The short answer to your question is "No, IQ doesn't really increase
with age." It's a little bit more complicated than that, however.
IQ can vary significantly (as much as 20 points, depending on any
number of external factors) over the course of your lifetime.
[http://www.brainy-child.com/expert/iq-score.shtml] This isn?t a
fast-occurring process, and isn?t predictably in one direction or the
other. Thus, while it is technically possible for your IQ to increase
by an appreciable amount (20 points marks more than a standard
deviation unit, which is very substantial indeed) over one?s lifetime,
it all averages out in the general populace. In general, your IQ in
childhood (past the age of 7 or so) is indicative of what your IQ will
be for the rest of your life.
Where the discussion becomes interesting, however, is in how one's IQ
*test* scores can change over time. You can train yourself to take IQ
tests, in much the same way you can train yourself to take the SAT.
Learning the nuances of the tests, and preparing yourself for the
appropriate types of questions and length of the test, can boost your
performance on IQ tests by a fair amount. This doesn't immediately
make sense: in the strictest sense of the word, you're not any
smarter, and your IQ isn't any higher. Yet, on paper, you're now
judged to be more intelligent!
I came across a few websites whose authority I found a little doubtful
[http://nicologic.free.fr/FAQ.htm, for instance], which insisted that
this increase in IQ scores shows increased intelligence; however, more
reputable sites point out that this phenomenon very closely resembles
the increase in IQ scores that has been manifesting itself for the
last century. Basically, average IQ scores have been increasing at
the rate of about 3 points per decade
[http://home.comcast.net/~neoeugenics/TRC.htm], but that doesn't
reflect increasing human intellect, or selective breeding (if it did,
Greek and Roman philosophers would have been morons, which we know
isn't true). Rather, the Flynn Effect (as it's known) is believed to
exist because of the increase in abstract problem solving ability
that's appeared in the last century. Since IQ scores are largely
based on these types of problem-solving abilities, an increase in this
type of ability creates an increase in IQ scores, even when people
aren't really becoming more intelligent. The same sort of thing
applies to an increase in IQ scores based on taking more IQ tests.
In short, IQ can be affected by any number of things (parenting,
poverty, environmental factors, and school attendance, among others),
but is statistically not likely to increase over one's lifetime.
One's IQ is, for the most part, unchanging after about the age of 7
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--bananarchy-ga ? Google Answers Researcher
Google search: iq change age
Followed links to encyclopedia articles cited therein
Decline or Increase in IQ Scores
The Rising Curve: Long-Term Gains in IQ and Related Measures
Frequently Asked Questions
Rising Scores on Intelligence Tests