previously required high ability programing skills. Now, all users have to be able to do is point with their finger. Cars used to be complicated, and require careful maintenance. Now they are more reliable (though harder to service without computer guidance). Cash registers do everything based on pictograms, so a society can function to some extent on the problem solving of others. Good news all round.

Globalization may result in innovative countries being far richer than the countries which don’t innovate but just use the inventions, in the way that most of the world flies on wide body jets made in the USA and Europe. Skyscrapers were an innovation once, and are now commonplace. Nonetheless, the innovators will be the first to get the benefits of modernity, and are likely to retain most of the profits.

• Category: Science • Tags: IQ, Smart Fraction 
James Thompson
About James Thompson

James Thompson has lectured in Psychology at the University of London all his working life. His first publication and conference presentation was a critique of Jensen’s 1969 paper, with Arthur Jensen in the audience. He also taught Arthur how to use an English public telephone. Many topics have taken up his attention since then, but mostly he comments on intelligence research.