Intelligence, Personality and Genius

Tuesday, 28 February 2012

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Now that the approximate magnitude of previously estimated simple reaction times slowing over the past century or so has been confirmed

http://iqpersonalitygenius.blogspot.co.uk/2014/03/further-evidence-of-significant-slowing.html

the evidence of a significant decline in intelligence since Victorian times can no longer be dismissed or ignored.

So, the question arises what next?

1. Other researchers than myself and Michael A Woodley's group need to get involved. So long as all the results come from one group, uncertainty remains, Independent testing/ replication should be attempted.

2. While there is probably no more historical reaction time data to be had; the LPC-SO method of comparing longitudinal with cross sectional data could be applied to further samples of simple reaction times - and to other possible objective measures correlated with general intelligence and with plausible biological links to intelligence.

3. Further historical data on the effects or outcomes of intelligence may be discovered, to supplement Woodley's reanalysis of innovation rates and the incidence of creative geniuses. Any quantifiable human activity or achievement which depends strongly upon intelligence ought to show evidence of decline in-line with slowing simple reaction times.

Historical variability in heritable general intelligence: Its evolutionary origins and socio-cultural consequences. MA Woodley, AJ Figueredo - 2013 - University of Buckingham Press.

4. The effects of normal ageing on simple reaction times needs to be known with more precision - age of onset, shape of curve, sex differences and so on.

5. The quantitative relationship between simple reaction time and currently-measured IQ needs to be known - so as to make a valid conversion formula. The sRT IQ correlation coefficient is too low to make such a formula useful for individuals, but in terms of group averages it could be valuable. Such a conversion formula might turn out to be non-linear - and opens the possibility of measuring (group) intelligence on an interval or even a ratio scale.

http://iqpersonalitygenius.blogspot.co.uk/2013/02/the-ordinal-scale-of-iq-could-be.html

6. At a deeper level, an understanding the relationship between general intelligence and reaction times needs development - in particular, can 'g' be coherently defined terms of the objectively measurable speed of processing? What is the minimum possible sRT? What is the effect of slowing sRT on intelligence in terms of interactions with other cognitive constraints?

7. Assuming it is agreed that intelligence has declined very substantially over the past 150 years or so; then the mechanism of this decline needs elucidation - since the rate of decline seems to be faster (maybe even twice as fast?) than the rate predicted by the differential reproductive success of people with different IQ. My preferred explanation of intelligence being damaged by the generation-upon-generation accumulation of novel deleterious mutations (mutations which would, through most of history have led to a high probability of early death during childhood - and thereby the filtering of such mutations from the gene pool).

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Here is a list of some objections to and evidence against the assertion that average Victorian IQ would have been measured at one SD higher than moderns - that is at a modern IQ of 115 or more.

My comments follow [in square brackets]

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1. The decline of intelligence is too fast to be accounted for by known mechanisms related to differential reproductive success between the most and the least intelligent people.

[I agree, that mechanism only accounts for about half the rate of decline required to produce 1 SD slowing in simple reaction times, hence intelligence. Another mechanism, or more than one extra mechanism, is required. I favour the accumulation of deleterious (intelligence damaging) mutations generation upon generation, due to very low child mortality rates since 1800, compared with all previous times in history.]

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2. A 1 SD decline in intelligence since Victorian times would lead to a collapse of high level intellectual activity such as the number of creative geniuses and the rate of major innovations...

[I agree - it would lead to collapse...]

but this collapse has not happened - therefore there cannot have been a 1 SD decline.

[But my interpretation is that collapse has happened: the number of creative geniuses has collapsed and so has the rate of major innovations. Unless we are fooled by hype, or the self-interested self-promotion of insiders, I think this collapse is very obvious indeed across the whole of Western culture. I was writing about this collapse for many years before I came across the evidence of reducing intelligence - but I was trying to explain it in other ways such as the decline in scientific motivation, honesty, institutional factors, modern fashions, bureaucratization, Leftism etc. But the data for intellectual collapse are solid: what is in dispute are the best explanations.]

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3. Intelligence has been rising, not falling, in developed countries - as evidenced by the rising average IQ test scores - a phenomenon usually called The Flynn Effect.

[I agree that average IQ test scores rose through the twentieth century - but that this was a matter or rising test scores; meanwhile average intelligence was declining. In other words, test scores were subject to inflation - or more accurately stagflation: as when prices are rising but economic production is declining. IQ test scores were rising, but real intelligence was declining.]

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4. The evidence of slowing simple reaction times is not valid, because measurements and sampling methods in Victorian times are too different from modern measurement and sampling methods.

[Michael A Woodley and I have argued that these micro-methodological quibbles are inappropriate and invalid - and I think we have refuted them.]

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5. Simple reaction times are not a sufficiently accurate, or valid, measurement of intelligence. In fact the idea that reaction times measure intelligence is obvious nonsense, because the best fist fighters and athletes have the quickest reactions, so they would have to be the most intelligent people - but they aren't...

[Simple reaction times are nothing to do with what the general public thinks of as 'quick reactions', and nothing to do with athletics, sports, or that kind of thing. Since the mid 1800s it has been known that differences in simple reaction time - such as seeing a light flash and pressing a button, are correlated positively with differences in intelligence. The correlation is not very tight, there is a lot of scatter around the line, but there always is a correlation - and average sRT differences accurately predict measured intelligence differences between both individuals and groups such as class, sex and race. Nobody who knew the field disputed the robust correlation between sRT and IQ - and many of the main scholars (such as Jensen) have assumed that the reason for the correlation was causal - that sRT reflects speed of neural processing which is a fundamental aspect of general intelligence. It is dishonest scientific practice to overturn more than a century of good research just because the sRT results go in a direction that you find surprising.] 

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6. One SD slowing in sRT does not necessarily imply a 15 point reduction in IQ.

[I agree, because IQ is not a 'real' interval scale - which means that the difference in intelligence measured by 1 IQ point is not known and is presumably varied at different points in the scale. Reaction time is, however, an interval scale - measured in milliseconds. I have assumed that therefore sRT should take priority as the most valid scale and IQ should be calibrated against sRT. Therefore I argue that if sRT has slowed by about one SD then this should be understood to mean one SD decline in real intelligence. ]

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7. An sRT slowing of about 70 milliseconds between the 1880s and nowadays may average at about 1 IQ point per decade, but this does not necessarily imply a linear rate of decline - the rate of change may vary.

[I agree. The actual rate of decline will depend on the main causes of decline. This is not known. Indeed, if I am correct that a generation upon accumulation of deleterious and intelligence-damaging  gene mutations is an important factor - the way that this works is not known. My feeling or hunch is that this kind of effect would not be linear but that the incremental amount of damage would increase with each generation - perhaps exponentially or by some other accelerating rate. So that if there were 2 new deleterious mutations per generation, then 4 would be more than twice as harmful as 2; and 8 would be more than twice as harmful as 4 - and so on. So the rate of decline of intelligence (and slowing of sRT) over 150 years need not be linear - but I would guess it is accelerating.]

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8. There is just not enough evidence. One historical study with not very many data points is not enough to overturn the consensus from the Flynn effect studies that intelligence is rising.

[Fair point - except that the current consensus is not very secure - since confidence that rising IQ test scores really means rising 'g' (general intelligence) has never been very high. But on the other hand, the sRT historical evidence of declining intelligence is too strong to ignore. The best response is to seek further methods of confirming the decline in intelligence using different data and methods. That is what Michael A Woodley and I are doing, as best we may - but it would be great to have other people also working on the problem.]

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Saturday, 23 June 2012

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Having reflected on the title of an earlier post which described the decline in intelligence since Victorian times in terms of approximately 15 IQ points (or one standard deviation):

http://iqpersonalitygenius.blogspot.co.uk/2013/05/the-15-point-decline-in-g-since.html

And then thinking about the idea of using reaction times as a scale of general intelligence:

http://iqpersonalitygenius.blogspot.co.uk/2013/02/the-ordinal-scale-of-iq-could-be.html 

I realized that it would make more sense to most people if the decline in intelligence was expressed in terms of percentages.

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Of course this is only approximate, but if the data from Silverman's paper is used the (median) average Victorian men's reaction time was 183ms (milliseconds), while the (mean) average Modern men's reaction time was 250 ms.

http://iqpersonalitygenius.blogspot.co.uk/2012/08/taking-on-board-that-victorians-were.html

So the slowing from Victorian to Modern reaction times is 67ms

which is approx 37 percent of the Victorian reaction time of 183 ms; and 37 percent is more than one third.

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So, in a phrase and using Victorian intelligence as the baseline; it would be reasonable to say that average intelligence had declined by more than one third since Victorian times.

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And what does this 'one third' refer to?

MA Woodley talks of reaction times as a measure of core efficiency of the central nervous system - and this slowing of reaction times therefore suggests that our average thinking is biologically less efficient than the Victorians such that Victorian brains could perform an extra thirty seven percent more intelligent processing per unit time.

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One of the major limitations of IQ as a measure of general intelligence is that it is an ordinal scale, not an interval scale.

As an ordinal scale IQ is based on rank order of magnitude, so that a person with more IQ points is higher ranked than someone with fewer IQ points. But the scale's interval of the 'IQ point' has no consistent value, and strictly speaking cannot be subjected to comparative mathematical calculations.

This is because the magnitude of difference between adjacent IQ points is not known and is presumably uneven - such that the difference in test performance of 15 IQ points between IQ 130 and 115 may be different in magnitude from the difference of 15 IQ points between IQ 70 and 85 (and also differences in IQ test perfomance are themselves not usually or necessarily measurable on a meaningful interval scale).

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This is because IQ scores are constructed by doing an IQ test on a nationally representative group of people, putting the tested sample into rank order (hence ordinal scale) according to their score, then projecting the rank ordering onto a standard distribution curve with an average of 100 and a standard deviation of usually 15.

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However, if IQ could be rooted in an objective value such as reaction time, then ratios of differences between IQs could be expressed; for example, the difference between Subject A and Subject B could be said to be half or double the difference between Subject A and Subject C.

For example, Silverman gives the modern average reaction time for men as 250 milliseconds with a standard deviation of 47 - which implies that the distribution of reaction times is sufficiently near-normal (at least near to the mean) to make this summary statistic valid.

http://iqpersonalitygenius.blogspot.co.uk/2012/08/objective-and-direct-evidence-of.html

If we assume that these reaction times sample were representative of the UK population (of course they are not!), this would mean that Silverman's data could be used to generate a new type of IQ - the reaction time IQ or rtIQ using the same method as current IQ (mean of 100 and SD of 15):

                rtIQ
156ms = 130
203ms = 115
250ms = 100
297ms = 85
344ms = 70

And each rtIQ point corresponds to (47 / 15) approx 3 milliseconds difference in reaction time.

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The rtIQ would be an interval scale - based on the real magnitude of reaction times but expressed in terms of percentages, which would preserve the mathematical differences between the original reaction times measures in milliseconds.

This means that rtIQ measurements cannot be used to say something like A is 'twice as intelligent' or 'half as intelligent' as B - in other words cannot be used to describe ratios - but could be used to say, for example, that the difference in rtIQ between 115 and 130 was half of the difference between rtIQ 70 and 100 - something which cannot be done using the current ordinal IQ measurements.

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Speculative note: Ratios between numbers on an interval scale are not meaningful, so operations such as multiplication and division cannot be carried out directly.

However, the question arises whether rtIQ is not only an interval scale, but could be regarded as a ratio scale - since it is based upon a measure of time which is indeed a ratio scale such that four seconds is twice as long as two seconds.

If rtIQ is regarded as a ratio scale, then it would be true to say that a man with rtIQ would be somewhat more than twice as intelligent as another with rtIQ of 70, because a reaction time of 156ms is more than twice as quick as 344ms.

This would further imply that the range of human intelligence would be a little higher than twofold (as measured by rtIQ that includes approximately ninety-six percent of the population (plus and minus two standard deviations).

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Furthermore, the use of rtIQ sets an absolute upper limit or cut-off to human intelligence - which is the physiologically-constrained minimum reaction time - representing the maximum speed of  processing of which the nervous system is capable.

And, in fact, this upper limit would probably not be much higher than represented by a reaction time of 150ms - somewhere between 100ms and 150ms but closer to 150 than 100; since this seems to be close to the minimum time required for the physiological processes of nerve transmission (and muscle response) to be accomplished.

This would mean that the distribution of reaction times at the high intelligence end would be non-normal, and rtIQ would have a plateau. If rtIQ points continued to imply 3ms differences in rt, then the maximum rtIQ would be reached somewhere between 130 and 145.

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All this usage of reaction time as a ratio scale would make sense if, and only if, general intelligence was conceptualized in terms of something-like nervous system processing speed - akin to how 'fast' a computer is.

Clearly rtIQ is not exactly the same concept as general intelligence has been (rt is a smaller, sub-division of 'g' - although, presumably, significantly correlated with it) - and so would involve a re-definition and require replication of much of the predictive and discriminative research which has been done on g.

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From considering some of the points in this post

http://iqpersonalitygenius.blogspot.co.uk/2014/01/why-is-decline-in-average-intelligence.html

it is clear that the ageing population, the change in the age structure (as represented by a population pyramid) has been a factor in reducing average intelligence.

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Almost all nations at present have grossly distorted population structures resembling one of another of these extremes:


In terms of the median (average) age, Angola is in the late-teens, Japan is in the mid-forties.

Such extremes of median age have not been seen in human history, and such an extreme difference between nations is highly significant.

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The population structure ideal is something in between, and closer to the 'stationary' shape - therefore probably it would be roughly 'pyramidal', but with a much narrower base than Angola.

The developed world nations all approximate to the top-heavy Japanese shape among the indigenous population - very few children at the base of larger proportions of the elderly.

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As a person ages they suffer a decline in intelligence - which is objectively (but only approximately) measurable by a slowing of simple reaction times.

Reaction times get faster from young childhood up to sexual maturity as intelligence increases throughout childhood and up to about age 16 for girls and 18 for boys.

Adults are more intelligent than children - and a population grossly-over-dominated by children and early teenagers, like that of many of the developed world nations, will therefore naturally have a lower average intelligence. However, such populations would expect to get more intelligent over the short to medium term (forthcoming years to decades) as current children mature into adulthood.

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The opposite applies in the developed nations.

The reaction times/ intelligence does not change much during early adult life; but seemingly decline gets faster and faster in the thirties or forties; so the decline in intelligence from age forty to fifty is much greater than from thirty to forty, and continues to accelerate.

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(The actual amount of decline is only imprecisely known, I think, because it would require longitudinal studies lasting many decades. But as a very approximate ballpark figure, I would suggest a loss of about 10 IQ points (2/3 of a standard deviation) from age 20 to 70. Therefore the decline would go something like 30-40 - 1 IQ point lost; 40-50 - 2 IQ points lost; 50-60 - 3 IQ points lost and 60-70 - 4 IQ points lost.)

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The developed countries currently have a median average age in the mid-forties, which means that average intelligence has already declined - but as the median age gets above 45 and continues to rise, the rate of intelligence decline will increase further, and further.

At a national level, there would appear to be an apparently sudden, because more rapid, and unavoidable decline in national capability to accomplish functions requiring a population of high intelligence.

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Of course, intelligence is not the only thing that changes with age - physical ability declines, and personality also changes - but the objective nature of reaction times makes the picture simpler and more objectively measurable, in principle.

(Objectively measurable, that is, at the population level where the imprecision of simple reaction times for estimating individual intelligence, is overcome by averaging of larger numbers.)


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The point is that a population with a top-heavy population pyramid, a population with a median age in the forties and increasing, is a population with:

1. Reduced average intelligence compared with the optimal population structure - and the transition of population structure to the top-heavy form would be accompanied by an increasingly rapid reduction in average intelligence from this cause;

2. And a population with high median age/ top-heavy structure is a population where further and more rapid decline in average intelligence is to be expected over the short to medium term (the coming years, and next few decades; due to the small proportion of the population contained in those age- cohorts that will be moving into young adulthood (with peak intelligence) in the near future.


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Note: Of course, the Leftist media propound sustained mass immigration as a solution to this problem; but of course it is not a solution to this problem and very obviously leads to multiple other and intractable problems.

Suffice to say, any potential immigrant groups that could theoretically improve the cognitive deficit will not improve (and probably worsen) the reproductive deficit - and vice versa.

In the long term, the current top-heavy population structure of the developed nations will self-correct, because it is unsustainable in multiple ways; and thus the ageing-contribution to intelligence decline will cease.

However, the intelligence level of the population which stabilizes will, of course, be significantly lower than it was 150-200 years ago - due to the substantial intelligence decline over that period.

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This is a re-analysis of the data from Deary IJ, Der G. Reaction time, age and cognitive ability: longitudinal findings from age 16-63 years in representative population sampless. Aging, Neuropsychology and Cognition. 2005; 12: 187-215.

The principle is that data on the longitudinal slowing of simple Reaction Times (sRTs) measured in longitudinal follow-up studies of segments through the human lifespan, may be interpolated to predict the expected slowing in sRT between 16 and 63; the prediction is compared with the actual measured sRT in cross-sectional studies at ages 16 and 63. 

In other words, the longitudinal data is used to construct an 'ageing curve' which describes the expected slowing of reaction times through the lifetime of an average person. But it was found that the measured reaction times of elderly people were considerably faster than would be expected from the effect of ageing of the youngest cohort - consistent with a generation by generation slowing in sRT. 

The difference between the predicted and observed sRT of elderly people is a measure of the slowing of sRT (ie. 'secular' change, or presumed dysgenic change) over the span of 47 years - and this can be extrapolated to estimate the slowing of sRT expected over longer periods (assuming that the rate of sRT slowing is constant).

This Longitudinal Prediction Cross-Sectional Observation (LPCSO) method predicts a slowing of sRT of about 80 ms in a century, which is very similar to the measured difference of 70ms slowing between Victorian and modern sRT. 

This confirms the very substantial slowing of sRT since the 1800s, from about 180 ms to about 250 ms (a slowing of about one or more standard deviations of modern sRT) which must surely orrespond to a significant decline in general intelligence.

The LPCSO method could be used on other sRT data sets to check this result - and also applied to other possible measures of dysgenic or secular trends.

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Predicted sRT at each age
Age	msec
16	295
24	306
36	327
44	344
56	383
63	413

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Okay - so simple reaction time data indicates that average general intelligence has declined by about one standard deviation (15 IQ points) since the late 1800s.

http://iqpersonalitygenius.blogspot.co.uk/2012/08/taking-on-board-that-victorians-were.html

http://iqpersonalitygenius.blogspot.co.uk/2012/11/the-over-promoted-society-bishops-and.html

http://iqpersonalitygenius.blogspot.co.uk/2013/02/what-are-genetic-causes-of-dysgenic.html

http://iqpersonalitygenius.blogspot.co.uk/2013/05/the-decline-in-general-intelligence.html 

What next?

Should we believe it?

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Well, here are a few considerations:

1. Simple reaction times are the most objective evidence we have concerning trends in general intelligence.

Therefore we should:

a. believe them, or

b. come-up with something better, or

c. show how these studies of reaction times are incompetent, or

d. assume that the studies of reaction times are dishonest, or

e. assume that this data is wrong on the basis that most data is wrong (and because we are under no obligation to believe any particular bit of data - quite the contrary, there must be good reasons for believing any specific proposition)

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2. Any other data which can be brought to bear on the matter of declining intelligence is (I think) relatively 'soft', subjective and imprecise compared with reaction times - (things like rates of major innovation, rates of geniuses etc) so - although I see much of what seems to be consistent with a significant and relatively rapid decline in general intelligence - it is unlikely to convince someone who does not want to believe in the first place.

On the other hand, even if it does not support, does any of this long terms evidence of general intelligence contradict the thesis that it has declined?

I mean, is there any decent evidence that general intelligence has actually risen? (aside from the Flynn effect of increasing pen and paper IQ test scores - which is not relevant here since it is what is being explained, and therefore inadmissible as evidence).

Has, for instance, per capita performance improved since the late 1800s in any 'g' related and quantifiable human endeavour? I know this is tricky to answer, since there are shifts in the specialized activities of intellectuals (e.g. away from study of The Classics and towards some of the sciences, or medicine) - but is there is reasonably compelling evidence of this sort of improvement?

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3. If is is decided that we should, after all, accept the best evidence as showing a significant decline in average intelligence since the late 1800s, then there is quite a lot of further work to be done on the mechanism - because, on the whole, present understanding of 'dysgenic' mechanisms in relation to intelligence is not adequate to explain the rapidity of this decline.

(I mean, that calculations based on differential reproduction and heredity of intelligence predict a much slower rate of decline than could lead to one SD reduction in 'g' in the space of just four or five generations.)

The accumulation of deleterious mutations with the relaxation of selection due to high rates of child mortality is my first best guess at the likely 'extra' mechanism (and Michael Woodley agrees)

http://iqpersonalitygenius.blogspot.co.uk/2013/02/what-are-genetic-causes-of-dysgenic.html


but really this is just a best guess, and the detailed mechanisms of how this might work are unclear.

However, it could make interesting science in trying to find-out!

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Greg Cochran has been the most significant (intellectually substantial) critic and opponent of the idea (deriving from myself and Michael A Woodley) that historical reaction time data have shown a significant (approx. one standard deviation or 15 modern IQ point) decline in intelligence since Victorian times. 

[http://charltonteaching.blogspot.co.uk/2012/06/taking-on-board-that-victorians-were.html]

In his latest blog posting, Greg takes another side swipe at the idea.

http://westhunt.wordpress.com/2014/03/05/outliers/

Here is my comment in response.

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1. Do you believe that Victorian simple reaction time (sRT) data are not comparable with modern data? If so, would you be convinced by evidence of rapidly slowing reaction times over recent decades, measured in one laboratory and using only modern RT machines? Because this kind of evidence is in the pipeline.

2. Do you believe that - despite about 140 years consensus that sRT and IQ are significantly correlated, and the general belief that this correlation is because general intelligence is dependent upon processing speed of which sRT is an indirect measure - there is NOT a causal relationship between simple reaction times and intelligence? That, therefore, average sRTs could be getting much, much slower but that this would not necessarily make any difference to average intelligence?

3. Do you believe that the measured decline in average simple reaction time from a Victorian sRT average speed of about 180 milliseconds (in several independent studies) to a modern average speed of 250 milliseconds (or slower), a slowing of 70 milliseconds plus - is not enough to be of interest: that it is too small to not reflect any significant or meaningful reduction in intelligence.

4. Do you believe that because the measured slowing of sRT over the past 150 years seems unexpected, and is larger than you would have supposed possible, strikes you as indeed ludicrous - that therefore we should simply ignore it?

5. Do you believe that - because the data on long term sRTs seems anomalous with your world view, that we should therefore assume that somehow there is something wrong somewhere with the Victorian to Modern comparison; and therefore we should just carry-on just as if we knew nothing about longitudinal changes in sRTs?

6. Do you believe that there has been a significant reduction in average general intelligence over the past 150 years, but that it is much less than one standard deviation - probably more like HALF a standard deviation? And the large size of the sRT slowing is just a Red Herring?

7. Do you believe that average intelligence has NOT changed over the past 150 years - that moderns have the same intelligence as Victorians? And the slowing of average sRT is irrelevant?

8. Do you believe that average intelligence has increased over the past 150 years despite slowing of sRTs, because you believe the pen-and-paper IQ tests are more valid, reliable and/or objective than reaction time data?

9. Or something else, or what?

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The phrase and practice of "extraordinary claims require extraordinary evidence" is one of those superficially-plausible statements which are untrue, and indeed damagingly false.

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Of course, this does not mean we should believe anything anybody might say no matter how absurd - but in practice the whole thing hinges on the meaning of 'extraordinary'.

In practice:

1. The definition of an extraordinary claim is 'something I don't already believe'...

While

2. The definition of extraordinary evidence is that no amount of evidence will ever be enough to convince me of that.

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People find all sorts of things extraordinary which are not.

Modern atheist intellectuals, for example, find the idea of God or gods to be extraordinary, and all kinds of other things such as souls, angels and demons, the Virgin Birth and the resurrection of Christ - plus all sorts of things like telepathy and prophetic dreams - despite that these are not extraordinary to the vast majority of people alive, and to almost nobody in the sweep of human history.

Claims of the reality of things may or may not be factually correct - in general, or specifically - but these are not extraordinary claims - and the 'evidence' for them is of exactly the same nature as for anything else.

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In science, a major area which asks for extraordinary evidence is claims of group differences in hereditary personality and intelligence. Around about 1965, it was rather suddenly decided that the claim of heritable group differences was extraordinary, and extraordinary evidence was demanded - and fifty years of research later exactly the same demand is still being made.

Each piece of evidence in support of the supposedly-extraordinary claim of heritable group differences is put under a microscope to check for flaws - and of course flaws can be found - especially when people don't look use the same microscope to study the beliefs that they believe.

So, those who reject heritable group differences believe what they believe, and which (because they believe it) they do not regard as extraordinary - and accept any further evidence in support of this belief with just a cursory glance; but anything they don't want to believe is checked, inch by inch, under a microscope and - guess what? - is found to have flaws! Therefore they feel justified in rejecting it.

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This pretends to be 'rigorous' ('Look at me - I'm a real scientist! I'm using a microscope!') but it is of course, that is phony science, politicized science.

Indeed, the practice of accepting supporting evidence at a glance while putting opposing evidence under a microscope is not just bad science - it is not science at all.

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Yet even outside of politics this technique of differential rigour is an easy trap to fall-into - indeed there are very few who are exempt.

This is something to be guarded against.

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When I was editor of Medical Hypotheses it was the last major non-peer reviewed journal in science - and its special value was that it had the potential to overcome the intrinsic bias of 'peers' to defend the existing paradigm by demanding 'extraordinary' evidence for any new work which disagreed with the prevailing paradigm.

But what if the evidence for the prevailing paradigm is weak?

In modern professional science there are many dominant but evidentially (and logically) weak research paradigms - but these are defended as tenaciously - or even more tenaciously, than coherent and strongly supported paradigms.

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For example, in psychiatry there is a decades-established prevailing explanation of 'depression' in terms of neurotransmitter abnormalities and of treatment by 'antidepressants' which correct these presumed abnormalities.

This paradigm does not make any sense and there is no evidence to support it - yet 'everyone' believes it - and any alternative perspectives are (therefore?) treated as requiring 'extraordinary' levels of evidence, such as clear and unambiguous support from multiple multi-million-dollar, mega-randomized controlled trials. Hence the prevailing nonsense is impregnable.

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Declaration of interest: all this stuff is happening, now, to me and Michael A Woodley et al with respect to the use of longitudinal reaction time data to estimate long term trends in general intelligence.

http://iqpersonalitygenius.blogspot.co.uk/2013/05/the-e-mail-when-i-had-idea-of-using.html

http://iqpersonalitygenius.blogspot.co.uk/2013/05/the-decline-in-general-intelligence.html 

The problems are that the result contradicts current notions of:

1. Direction 

2. Size

3. Rapidity

of change in intelligence. Therefore the result challenges the current paradigm in several respects.

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To put it another way, Woodley and myself are regarded as making an extraordinary claim - and this is used to justify putting this particular study under an extra-powerful methodological microscope (and if that doesn't suffice - an electron microscope) to search for, and inevitably find, microscopic cracks (gaps) and flaws (distortions) in the evidence.

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But consider the counter-factuals.

Suppose that the data had shown a reduction in reaction time since the Victorian era (implying increasing intelligence) - which would be consistent with the Flynn effect - what would people have done?

In other words, what if the study - and I mean exactly the same study in terms of exactly the same evidence and methodology - had found exactly what people expected it to find?

Well, of course this would not have been an 'extraordinary' claim, so people would have accepted the study as a matter of course and without further discussion.

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But suppose (again counter-factually) that the study (exactly the same data set and methodology) had instead found a small increase in reaction time? Implying a small reduction in average intelligence?

Well, that too would have been accepted without much discussion - since it would not signify much either way.

Nobody would have put the study under an electron microscope. 

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But in real life the data showed a big increase in reaction times implying a big reduction of intelligence since Victorian times.

This is indeed a paradigm-shifting claim; and it is 'therefore' regarded as an extraordinary claim - and therefore this is used to justify (as described above) extraordinary examination of the claim - on the basis of the slogan in the title.

But is this an extraordinary claim?

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If it really was extraordinary to claim that intelligence had declined by about one standard deviation since Victorian times, it would be easy to present many evidences and examples which very obviously refuted that claim.

Yet none have been presented.

Obviously, the best way to reject a claim is to refute it with clear and unambiguous contrary evidence - and if you are reduced to quibbling over methodology, then the claim is revealed as being not extraordinary - and therefore not requiring extraordinary levels of micro-critique.

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So, although people feel that the claim of a rapid and significant decline in intelligence is so extraordinary as to invite extreme skepticism; in practice - or so it seems - it is not easy to refute this claim without stepping outside of real science and becoming the kind of phony, fake, pseudo-scientist who polices the field of heritable IQ group differences.

And this is what we find.

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Under pretence of rigour, there is not just bad science, but non-science - anti-science.

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So, if micro-analysis of potentially paradigm changing claims is revealed as anti-science, then what should be done?

Well, paradigm-changing claims should be evaluated in the same way and to the same standards of research competence and honesty as paradigm-supporting claims.

When a piece of research reaches the normal standards of competence and honesty, yet has extraordinary implications, then it is distorting and inappropriate and in fact anti-science to dwell upon the micro-details of this research.

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The correct thing to do is to recognize that in real science multiple evidences converge upon the truth.

That is exactly why science is important - because true scientific claims have multiple consequences - or, to put it another way, the implications of important true theories ramify through reality, and therefore their consequences can be observed in many places.

So when the claim of reduced intelligence is based upon longitudinal change in reaction times, then the matter is not to be settled 'methodologically' by ever more, ever more voluminous and complex and precise measurements of reaction times - but instead by seeking convergent evidence from different fields - by tracing out the implications of the claim through reality until these implications go into places where they can be observed and checked.

Therefore, what is needed is to discover what would-be the implications of a significant and rapid decline in average intelligence, and then make observations to see whether these implications really have happened.

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If the claim of an approximately one standard deviation decline in intelligence since Victorian times really is false; then, because this is a very significant claim, it should be easy to discover some strong evidence which contradicts the claim.

But such a claim need not, and certainly should not be required to, meet 'extraordinary' standards of evidence!

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In conclusion:

If a claim is both 'extraordinary' and also wrong, it must be trivially easy to refute.

But if a claim which seems 'extraordinary' cannot in practice easily be refuted; then it is not really an extraordinary claim, and should not be treated as such. 

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IJ Deary, G Der. Reaction Time, Age, and Cognitive Ability: Longitudinal Findings from Age 16 to 63 Years in Representative Population Samples. Aging, Neuropsychology, and Cognition  2005; 12: 187-215.

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Deary and Der's paper referenced above seems to be the best available estimate of the effects of ageing on simple reaction times (sRTs).

Simple reaction time correlates with general intelligence (g) and there is, I believe, a lot of reason to believe that group-averaged sRTs are the best, most valid measure of long-term changes in intelligence.

At the individual level, the modest correlation of sRT with IQ makes the sRT a relatively poor predictor of cognitive; but this is dealt with be averages the sRT measure in a large group, and of course the sRT is a real, physiological measure on a ratio scale - while IQ is only a measure of relative performance in tests, and is merely an ordinal scale with has no fixed interval measure or zero.

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It is well known that general intelligence declines from late teens/ early twenties and into old age - for example as measured by fluid intelligence. In other words, raw scores of fluid intelligence in IQ tests will decline.

But the real magnitude of this decline cannot be obtained from IQ testing - and only a ratio scale, physiological functional measure such as sRT can measure the real magnitude of decline.

Deary and Der 2005 make possible this measure. They measure Men and Women in three cohorts: aged 16 retested at 24; age 36 retested at 44; aged 56 retested at 63. So, there are six data points for men, and another six for women.

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Simple visual Reaction Times in milliseconds (rounded to nearest integer)
- Mean (Standard Deviation)

MEN

16- 293 (72)
24- 294 (78)

36- 304 (75)
44- 316 (90)

56- 348 (109)
63- 373 (124)

Total decline 16-63 - 373 minus 293 = 80 milliseconds.

Using age 16 average as a baseline value with its standard deviation of 72 - this 80 ms decline represents an intelligence decline of slightly more than one standard deviation - i.e. slightly more than 15 IQ points.

So, an average man of average IQ would decline from 50th centile age 16 to somewhat below the 16th centile aged 63.

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WOMEN

16- 295 (57)
24- 306 (73)

36- 314 (79)
44- 333 (95)

56- 346 (101)
63- 375 (126)

Total decline 16-63 - 375 minus 295 = 80 milliseconds.

So, using age 16 as a baseline value with its standard deviation of 57 - this 80ms decline represents an intelligence decline of significantly more than one standard deviation - i.e. significantly more than 15 IQ points.

So, an average woman of average IQ would decline from 50th centile to significantly below the 16th centile aged 63.

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A decline of more than one standard deviation - or 15 IQ points, represents the minimum average decline in general intelligence from 16 to 63 - in women the real value is likely to be even larger, because the three cohorts of 16-24, 36-44 and 56-63 very probably had different starting levels for intelligence - with the oldest age group having had a starting (age 16) sRT of about 36ms faster than the measured value for the 16-24 group.  See:

https://docs.google.com/file/d/0B3-9JKn2PJz3cTNFWHhUbHFXdDg/edit

This may be taken imply that among women the true decline of sRT from 16-63 is more like 113 ms instead of 80 ms - and 113 ms decline would be two standard deviations.

However, 2SDs is likely to be an overestimate, because the distribution of sRT is not really a normal distribution, but positively skewed such that there is a longer tail of higher values - so the standard deviation breaks down as a valid description after about one standard deviation.

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Nonetheless the data presented in Dear and Der 2005 seems to be measuring a very significant degree of decline in real, underlying, physiological general intelligence/ fluid intelligence between ages 16 and 63; suggesting a significant decline in those cognitive aptitudes underpinned by g.

In practice, this decline in general intelligence may well be obscured by increased specific or 'crystallised' intelligence, due to accumulated specific knowledge, skills and expertise. But the decline in g would be apparent in reduced cognitive flexibility, e.g. slowing of the learning of new knowledge and skills, reduced capacity at solving novel problems and so on.

This data set also suggests that the effect of declining intelligence with age may also be obscured, in this group of women, by declining average intelligence over time, with older generations having a had a higher starting point of for intelligence.

But however the data is adjusted or corrected, the basic finding seems to be that average intelligence declines by more than one standard deviation from age 16 to 63.

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Ref: see also

http://iqpersonalitygenius.blogspot.co.uk/2014/03/further-evidence-of-significant-slowing.html