Through intelligence, humans possess the cognitive abilities to learn, form concepts, understand, apply logic, and reason, including the capacities to recognize patterns, plan, innovate, solve problems, make decisions, retain information, and use language to communicate.
As a construct and measured by intelligence tests, intelligence is considered to be one of the most useful concepts used in psychology, because it correlates with many relevant variables, for instance the probability of suffering an accident, salary, and more.
According to a 2018 metastudy of educational effects on intelligence, education appears to be the “most consistent, robust, and durable method” known for raising intelligence.
A number of studies have shown a correlation between IQ and myopia. Some suggest that the reason for the correlation is environmental, whereby people with a higher IQ are more likely to damage their eyesight with prolonged reading, or the other way around whereby people who read more are more likely to reach a higher IQ, while others contend that a genetic link exists.
There is evidence that aging causes a decline in cognitive functions. In one cross-sectional study, various cognitive functions measured declines by about 0.8 in z-score from age 20 to age 50, the cognitive functions included speed of processing, working memory, and long-term memory.
A number of single-nucleotide polymorphisms in human DNA are correlated with intelligence.