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With the recent confirmation from reaction time measurements that average intelligence has objectively and significantly declined from Victorian times until now,
http://charltonteaching.blogspot.co.uk/2012/02/convincing-objective-and-direct.html
the next step is to start taking this fact into account, and unpacking its implications...
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First, how much has reaction time/ intelligence declined?
Prof Silverman reviews data from Francis Galton between 1884 and 1893, extracted from a study of visual reaction times in 2,522 men and 302 women. The average reaction times were 183 milliseconds (ms) for men and 0.187 ms in women.
Silverman notes that in reviews of reaction time studies in 1911 (but not including Galton's work), it is clear that Galton's results were typical of the era - the range being from 151-200 milliseconds - median of 192 milliseconds.
By contrast, Silverman reviews twelve modern (post 1941) studies of visual reaction time (using a comparable methodology to Galton) - and the modern reaction times are very significantly longer - the total number of subjects was 3,836 - the mean reaction time was 250 milliseconds for men (SD 47) and for women was 277 ms (SD 31).
Looked at separately, in only one study, only for men, were Galton's average values contained within the 95 % confidence interval - in other words, in 11 of 12 studies and 19 of 20 comparisons - as well as the overall meta-analysis - the difference in reaction times reaches conventional levels of statistical significance.
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We do not have a standard deviation (measure of scatter) for the Victorian data - so we need to compare (looking at men) a (mean) average modern reaction time of 250 milliseconds (SD 47) with a (median) average Victorian RT of 183.
This implies that average (and being conservative in my interpretation) Victorian reaction times were more than one standard deviation faster than modern RTs; or, that the average Victorian would be placed comfortably in the top 15 percent of the modern population - probably higher.
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If we assume that reaction time is a valid measure of general intelligence, in other words that RT has a linear correlation with g - then this would mean that the average Victorian Englishman had a modern IQ of greater than 115.
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Does this degree of difference in IQ make for a significant difference in performance?
Well, yes - it certainly does.
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The difference between the modern IQ standardized at 100 and the Victorian IQ of 115 plus would be somewhat greater than:
1. The difference between an unselective 'comprehensive' school which had an average population, and a highly selective 'grammar school'
2. A mainstream US state university and an Ivy League college
3. The cognitive ability of high school teachers compared with doctors
4. The measured IQ difference between Europeans and Ashkenazi Jews (as described by Cochran and Harpending, or Richard Lynn)
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These levels of IQ difference would unpack to make very substantial differences in the attainment of high level intellectual activities: just as, for example the proportion of successful scientists, writers, lawyers and chief executives that are produced is very different for an Ivy League college than for a big State University.
So, while there would be an overlap of something like 10-15 percent - and therefore many individual exceptions - the difference in intelligence between moderns and Victorians would readily be observable at the group level: and the decline would be obvious - at least to the Victorians!
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13 comments:
@Cantillonblog - thanks for pointing out the typo. I decided to change the RT unit from seconds to milliseconds, for ease of comparison - and apparently didn't quite finish the job...
But aren't I.Q. scores rising at about three points per decade?
@Jeremy - read the article I linked to.
It is probable that he was testing gentlemen, and people not far from gentle status.
I would guess that gentlemen and aristocrats were about one and half to two standard deviations above the general population.
@JAD - Silverman considers the class confounder - it doesn't seem to be the explanation.
Dr Charlton,
Could this "decline" have any correlation with the slaughter of the Great War and, perhaps, Spanish flu?
As far as I know, not that many chemicals were present in the environment after the War to influence the general intelligence, so a possible explanation could be the failure to reproduce.
@The most plausible factor is the differenitally lower reproduction of the most intelligent compared with the less intelligent - but the Great War very likely had a significant effect, becuase the slaughter was differentially of the most intelligent and able (and courageous) (i.e. junior officers had by far the highest mortality rate, and severe injuries too).
It's not hard to believe that on average people in the past were more intelligent. People now can barely handle complex grammar when spoken to them, much less create it, and that includes people rising in the ranks of administration, business, medicine and academia.
I have a feeling that while bgc is right about the world wars killing off many of the best, what has happened more is (a) the rising tide of lower caste people outbreeding everyone else and (b) neurosis, dysfunction, depression and hedonism removed many of the better possibilities, especially women, from the gene pool.
The death rate in Bomber Command in the Second World War was high and necessarily was concentrated on officers and NCOs.
Living in London for 12 years, it was several years ago that I started to get the sense that I was living in the ruins of a lost civilisation, like a barbarian after the fall of Rome. I kept seeing evidence of a former civilisation that seemed immeasurably superior in its capabilities and accomplishments to the culture in which I lived. This civilisation had apparently ended in the 1914-18 war.
I think the thing that really brought it home to me was witnessing the ruin of the tomb of Bazalgette, the man who built London's sewer system, surrounded by the mansions of London's multi-millionaires - http://www.taph.com/restoration/tomb-of-bazalgette-under-threat.html
http://www.flickr.com/photos/thevicardrains/5417085780/
Living in London for 12 years, it was several years ago that I started to get the sense that I was living in the ruins of a lost civilisation, like a barbarian after the fall of Rome.
I guess it is more similar to the late Roman Empire: prosperity is still there so the decline is not evident to everybody. But we are on our way to the demise to our civilization.
Check out the Flynn effect. IQ-measured intelligence has been rising steadily for the last 100 years, the whole time in which IQ tests have been widely used.
@John Cowan - check out what I actually wrote - this is the specific focus of the piece on reaction times!
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