- Neisser, Ulric, ed. The Rising Curve: Long-Term Gains in IQ
and Related Measures. Washington: American Psychological
Association, 1998. ISBN 1-55798-503-0.
- One of the most baffling phenomena in the social sciences
is the “Flynn Effect”. Political scientist James Flynn was among the
first to recognise the magnitude of increasing IQ scores over time and
thoroughly document that increase in more than a dozen nations around
the world. The size of the effect is nothing less than stunning: on
tests of “fluid intelligence” or g (problem-solving ability,
as opposed to acquired knowledge, vocabulary, etc.), Flynn's research
shows scores rising at least 3 IQ points per decade ever since testing
began—as much as one 15 point standard deviation per generation.
If you take these figures at face value and believe that IQ measures
what we perceive as intelligence in individuals, you arrive at any
number of absurdities: our grandparents' generation having a mean IQ of
70 (the threshold of retardation), an expectation that Einstein-level
intellect would be 10,000 times more common per capita today than in
his birth cohort, and that veteran teachers would perceive sons and
daughters of the students they taught at the start of their careers
as gifted to the extent of an IQ 115 student compared to a classmate
with an IQ of 100. Obviously, none of these are the case, and yet
the evidence for Flynn effect is overwhelming—the only reason few
outside the psychometric community are aware of it is that makers of
IQ tests periodically “re-standardise” their tests (in other words,
make them more difficult) in order to keep the mean score at 100.
Something is terribly wrong here: either IQ is a bogus measure (as
some argue), or it doesn't correlate with real-world intelligence,
or some environmental factor is increasing IQ test performance but
not potential for achievement or … well, who knows?
These are among the many theories advanced to explain this conundrum,
most of which are discussed in this volume, a collection of papers by
participants in a 1996 conference at Emory University on the evidence
for and possible causes of the Flynn effect, and its consequences for
long-term trends
in human intelligence. My conclusions from these papers are
threefold. First, the Flynn effect is real, having been demonstrated
as conclusively as almost any phenomenon in the social sciences.
Second, nobody has the slightest idea what is going on—theories
abound, but available data are insufficient to exclude any of numerous
plausible theories. Third, this is because raw data relating to these
questions is sparse and poorly suited to answering the questions with
which the Flynn effect confronts us. Almost every chapter laments
the shortcomings of the data set on which it was based or exhorts
“somebody” to collect data better suited to exploring details of the
Flynn effect and its possible causes. If human intelligence is indeed
increasing by one standard deviation per generation, this is one of
the most significant phenomena presently underway on our planet.
If IQ scores are increasing at this rate, but intelligence isn't,
then there's something very wrong with IQ tests or something terribly
pernicious which is negating the effects of the problem-solving
capability they claim to measure. Given the extent to which IQ tests
(or their close relatives: achievement tests such as the SAT, GRE,
etc.) determine the destiny of individuals, if there's something
wrong with these tests, it would be best to find out what's wrong
sooner rather than later.
July 2004 