Intelligence is a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, com- prehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings—“catching on,” “making sense” of things, or “figuring out” what to do.
This is a reasonable definition of intelligence. It includes a description of behaviors relating to attention, perception, and learning that we would certainly want to include as key aspects of intellectual functioning. What’s more, this definition captures how most people—especially in Western cultures conceptualize a “smart” person. When we talk about someone being “smarter” than someone else, we tend to invoke the notion of quick reasoning and problem solving. This conceptualization pervades Western media—from descriptions of presidential effectiveness to TV shows like Jeopardy and The Big Bang Theory.
But defining a term is one thing, measuring it is another. How can this definition be captured in the world? That is a much thornier issue. The framers of this definition argued that intelligence, as they defined it, can be measured, and IQ tests measure it well. Again, this is a reasonable statement. If you look at the characteristics of people who score high on IQ tests, they do tend to display the characteristics mentioned in this definition.
But if you consider the other ways people can display the characteristics in their definition, you realize how much more complex capturing intelligence is than merely administering an IQ test. Take reasoning. We can’t conclude that a person who doesn’t reason well in an IQ testing environment is incapable of displaying such skills. People reason much more competently when we relieve some of their working memory burden. We live in an age where we can easily unload much of the contents of our mind to an electronic device, leaving our working memory freer to manipulate symbols and solve personally relevant problems.
When we give people the chance to develop their cognitive skills in a broader environment and over a longer time span than a testing situation, they are capable of quite complex reasoning all across the IQ bell curve. Students who participate in Project Bright IDEA show a meaningful increase in a wide range of skills relating to novel and complex reasoning. When people with lower SAT scores are given a chance to capitalize on other characteristics, they meet or surpass the college academic performance of those selected with higher SAT scores. Prodigies, savants, and people with learning disabilities achieve extraordinary mental feats, despite, and even sometimes because of, their lower IQ scores. IQ test performance is not related to the social or clerical/conventional clusters of traits, or to creative achievement in a wide range of arts domains.
What about the ability to learn quickly from experience? Again, there are multiple ways someone can manifest these skills. The implicit learning system is capable of learning extraordinarily complex associations often better than explicit cognition. Additionally, once we are inspired and motivated to learn something, or we acquire a large database of domain-specific expertise, our reasoning can become quite sophisticated and learning of new content within the domain can proceed quite rapidly.
Why aren’t all of those mental routes considered forms of intelligence? Intelligence researchers count abstract reasoning, general cultural knowledge, and knowledge of arcane vocabulary words as intelligence, but many forms of reasoning, problem solving, and knowledge personally relevant to our lives don’t count? Why the heck not?
Another claim of the Wall Street Journal definition is that intelligence, as measured by IQ tests, is a “very general mental capability.” Here we immediately run into thorny territory again. Since IQ test scores are best thought of as the summary of a range of cognitive mechanisms, their statement surely reifies IQ. For the sake of advancing our discussion, however, let’s assume what they mean is that the cognitive skills that are most strongly related to g* (e.g., fluid reasoning, working memory, abstract relational complexity) are highly general because they facilitate the speed and efficiency of learning novel and complex information. This much is empirically true.
But there’s another sense in which I think they may mean “general.” The framers of the Wall Street Journal definition point out that “IQ is related, probably more so than any other single measurable human trait, to many important educational, occupational, economic, and social outcomes.” This is statistically true. g is part of a large “nexus” of positively correlated societal outcomes. g correlates positively with family income, socioeconomic status, school and occupational performance, military training assignments, law-abidingness, healthful habits, illness, and morality. In contrast, g is negatively correlated with welfare, psychopathology, crime, inattentiveness, boredom, delinquency, and poverty. The correlations exist. What remains far more ambiguous, in my view, is the interpretation of these correlations.
Tellingly, all of these outcomes are also correlated with one another, forming a large interconnected web of positively related variables. For instance, income is not only positively correlated with IQ, but is also positively correlated with amount of schooling, parental income, and parental status— all of which are individually also positively correlated with IQ. This makes it extremely difficult to disentangle all these variables from each other to figure out what’s causing what.
To be sure, IQ tests don’t simply measure family background. IQ and SAT scores are still correlated with important academic and societal outcomes even after taking into account socioeconomic status. But let’s not forget: IQ test performance is also an outcome—a person’s score on a brief test measured at one moment in time. As convenient as it would be for a person’s IQ score to measure something completely divorced from any learning, experience, and background, that’s not how IQ tests work, and that’s certainly not how the world works.
Any single person’s IQ test performance is itself a measure of many things in addition to their intellectual functioning across a range of cognition, including the person’s current levels of socioeconomic status, motivation, level of anxiety, self-belief, prior education, experience, opportunity, language, and many other things that are strongly connected to the very outcomes they are trying to predict.
The truth is, many factors operate together to produce a broad positive manifold of “desirable” social outcomes (e.g., high IQ, life expectancy, health, occupational success, etc.).* The path from IQ to academic achievement to occupational achievement to high achievement is far from direct. The rich get richer and the poor get poorer. Small differences multiply over the years to create large differences.
Ten-year-olds with good fluid reasoning skills and high executive functioning are a pleasure to teach, and they receive more challenging materials.They are expected to go to a good university. The positive expectations and increased intellectual enrichment only increase their chances of graduating from high school and getting into a prestigious university, which in turn will increase their chances of obtaining a “prestigious” job. Meanwhile, the child who early on finds school difficult, unrewarding, and perhaps even boring, is fed a less enriched curriculum, which exerts downward pressure on both expectations and achievement. As a result, the child is likely to get poorer and poorer grades, and leave school at the first opportunity.
But we must not forget that it’s educators and administrators who choose how schools should be structured, and what counts as a “good grade.” These are subjective decisions. What’s more, we are the ones who created a societal structure that establishes academic qualification as the mighty gatekeeper in life, and decided that the essential skills for attaining this qualification are those that are most highly correlated with g.†
The data don’t just “speak for themselves”.
*Technically defined as the first factor derived from a factor analysis of a diverse battery of cognitive tests, representing a diverse sample of the general population, explaining the largest
source of variance in the dataset (typically about 50 percent of the variance). See I. J. Deary, “Human Intelligence Differences: A Recent History,” Trends in Cognitive Sciences 5 (2001): 127–130.
*Importantly, and often underappreciated, if you get a large enough number of participants and variables, then even the slightest positive correlation between one variable and the next will be statistically significant without necessarily being practically significant.
†In fact, it’s quite likely that the cognitive skills that comprise g are positively correlated with each other in large part because we chose them to represent the foundation of education. In other words, we laid the groundwork for them to be positively correlated as they are mutu- ally developed in school (see Chapter 10).
This article was adapted from Chapter 13 of Ungifted: Intelligence Redefined