Saturday, October 29, 2011

Average Wordsum scores by age

As a frequent user of the GSS, I spend a lot of time looking at Wordsum scores. For those unfamiliar with the Wordsum test, it is a simple, 10 question definitional vocabulary test in which respondents earn one point for each word correctly identified from a multiple choice listing of potential synonyms (to see the actual test material, click here). I frequently employ it as a useful, though imperfect, proxy for IQ.

One reason for its imperfection is that rather than measure problem solving or deductive reasoning abilities, it tests for knowledge previously attained. Unlike an IQ test, Wordsum performance can be significantly improved by preparation, even if the specific words included in the test are unknown by the test taker ahead of time. According to my college psych 101 course, this demonstrates the differences between assessing a test-taker's fluid intelligence (which IQ tests mostly do) and crystallized intelligence (Wordsum). The two are highly correlated, however, which is why Wordsum results provide a useful approximation of IQ scores at the group level.

Crystallized intelligence is said to increase with time, as the accumulation of knowledge and experience builds. But at some point, the destructive forces of aging set in and begin attacking crystallized intelligence, the assault on fluid intelligence having been well under way for several decades.

By looking at average Wordsum scores by age range, the GSS allows one angle from which to look at the decline in crystallized intelligence and when it tends to begin. The following graph shows as much. To avoid racial confounding, non-white scores are excluded. For contemporary relevance, all results are from 2000 onward (n = 4,072):

Some noise notwithstanding, there is a steady increase in mean Wordsum scores from the late teens into the mid-sixties, at which point decline sets in. People tend to enter retirement when their minds are filled to the brim. Those who are forced to work into their retirement years are not afforded the luxury of going out on top. It must be depressing to experience a seepage of knowledge in one's chosen career after potentially having spent an entire professional lifetime accumulating it.

How nice it would be if we were able to reverse the declines aging inevitably (or evitably, perhaps?) brings.


Ed Tom Kowalsky said...

I find the information provided by that table to be rather hopeful. Hence, I would have thought the assault on all types of intelligent would have begun at a much earlier age than the late 60s. Heck, I've got at least a couple of decades worth of (relative) smarts left in me.

Mike Kenny said...

I wonder how intelligence and age affects politics, given at different times we have more or less of different age groups. If we have a lot of people in their early sixties in our society, it seems, based on your chart, we'll have a lot of crystalline intelligence floating around in our society. I wonder if you could estimate total fluid and total crystalline intelligence in a population, and see some interesting relationships. Say there's an unusually high ratio of fluid to crystalline intelligence in a population--would that population be more revolutionary? Or perhaps a population with an unusually high ratio of crystalline intelligence to fluid intelligence would be more conservative.

Jokah Macpherson said...

I wonder how much of the decline in the 60's is due to people retiring. I would think that not having to be intellectually agile on a daily basis at one's job would contribute to the decline. Use it or lose it as they say.

Audacious Epigone said...

Ed Tom Kowalsky,

Hell yes, three decades at least!


The conventional wisdom is that as people age, they tend to become less revolutionary--it's the college kids organizing on facebook who are in the streets, etc etc.

Speculating, I'd guess that relatively higher fluid intelligence tends to be associated with more progressive/revolutionary ideology, and relatively higher crystalline intelligence to be associated with less of both. Lots of clueless, quixotic bleeding hearts out to change the world in university classrooms drowning themselves in debt for degrees in the humanities and -studies, and hopefully a lot of baby boomers who are finally becoming aware of the unsustainable mess they've (primarily) put us in.


Good point. Is it that a decrease in intellectual demands leads to a decrease in intellectual vigor, or is it more of a propitious coincidence (based on our collective experience with the human condition, of course) that people tend to go out on top?

John said...

Could the Flynn effect be at work here? The evidence suggests that IQ scores stopped rising in about he 70s, so it will be interesting to compare this graph to one done 30 years from now.

Lover of Wisdom said...

The Flynn effect has little to no affect on scores pertaining to crystalized intelligence.

Unknown said...

Im not sure why anyone would think most iq tests are good neasures of fluid intelligence. They disproportionately measure crystallized intelligence

Anonymous said...

So we have a discussion of language skills that includes "they're" in lieu of their.