Now that we have some British politicians talking about IQ it seems the right time to rush out a summary I was slowly preparing about the lives and achievements of different intelligence bands. Please accept this as a general overview, subject to revision, to which more illustrative details and precise boundaries will be added at a later date.
These are the least able 5% of the population. In a town of 10,000 persons these would constitute 500 citizens. Learning is slow, so all intellectual achievements take a fair bit of time. Since all lifespans are finite, and for this group lifespans are shorter than average, many skills are effectively out of reach because it is very unlikely that they will ever be learnt. Of course, some learning always takes place, because everyone can learn, but in their case the pace must be slow, the materials simple, and the steps carefully supervised.
Lifespans are more than 21% shorter than average, and they are more than 50% more likely to be suffering psychological difficulties than average. They are most at risk of all health problems, and all the problems of life.
These people are “high risk” because they make unforced errors and because they are at risk of being exploited by the unscrupulous. They are less likely to follow rules (perhaps they cannot see the point of them) or to delay gratification, and more often than average to wind up in trouble. They have high levels of credulity, tend to believe in god and magic and coincidence and miracles. Vocabularies are relatively mall, not much above the functional basics of the language. As a rule of thumb, if you understand the 3000 most frequent English words then you will understand 95% of the words in common use. If you understand 5000 words (and their close variants) you get 99.9% word coverage in ordinary language. Computations are restricted to simple operations, mostly addition and subtraction.
They can sign their name and add up the total of bank deposit entries. They can do basic concrete tasks. In terms of reading and entertainments they like stories, picture magazines, music with strong melodies and rhythms, and broad comedy. (Later we can get into the details about what entertainments and materials are favoured). Employment opportunities, which would have been plentiful in simpler agrarian societies, are now far more limited, tenuous, and precarious. Modern life has become very demanding, and simple physical labour no longer adds much value. Their wages will be low, and in kinder and wealthier societies they are likely to be receiving social benefits. The armed services will not recruit them. They have frequent periods without paid work. They will have no effective savings.
There is little about their appearance which would indicate limited intellectual power, and their social conversation is usually in line with basic social niceties. It would take more somewhat more extensive conversations to reveal shortcomings. They can use mobile phones and drive cars, though they would have difficulty with the driving theory exam. They would also crash about three times more often than average. They are very recognisably our cousins, much more like us than not. In IQ terms they are 75 and below.
These are the next 20% of the population in terms of ability. They would be 2,000 citizens in the town of 10,000 inhabitants. Learning is somewhat faster, and achievements are of better quality. Learning varies from the slow pace, simple materials and careful supervision already mentioned previously, to very explicit, hands-on training. They tend to credulity, belief in god and superstition. They can locate the intersection of two streets on a map, identify two features in a newspaper sports story, perhaps calculate the total cost of purchases listed in a catalogue, and draw inferences from two identifiable facts and deal with some distractors.
Vocabularies are somewhat larger, computation includes some multiplication and division. In terms of reading they will enjoy a little more depth in terms of content. Employment opportunities include simple assembly and packaging tasks, food preparation, assistant roles in caring professions. They can use some checklists, and procedural guides. The armed services will probably not recruit them, because many of them will take too long to train.
They have a 21% lower survival up to age 76 (Whalley&Deary 2001). They have about a 50% greater risk of hospitalization for schizophrenia, mood disorder, and alcohol-related disorders (Gale et al. 2010) and for personality disorders (Moran et al. 2009) with more self-reported psychological distress (Gale et al. 2009) and with a greater risk of vascular dementia (McGurn et al. 2008).
They will probably have fast lifestyles, with restricted planning and savings. They have more accidents than average, probably twice as many motor vehicle accidents than average. In IQ terms they are between 75 and 90.
These are the middle 50% of the population. They are the “average” the “man in street” the person with “common sense”. By definition, this is what most people are like. In our town of 10,000 they would constitute a massive 5,000 persons. The town would be built round them, their abilities, their needs, and their frailties. In the way that clothes are mass produced for average sizes and fashions, the town would be made to their taste. The money would follow them. Films, TV, books, magazines, and newspapers are written for them.
Learning is mostly mastery learning, hands on. The brighter ones learn from written materials plus experience. They can deal with tasks which require the integration of multiple pieces of information from one or more documents, which themselves may be complex and contain much irrelevant information. However, the matches they are asked to search for tend to be literal, and the correct information in the test material is not located near incorrect material, where it would be too confusing.
They are almost always able to calculate the total costs of purchases from an order form; write a brief letter explaining an error made on a credit card bill; and using a calculator, work out what the discount would be on a bill if paid within 10 days; enter information into a car maintenance record; and perhaps be able to state in writing the argument made in lengthy newspaper article. Vocabularies are in the 17,000 to 21,000 range, with older people in the upper part of the range.
They may believe in god, have some superstitions, be fooled by some coincidences, have difficulty in calculating some odds, but are usually adept at using rules of thumb and avoiding confidence tricks and deceptions. They know that magic depends on tricks, even if they cannot explain them. Their understanding of science will be basic and subject to omissions. They can catch out brighter people in errors, and tend to be pragmatic, with little theory. However, they may believe that day and night are due to the earth going round the sun.
They occupy the middle range occupations, in what used to be clerical trades, and sales jobs of all descriptions. Likely jobs are Police officer, nurse, trainer, and when the job was still available in the economy, machinist. They will delay gratification to some extent, and have some savings. Incredibly, in modern welfare states they would only just be net contributors in tax terms, but would mostly get benefits in almost equal proportion to their tax contributions.
These are the fortunate next 20% of the population. Prospects look better. Learning can now take place in the college format, with lectures and reading lists and set work, though this needs to be well structured and frequently tested. In the brighter part of the range students will gather and infer their own information. They can deal with tasks which require more inferences, multiple-feature matches, integration and synthesis from complex passages or documents, and the use of multiple sequential operations. They could use a bus schedule to determine the appropriate bus for a given set of circumstances; using an eligibility pamphlet, they are able to calculate the yearly amount a couple would receive in basic supplementary security income; and perhaps be able to use a table comparing credit cards to identify the two categories used and to write down two differences between them. Vocabularies are very roughly in the 20,000 to 30,000 range, depending on age.
Occupations like manager, teacher and accountant are achieved. They would be net contributors to modern welfare states, probably equivalent to supporting an extra household, and very probably have some savings of their own. Motor vehicle accidents are at the average rate. In IQ terms they are between 110 and 125.
These are the top 5%. If you are fortunate enough to be in this category, the world is your oyster, unless you blow it by getting drunk, or by imaging that you are so bright that no further work is required, or you go off the rails into being some sort of clever fool, due to some personality difficulty.
Learning will be based on gathering and inferring own information. There may be lectures, but these are optional, with less frequent feedback on results, and more autonomy in learning. Learners are expected to search for faults in what they are taught.
They can deal with tasks which require the application of specialised background knowledge, dis-embedding the features of a problem from a text, and drawing high-level inferences from highly complex text with multiple distractors. They can almost certainly do the previous credit card comparison task; they can summarise from a given text two ways in which lawyers may challenge prospective jurors; and, using a calculator, determine the total cost of carpet to cover a room, given the dimensions of the room and the cost per square yard of carpeting. (There you are, at the apotheosis of intellect. You can challenge a juror and carpet a room). Their occupations will include the professions, the sciences and, with experience and application, the top posts in business and government. Entertainments will include most artistic and literary endevours, and theories will be seen as interesting in themselves. Vocabularies are in the 30,000 to 42,000 range, which is probably as high as you can go without using lots of technical terms. In modern welfare states they would be high net contributors, very probably supporting two or even three households in addition to their own, and have property and savings. In IQ terms they are 125 and above.
And that, dear folks, is it. In a representative sample of people there is a fivefold difference in learning speed, and in intellectual power. Five tribes of humanity are all you need know about. These are the facts, when you come to brass tacks, with which all civilizations must grapple, making whatever choices are required to deal with these natural differences. You can let wages find their own level, or regulate them, or tax them and distribute benefits. If you direct the brightest to the hardest tasks you will solve problems quickly. If you prevent them from doing those tasks progress will be slower. Societies sometimes trust people bright people, sometimes resent and ignore them. Genocides are frequently targeted on them, particularly because they are minorities who generate wealth and exercise social power and influence, and have prestige.
Now that most people have gone away to read lighter material, we can get to the strong stuff, offered to you in a discreet brown paper envelope. Readers of this blog will know that the top 5% doesn’t really amount to much. For example (and now we can do big numbers, being the clever sort of persons we are) being in the top 5% means that in 10,000 persons you would have to share this accolade with 500 other people. Hardly an exclusive club. Some of them would have odd ideas and a thoroughly improper understanding of moderately complicated concepts. Some of them will fail to understand sampling theory, simple statistics, structured equation modelling and factor analysis for a start, and many of them will be subject to foolish delusions and be mired down with considerable ignorance. It was said of an Oxbridge professor that he was overheard chastising his ten year old son thus: “No, no, no, my child! You have totally misunderstood the Medieval Papacy”. People can be a disappointment.
We must draw some distinctions so as to refine this top 5% lump of common or garden intellects into more closely graded achievements. Therefore, within the top 5% we can find two smaller categories. The final category has quite a range to it, if observed closely, but 7 is as far as most of us can count.
Bright the top 1% (100 in 10,000) They are the upper half of the brightest students at the most prestigious universities. They get better degrees, solve more problems, and gain the respect of those for whom the same tasks take lots of time to complete. They are more likely to get doctorates in hard subjects, more likely to publish, more likely to obtain patents and to own businesses.
Vocabularies are in the 35,000 to 42,000 range and most intellectual tasks are within their grasp, although they have many techniques to learn, particularly in maths and science. However, one should not get too precious about being “bright”. The United Kingdom has 650,000 such persons, most of them walking about unsupervised. In IQ terms they are 135. You can call anyone above IQ 130 the Two Sigmas, because they are two standard deviations above the mean.
Eminent (or Scary Bright) the top 0.01% (1 in 10,000) There would be one such person in our town. The town’s progress might depend on whether they are able to contribute their ideas and see them implemented. More likely, they will leave town and search out other eminent people just for the fun of exchanging ideas. Their vocabularies will be above 40,000 words. They are unlikely to believe in gods or superstitions, and can calculate coincidences. (Dick Feynman used to begin his lectures by saying: “As I parked my car today I noticed that the licence plate of the car in front of me was 79346229. What’s the chance of that?”). They may be seen as unconventional, and can be difficult to understand. In IQ terms they are 155. Call them the Three Sigmas.
When such eminent intellects leave town, they soon learn that they are not that bright. After all, even the United Kingdom has 6,500 of them, and they soon work out which the really bright ones are. So, for really interesting minds, we are looking at those who, in open competition, tested on very hard subjects, can show other scary bright people that they are closer to 1 in a million. In IQ terms this would be 160, but it would be simpler to say that they are well above conventional testing limits. Call them the Four Sigmas.
Think of Bertrand Russell going up to Cambridge University and finding very few intelligent people there, but later observing that every conversation with John Maynard Keynes was exhausting, and noting he always came away feeling defeated. Or consider John Von Neumann, (from Steve Hsu’s very good account) who made fundamental contributions in mathematics, physics, nuclear weapons research, computer architecture, game theory and automata, and also had formidable powers of mental calculation and a photographic memory. Laureate Eugene Wigner who knew Planck, Heisenberg, Paul Dirac, Leo Szilard, Edward Teller, and Albert Einstein ranked von Neumann the highest in intellect, and the aforementioned luminaries did not question this judgement. A little uncharitably, Enrico Fermi said to Herb Anderson, with whom he ran the first ever nuclear reaction: “You know, Herb, how much faster I am in thinking than you are. That is how much faster von Neumann is compared to me”. Laureate Hans Bethe, whom I revere, went so far as to say: “I always thought Von Neumann’s brain indicated that he was from another species, an evolution beyond man”.
For general purposes, five tribes suffice. For interesting stuff, seven tribes is the better account and even then, at the higher levels, pay close attention to the order of precedence within eminent minds. For society what matters is the ease of communication between intelligence bands, the speed with which such minds can be identified and engaged in difficult tasks, and the social relations between those who differ in this important characteristic, whilst sharing so much else.Disclaimer. The above results are largely from the US and the results are mostly from the 1993 data on National Literacy with some later findings, and my main source has been Linda Gottfredson’s papers on this subject. For simplicity of exposition, I have conformed to the requirements of the current research apartheid, in which group differences between genetic groups are not reported. More recent US results include recent immigrants, and so the results may be unfair to them (not yet integrated), and by implication, to the locals as well (overall results dragged down). Results are less good for African Americans. Prof Linda Gottfredson is updating all these findings, and I will let you know when her next version is out. The account above is mostly based on white people in the USA. It would be suitable for Britain and the former British colonies which, wherever they are in the world, seem to have retained their Greenwich Mean IQ of 100. Neither the heat of the tropics nor vast spaces of the prairies or the outback, nor even far flung golf clubs and Gilbert and Sullivan societies have dented their intellect. Curious what insults the human brain can survive.