The nature of intelligence is constantly being debated — are there different types of intelligence? Do IQ tests and standardised exams adequately capture capabilities commonly regarded as ‘intelligence’?

Most people could name someone who, despite being book smart, has poor judgment or sometimes struggles with everyday activities.

Research suggests that intelligence — in the commonly accepted sense measured by IQ tests — is not the same as good judgement. In fact, it’s a weaker predictor of real life events than is critical thinking.

A recently published paper has found that while both had a positive impact on life outcomes, people who scored higher on critical thinking were less likely to experience negative events than those who rate highly on standard intelligence tests.

Such tests measure things that might help you with rote learning, such as vocabulary questions, visuospatial puzzles to solve, digits to recall in order — both forwards and backwards — and a visual search for symbols. These are important, but are undoubtedly different to the everyday meaning of intelligence, which includes things like making well-reasoned decisions; supporting conclusions with evidence; thinking in an unbiased manner; avoiding common, well-documented biases in thinking, such as not considering regression to the mean; weighting evidence that conforms to an existing belief more heavily than evidence that does not; and being misled by the way information is framed.

Previous research has suggested that people with a high IQ are not always critical thinkers — they are no more likely than others to avoid common biases such as a preference for evidence that already supports their worldview.

The authors in this case asked a mix of university students and members of the community to fill out a series of questions about negative life experiences influenced by their own decisions, covering interpersonal relationships, work, finance, health and education, and varying in severity. Examples include paying late fees for a movie rental, spending time in gaol, and contracting a sexually transmitted disease due to unsafe sex. The more boxes a participant ticked, the poorer their judgement was taken to be.

They were then measured for critical thinking based on scenarios such as asking whether preschool should be made mandatory, given that children who attend preschool are better readers in first grade:

“The ideal response would indicate that these are correlational data and although it is possible that preschool attendance increased reading ability, it is also likely that families who could afford preschool provided other academic advantages for their children. After writing a one or two sentence response, respondents were shown a series of related facts and asked to rate the extent to which each fact would help them make an informed decision. For example, suppose we knew that the children who attended to preschool were, on average, twice as likely to come from a family earning over $75,000 a year than the children who did not attend preschool.

The researchers found that both higher IQ and more critical thinking were correlated with fewer negative life experiences, but critical thinking ability was a stronger predictor. They also discovered that combining the two was even more highly correlated to avoiding bad outcomes.

Improving critical thinking

This suggests that individuals should be better off if they are able to increase their critical thinking skills. It’s also good for one’s career, as a skill that is increasingly needed in a professionalising workforce — and that tends to be difficult to automate.

Some even argue a more intelligent population leads to better governance.

The good news is that it’s probably easier to cultivate critical thinking than IQ.

“There is considerable agreement that critical thinking skills can be enhanced, especially with specific instructional strategies designed for that purpose,” say the authors.

“We are optimistic that improving critical thinking and intelligence will have a positive impact on our everyday lives.”

Just as it’s difficult to define and measure what critical thinking is, it’s hard to pin down exactly what improves it. Critical thinking is not something you can just pick up by coasting along — it seems to require effort and structure. Studies tend to find that university is useful in developing critical faculties, though no specific course or subject area stands out. Some interventions specifically designed to improve critical thinking appear to work — in one study, biology students who were required to write collaborative essays, rather than just answer multiple choice questions, improved more. Benefits may also stem from things like being in a stimulating environment or reading at one’s own leisure.

It doesn’t necessarily takes years, though: some studies have detected a change in a few months among university students, for example.

The paper concludes with a call to arms:

“We are making a strong plea for more instruction in and attention to critical thinking skills. We can imagine a world where many more people think critically. Around the world, people are called upon to vote on a wide range of critical issues. The irrational (uncritical) voter is a threat to all of us, as are irrational politicians, business executives, and scientists. We believe that we can create a better future by enhancing critical thinking skills of citizens around the world. This optimism is tempered with the reality that so far, we only have data showing that individuals make fewer negative decisions in their personal lives when they are better thinkers, and can only imagine the impact of a world-wide increase in better thinking. We have nothing to lose by trying.”