In 2002, the cognitive scientist Daniel Kahneman of Princeton University won the Nobel Prize in Economics for work done with his longtime collaborator Amos Tversky (who died in 1996). Their work had to do with judgment and decision-making — what makes our thoughts and actions rational or irrational. They explored how people make choices and assess probabilities, and uncovered basic errors that are typical in decision-making. The thinking errors they uncovered are not trivial mistakes in a parlor game. To be rational means to adopt appropriate goals, take the appropriate action given one’s goals and beliefs, and hold beliefs that are commensurate with available evidence. It means achieving one’s life goals using the best means possible. To violate the thinking rules examined by Kahneman and Tversky thus has the practical consequence that we are less satisfied with our lives than we might be. Research conducted in my own laboratory has indicated that there are systematic individual differences in the judgment and decision-making skills that Kahneman and Tversky studied.
Ironically, the Nobel Prize was awarded for studies of cognitive characteristics that are entirely missing from the most well-known mental assessment device in the behavioral sciences: intelligence tests. Scientists and laypeople alike tend to agree that “good thinking” encompasses sound judgment and decision-making — the type of thinking that helps us achieve our goals. Yet assessments of such good (rational) thinking are nowhere to be found on IQ tests. Intelligence tests measure important things, but they do not assess the extent of rational thought. This might not be such a grave omission if intelligence were a strong predictor of rational thinking. But my research group found just the opposite: it is a mild predictor at best, and some rational thinking skills are totally dissociated from intelligence.
To an important degree, intelligence tests determine the academic and professional careers of millions of people in many countries. Children are given intelligence tests to determine eligibility for admission to school programs for the gifted. Corporations and the military depend on assessment and sorting devices that are little more than disguised intelligence tests.
Perhaps some of this attention to intelligence is necessary, but what is not warranted is the tendency to ignore cognitive capacities that are at least equally important: The capacities that sustain rational thought and action.
Critics of intelligence tests have long pointed out that the tests ignore important parts of mental life, mainly non-cognitive domains such as socio-emotional abilities, empathy, and interpersonal skills. But intelligence tests are also radically incomplete as measures of cognitive functioning, which is evident from the simple fact that many people display a systematic inability to think or behave rationally despite having a more than adequate IQ. For a variety of reasons, we have come to overvalue the kinds of thinking skills that intelligence tests measure and undervalue other important cognitive skills, such as the ability to think rationally. Psychologists have studied the major classes of thinking errors that make people less than rational. They have studied people’s tendencies to show incoherent probability assessments; to be overconfident in knowledge judgments; to ignore the alternative hypothesis; to evaluate evidence with a “my side” bias; to show inconsistent preferences because of framing effects; to over-weigh short-term rewards at the expense of long-term well-being; to allow decisions to be affected by irrelevant context; and many others.