What Is Intelligence? Beyond the Flynn Effect

Very few scientists in any field have their names attached to well-known phenomena or tools of the trade, and psychology is no exception. Among the discipline's rare past examples, Skinner boxes and Freudian slips may well come to mind, but now the Flynn effect joins the list.

The term refers to the dramatic increases in intelligence test scores since the tests were developed around the turn of the past century, and its name recognises the central role that James R. Flynn, emeritus professor at the University of Otago in New Zealand, played in measuring and analysing these gains. The phenomenon has puzzled and intrigued psychologists for more than 20 years, and Flynn now brings his solution to the puzzle to the general public.

This book is fascinating in many ways, as much for what it isn't as for what it is. All of science teeters on the fine line between wishful thinking and objective empiricism, but the balance maintained in intelligence research is particularly wobbly and What Is Intelligence? is a good example. Egotistically, scientists want their own theories to be proven correct but, humanly, they also want the world to work the way they think it should. The evidence gets slotted where it will do the most good in one or, better yet, both those causes. This book has plenty of that.

I don't mean the heartbreaking examples of IQ tests with outdated norms used to condemn convicted criminals to death; I mean the rants on the conceptual imperialism, lapses of logic, and "g-ocentric tendencies" in those whose motivations and morals Flynn questions, and the judgmental statements, such as "Nothing is more certain than this", about propositions for which he later suggests tests.

Flynn warns readers upfront that the job of sorting through what is evidence and what is contention is theirs, and of course he is right. Ultimately, it is always the reader's job to evaluate what is being read. But some writers make this job a lot easier than this one does.

This is despite Flynn's statement at the beginning of the book that it is written for "anyone with a good education". In many ways this is absolutely true: the first half of the book is full of vivid analogies, many from sports, that clearly illustrate Flynn's conceptual explanations for the rising test scores that have seemed so paradoxical.

Together, the analogies provide lively reading and they should make their points in spades. Intelligence tests are the jewels in the crown of psychometrics because of the reliability of their scores in individuals and the high degree to which they predict the outcomes we would expect them to predict when administered to people of similar cultural background, at least when compared with other tests.

To many, this has meant that an intelligence test score says something absolute and fixed about a person, the way that Distance = Rate x Time specifies how an object moves through space here on Earth.

Error has always been recognised, of course, but it has been chalked up to test anxiety, caffeine and the vagaries of specifics in question and answer. Both the data Flynn is attempting to explain and his very plausible and readable explanations make it clear that the psychometric world is as relative as the physical, and psychologists will have to adjust as did physicists.

But when it comes to how Flynn thinks they should adjust, it is harder to see where he is going. Flynn makes much of what he presents as inappropriate inferences drawn from specific psychometric techniques such as factor analysis and quantitative genetics, and the results such as g loadings for specific IQ subtests and heritability estimates that they produce.

These are very technical issues, and Flynn does not present enough information here to understand how the inferences are drawn or the extent to which they are drawn consistently throughout the field, leaving the lay reader unable to follow his instruction to distinguish contention from evidence. This is too bad, because these are the issues on which rest his arguments about what intelligence is not.

This leaves the question of the book's title - what is intelligence? The book is full of insightful ideas about our measuring rods and the ways in which they tap the thing that matters: the brain's relative capacity to use memory and learning to adapt to the world as we have made it.

Read What Is Intelligence? for those ideas, because they are important. But by the time you reach the end you won't know much more about the thing that matters or how we might measure it than you did at the beginning.