General intelligence (g) is a highly practical ability that affects personal well-being in many aspects of life. This article reviews five key facts documenting its pervasive utility, and then illustrates how higher levels of intelligence enhance an individual's performance and well-being in four realms of daily life: work, daily self-maintenance, chronic illness, and accidents.
The first key fact is that people who do well on one mental test tend to perform well on all of them; that is, all mental tests correlate with one other. All measure mostly the same underlying ability factor, no matter what their manifest content or purpose. Mental abilities differ in their generality-specificity, and the general mental ability factor, g, is the most general of all. Second, high intelligence is expressed as a set of generic thinking skills that includes learning efficiently, reasoning well, thinking abstractly, and solving novel problems. These information-processing skills can be applied to virtually any kind of content in any context. Hence, third, everyday life continually requires individuals to learn and reason well. Fourth, ample evidence shows that general intelligence not only predicts many forms of success and well-being but usually does so better than socioeconomic status. More specific mental abilities add little to prediction beyond that contributed by g alone. Fifth, intelligence predicts performance better when tasks are more complex. Although higher intelligence is somewhat useful in many life arenas, it is particularly advantageous when jobs and daily tasks are more cognitively demanding. It is therefore important to know the distribution of task demands in different life areas.
Four life arenas illustrate how more cognitively demanding tasks put less intelligent individuals at greater risk. Job analysis research has repeatedly shown that the major distinction among jobs is their cognitive complexity, for example, their requirements for obtaining, analyzing, communicating, and applying oral, written, pictorial, and behavioral information. Consistent with this finding, intelligence predicts job performance progressively better in higher level jobs, and higher level jobs tend to recruit workers from higher levels of IQ.
Daily self-maintenance refers here to carrying out the many small reading, writing, and reasoning tasks that modern societies impose on their members, such as reading labels and filling out forms. Research shows that the difficulty of these functional literacy tasks, like that of jobs, rests on the complexity of their information processing demands, most generally, on the need to learn and reason. Functional literacy, like IQ itself, predicts various forms of socioeconomic success and failure.
Preventing and managing both chronic disease and accidental injury, the leading causes of death today, is a highly cognitive process. Studies of health literacy, which is learning and reasoning applied to health matters, show that less literate individuals have difficulty understanding and adhering to treatment regimens. Lower adherence predicts higher mortality. Accident prevention models reveal that it requires the same information processing skills that job analyses document as distinctive requirements of high-level, complex jobs: for instance, learning and recalling relevant information, identifying problem situations quickly, and reacting swiftly to unexpected situations. Health providers can reduce excess complexity in their communications and treatment regimens. They can also increase cognitive assistance when tasks are inherently complex, such as in the daily self-management of diabetes, hypertension, and asthma.