Books by Neisser, Ulric

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