Reaction times are strongly correlated with IQ which, in turn, has strong inverse correlations with many of the characteristics for people who are, and have been, reproducing the most. The paper proposes this, 'dysgenic fertility', as a possible explanation. As an aside this is not an implicit reference to e.g. Africa. This problem exists on an international and intranational level. E.g. in the US people who have household income of less than $10,000 have a fertility rate 150% that of those with a household income greater than $200,000 with a surprisingly smooth fertility:income gradient between the two. [1]
Crucially, the heritability of IQ seems to be only increasing the more we learn about it. Older studies showed it to 'only' be around 60% with more modern research indicating it is upwards of 80%. [2] One peculiar, and confounding effect, here is how IQ behaves on youth. In young age environmental conditions can play a more substantial role in IQ, yet as youth approach adolescence and beyond their IQ tends to approach their 'genetic expectation.'
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And all the above assumes something many do not seem aware of (based on a different thread). IQs in the developed world seem to have started to substantially decline with no viable convenient explanation. Environmental or educational conditions achieving diminishing returns are what we would like to believe, yet of course if that was the case we'd expect to see an asymptotic decline of growth approaching 0. Instead we are seeing an actual decline in IQ. [3] One conflicting bit here is that most evidence indicates this decline started happening sometime in the mid 90s. Prior to that IQs had been increasingly, though more slowly over time - but that decline of growth is to be expected.
IQs in the developed world seem to have started to substantially decline with no viable convenient explanation.
Maybe what's happening is that IQ has been declining for a longer time, but the gains in health and nutrition were offsetting the effect. An interesting variable to compare to is life expectancy, which is a proxy for health. Its growth in western countries has been slowing and in the US it has even started declining. Studies have shown a link between IQ and life expectancy. Those studies generally looked towards a reason why higher IQ would lead to higher life expectancy, but perhaps the causation is reverse.
We do not even have good enough data to support IQ results in a single generation related to this... (there are problems when checking across cultures)
Additionally, the tests were modified over time.
Is the reaction test the same? Was it checked for reproducibility? Has an alternative hypothesis of slower muscle speed been excluded?
So, drawing any conclusion from these numbers is very, very risky, even riskier over time - unless you somehow invent time travel and give Victorian era people the exact same test we give people now.
Remember, IQ tests are graded across average in a generation...
One standard measurement of IQ is the Stanford-Binet exam. It's been around since 1916 with extensive concern given to consistency in the 5 updates it has received over the century. And that consistency is determined through thousands of trials with demographically representative samples to avoid predictable issues like a self selection bias in testing.
But like you mention the tricky part is that IQ is measured across an average in a generation. The mean is normalized to 100 with a standard deviation of about 15 points. An IQ of 115 does not mean you 'scored' 115 in a vacuum, it means you performed better than 84% of people. The idea that IQ would substantially increase or decrease for an entire population over very short periods of time (thus changing the meaning, in a vacuum, of e.g. 115 IQ over short periods of time time) was surprising, and that's precisely what the Flynn Effect [1] is. However that change is precisely measurable and enables researchers to produce comparable values between generations.
Re: correlation of income to fertility. The causation could perhaps go the other way when looked at as potentially genetic preference for smaller families. Smaller families mean children receive a larger percentage of their parents' time and money which will give them an advantage over children whose parents divide their resources among more children. Of course effective birth control is still so new that it throws a wrench in this argument.
Does anyone have access to the paper referenced in the quote about the measurement inaccuracy "deemed unlikely"? I'm calling B.S. unless they can quantify that bold claim
Better to suppose "some" and not generalize for the universe of all possible people.
Furthermore, nowhere is the process of measurement, or quality measured, noted. Is it simple reflex tests (tapping the knee with a small rubber mallet) or something else?
It doesn't sound like they actually compared apples to apples by performing the same test as a modern replication of results though.
A similar apparatus is not named or sited, when noting the modern equivalent. Does that matter? Couldn't there be side-effects for measure reation time to different stimuli?
Also, did modern 1941 measurements operate with the benefit of newer advancements, such as high-speed cinematography to produce objective slow-motion footage?
>The Victorian era was marked by an explosion of innovation and genius, per capita rates of which appear to have declined subsequently. The presence of dysgenic fertility for IQ amongst Western nations, starting in the 19th century, suggests that these trends might be related to declining IQ. This is because high-IQ people are more productive and more creative. We tested the hypothesis that the Victorians were cleverer than modern populations, using high-quality instruments, namely measures of simple visual reaction time in a meta-analytic study. Simple reaction time measures correlate substantially with measures of general intelligence (g) and are considered elementary measures of cognition. In this study we used the data on the secular slowing of simple reaction time described in a meta-analysis of 14 age-matched studies from Western countries conducted between 1889 and 2004 to estimate the decline in g that may have resulted from the presence of dysgenic fertility. Using psychometric meta-analysis we computed the true correlation between simple reaction time and g, yielding a decline of − 1.16 IQ points per decade or − 13.35 IQ points since Victorian times. These findings strongly indicate that with respect to g the Victorians were substantially cleverer than modern Western populations.
It's not terribly convincing just by itself. He's done newer work showing that other proxies for IQ like vocabulary have also decreased over time: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4404736/ And math SAT scores have dropped over time: https://brainsize.wordpress.com/tag/michael-a-woodley/ But we are only just starting to be able to test for genes that correlate with intelligence to see if they have decreased over time.
One complaint IIRC was that the Victorian sample might have been more skewed towards the elite than the current ones -- people attending science lectures, or something.
I haven't read the paper linked, Woodley-teNijenhuis-Murphy, but do they address this?
Did he even bother checking error bars due to multiple test correction when verifying the correlations in pooled data?
We could ask Cochrane what they find. They tend to use many more studies than 14 as input with clear inclusion and exclusion criteria.
I suspect the author misuses statistics and fails to check internal and external validity of his measures.
How did he even get the real IQ points when the test had been changed and regraded about every 20 years? How does he convert the numbers to g? Is it general or slanted? Is his measure verified to be consistent even in a single generation across cultures? Etc.
Unfortunately, the other paper is behind the paywall.
> It is believed that cytokine storms were responsible for the disproportionate number of healthy young adult deaths during the 1918 influenza pandemic, which killed 50 to 100 million people.[12] In this case, a healthy immune system may have been a liability rather than an asset. Preliminary research results from Hong Kong also indicated this as the probable reason for many deaths during the SARS epidemic in 2003.[13] Human deaths from the bird flu H5N1 usually involve cytokine storms as well.[14] Cytokine storm has also been implicated in hantavirus pulmonary syndrome.
It's increasingly becoming clear that at least some part of the IQ is inheritable and that IQ has been falling for last 2 decades or longer as if the high IQ populace has lost their reproductive edge, probably artificially? Contraceptives are increasingly being used and women have the equal right so no one can force a woman to bear his child. Countries being analyzed have some form of welfare, so no one dies starving. Vaccines and expert help are easier to come by and the internet also helps here a lot. All this means, high IQ probably can help you earn millions but low IQ does not mean you die. Also, today high IQ populace is easier to discover, reward and keep busy with exciting work, so maybe they are no longer finding time to reproduce. And the ones who do not possess high IQ have plenty of time to have kids and take care of them. We've drastically changed the environment in which we live, so obviously, there will be some consequences. Then also our environment has evolved enough that we no longer need high IQ to survive.
Not this bullshit research again... Woodley is a dishonest crank. Anyone conducting research in bad faith should be exiled to deep space, it’s incredibly damaging. Andrew Wakefield is another one (https://en.m.wikipedia.org/wiki/Andrew_Wakefield).
>In this paper, we reconsider a tendency of historical slowing of simple reactions to visual stimuli declared by Woodley et al. (in press). We begin by reconstructing a pendulum similar to that used by Galton and question whether such an instrument could indeed be appropriate for purposes of RT measurement. Next, we screened the other studies used in Woodley's meta-analysis and note the important properties of these studies that make the RTs that they report incomparable to each other. We claim that there is no evidence of the trend of historical increase in RT after these differences between studies are taken into account. Overall, we conclude that any cross-study comparison of RTs is uninformative and cannot provide any evidence for speculating on the topic of historical change in intelligence.
> Based on Digit Span Forward (DSF) and Digit Span Backward (DSB) adult test scores across 85 years of data (respective Ns of 7,077 and 6,841), the mean adult verbal STMC was estimated at 6.56 (± 2.39), and the mean adult verbal WMC was estimated at 4.88 (± 2.58). No increasing trend in the STMC or WMC test scores was observed from 1923 to 2008, suggesting that these two cognitive processes are unaffected by the Flynn effect.
I would be interested in trying modern people with the original measuring equipment. I'll bet that when the timer starts there is some tactile click that allows for a quicker reaction than visual or auditory. I'll bet what is really being measured here is the difference in reaction times between different sensory paths.
33 comments
[ 3.8 ms ] story [ 81.8 ms ] threadI wonder if there's a toxicological or immunological explanation, or whether it's simply due to differing recreational and activity choices.
Crucially, the heritability of IQ seems to be only increasing the more we learn about it. Older studies showed it to 'only' be around 60% with more modern research indicating it is upwards of 80%. [2] One peculiar, and confounding effect, here is how IQ behaves on youth. In young age environmental conditions can play a more substantial role in IQ, yet as youth approach adolescence and beyond their IQ tends to approach their 'genetic expectation.'
---
And all the above assumes something many do not seem aware of (based on a different thread). IQs in the developed world seem to have started to substantially decline with no viable convenient explanation. Environmental or educational conditions achieving diminishing returns are what we would like to believe, yet of course if that was the case we'd expect to see an asymptotic decline of growth approaching 0. Instead we are seeing an actual decline in IQ. [3] One conflicting bit here is that most evidence indicates this decline started happening sometime in the mid 90s. Prior to that IQs had been increasingly, though more slowly over time - but that decline of growth is to be expected.
[1a] - https://www.statista.com/statistics/241530/birth-rate-by-fam...
[1b] - https://www.census.gov/topics/health/fertility.html (the statista graph presents this data in a cleaner format - adding this as just a more reliable source than random internet site)
[2] - https://en.wikipedia.org/wiki/Heritability_of_IQ
[3] - https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_p...
Maybe what's happening is that IQ has been declining for a longer time, but the gains in health and nutrition were offsetting the effect. An interesting variable to compare to is life expectancy, which is a proxy for health. Its growth in western countries has been slowing and in the US it has even started declining. Studies have shown a link between IQ and life expectancy. Those studies generally looked towards a reason why higher IQ would lead to higher life expectancy, but perhaps the causation is reverse.
Is the reaction test the same? Was it checked for reproducibility? Has an alternative hypothesis of slower muscle speed been excluded?
So, drawing any conclusion from these numbers is very, very risky, even riskier over time - unless you somehow invent time travel and give Victorian era people the exact same test we give people now.
Remember, IQ tests are graded across average in a generation...
But like you mention the tricky part is that IQ is measured across an average in a generation. The mean is normalized to 100 with a standard deviation of about 15 points. An IQ of 115 does not mean you 'scored' 115 in a vacuum, it means you performed better than 84% of people. The idea that IQ would substantially increase or decrease for an entire population over very short periods of time (thus changing the meaning, in a vacuum, of e.g. 115 IQ over short periods of time time) was surprising, and that's precisely what the Flynn Effect [1] is. However that change is precisely measurable and enables researchers to produce comparable values between generations.
[1] - https://en.wikipedia.org/wiki/Flynn_effect
https://thinkprogress.org/exclusive-elevated-co2-levels-dire...
https://mindhacks.com/2018/04/03/did-the-victorians-have-fas...
Kind of an artificial make-believe people set.
Better to suppose "some" and not generalize for the universe of all possible people.
Furthermore, nowhere is the process of measurement, or quality measured, noted. Is it simple reflex tests (tapping the knee with a small rubber mallet) or something else?
http://galton.org/bib/JournalItem.aspx_action=view_id=180
It's a pendulum which is released (either silently or with a click), and a button for the subject which records the angle at which it was pressed.
A similar apparatus is not named or sited, when noting the modern equivalent. Does that matter? Couldn't there be side-effects for measure reation time to different stimuli?
Also, did modern 1941 measurements operate with the benefit of newer advancements, such as high-speed cinematography to produce objective slow-motion footage?
>The Victorian era was marked by an explosion of innovation and genius, per capita rates of which appear to have declined subsequently. The presence of dysgenic fertility for IQ amongst Western nations, starting in the 19th century, suggests that these trends might be related to declining IQ. This is because high-IQ people are more productive and more creative. We tested the hypothesis that the Victorians were cleverer than modern populations, using high-quality instruments, namely measures of simple visual reaction time in a meta-analytic study. Simple reaction time measures correlate substantially with measures of general intelligence (g) and are considered elementary measures of cognition. In this study we used the data on the secular slowing of simple reaction time described in a meta-analysis of 14 age-matched studies from Western countries conducted between 1889 and 2004 to estimate the decline in g that may have resulted from the presence of dysgenic fertility. Using psychometric meta-analysis we computed the true correlation between simple reaction time and g, yielding a decline of − 1.16 IQ points per decade or − 13.35 IQ points since Victorian times. These findings strongly indicate that with respect to g the Victorians were substantially cleverer than modern Western populations.
It's not terribly convincing just by itself. He's done newer work showing that other proxies for IQ like vocabulary have also decreased over time: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4404736/ And math SAT scores have dropped over time: https://brainsize.wordpress.com/tag/michael-a-woodley/ But we are only just starting to be able to test for genes that correlate with intelligence to see if they have decreased over time.
I haven't read the paper linked, Woodley-teNijenhuis-Murphy, but do they address this?
The effects might be interesting, but it seems like an entirely unsupported logical leap to attribute any effect to this cause.
We could ask Cochrane what they find. They tend to use many more studies than 14 as input with clear inclusion and exclusion criteria.
I suspect the author misuses statistics and fails to check internal and external validity of his measures.
How did he even get the real IQ points when the test had been changed and regraded about every 20 years? How does he convert the numbers to g? Is it general or slanted? Is his measure verified to be consistent even in a single generation across cultures? Etc.
Unfortunately, the other paper is behind the paywall.
> It is believed that cytokine storms were responsible for the disproportionate number of healthy young adult deaths during the 1918 influenza pandemic, which killed 50 to 100 million people.[12] In this case, a healthy immune system may have been a liability rather than an asset. Preliminary research results from Hong Kong also indicated this as the probable reason for many deaths during the SARS epidemic in 2003.[13] Human deaths from the bird flu H5N1 usually involve cytokine storms as well.[14] Cytokine storm has also been implicated in hantavirus pulmonary syndrome.
"Is there any evidence of historical slowing of reaction time? No, unless we compare apples and oranges" (https://www.sciencedirect.com/science/article/pii/S016028961...)
>In this paper, we reconsider a tendency of historical slowing of simple reactions to visual stimuli declared by Woodley et al. (in press). We begin by reconstructing a pendulum similar to that used by Galton and question whether such an instrument could indeed be appropriate for purposes of RT measurement. Next, we screened the other studies used in Woodley's meta-analysis and note the important properties of these studies that make the RTs that they report incomparable to each other. We claim that there is no evidence of the trend of historical increase in RT after these differences between studies are taken into account. Overall, we conclude that any cross-study comparison of RTs is uninformative and cannot provide any evidence for speculating on the topic of historical change in intelligence.
another interesting paper on this topic is:
"The magical numbers 7 and 4 are resistant to the Flynn effect: No evidence for increases in forward or backward recall across 85 years of data" (https://www.sciencedirect.com/science/article/pii/S016028961...)
> Based on Digit Span Forward (DSF) and Digit Span Backward (DSB) adult test scores across 85 years of data (respective Ns of 7,077 and 6,841), the mean adult verbal STMC was estimated at 6.56 (± 2.39), and the mean adult verbal WMC was estimated at 4.88 (± 2.58). No increasing trend in the STMC or WMC test scores was observed from 1923 to 2008, suggesting that these two cognitive processes are unaffected by the Flynn effect.