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by tMcGrath
3158 days ago
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There's a reason the axes are left unlabeled in this graph. If you look at a paper that gives values over time for these quantities you'll find that this 'effect' mounts up to about 3 IQ points over the range discussed in the article in a population with an SD of 12 [0]. As a basis for discrimination, this is nonsense: on an individual basis you learn next to nothing about an individual's IQ if you know their age. Of course, there may be better studies out there - I'm not an expert and so don't know of them. [0] http://www.sciencedirect.com/science/article/pii/08876177950... |
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It looks like fluid IQ peaks around 24 then rapidly declines until around 30. Between the 30 and 50 the decline somewhat levels off.. i.e, doesn't decline a much during that period and crystallized IQ increases slightly.
After 50, fluid IQ resumes a rapid decline at a steady rate until about 75 where it really begins to tank.
But you are right, for the timescale in question the IQ difference is pretty small. I'm sure everyone reading this is very smart so a difference of 3 or 4 points shouldn't concern them all that much :)
A couple of things I wonder about, lack of physical activity (I've read) helps hasten cognitive decline. Sitting in a chair for 20 years as opposed to being active for 20 years, wonder what difference it makes? Perhaps sitting in a chair and thinking more than offsets the difference?
Also I wonder about so many world leaders being well over 50 or 60, for example Supreme Court Justices in their 80's. What would happen if a long resume didn't matter so much and we had a slightly younger (not 24 god forbid!) group running government? Just a hypothetical question.
But from that graph, if you are going to hire a 30 year old over a 45 year old (because "younger people are smarter") it appears you'd actually be better off with the 45 year old in sum (crystallized and fluid) intelligence plus whatever experience bonus.