Reading a road map upside-down, excelling at chess, and generating synonyms for "brilliant" may seem like three different skills. But each is thought to be a measurable indicator of general intelligence or "g," a construct that includes problem-solving ability, spatial manipulation, and language acquisition that is relatively stable across a person's lifetime.
IQ—or intelligence quotient—is the standard most widely used to assess general intelligence. IQ tests seek to measures a variety of intellectual skills that include verbal, non-verbal and spatial. Any person from any walk of life can be highly intelligent, and scoring high on one sub-test tends to correlate with high scores in other tests, though this is not always the case. IQ tests compare a person's performance with that of other people who are the same age—what’s known as a normative sample.
Research has shown that IQ is generally strongly correlated with positive life outcomes, including health and longevity, job performance, and adult income. It is also protective in ways that are not fully understood: People with high IQs seem to be at an advantage in coping with traumatic events—they are less likely to develop full-blown PTSD and more capable of overcoming it when they do—and may experience less rapid decline during the course of Alzheimer's Disease.
