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The g factor (also known as general intelligence, general mental ability, or general intelligence factor) is a construct developed in psychometric investigations of cognitive abilities and human intelligence.

Explanation:

For many years researchers have been attempting to understand the concept of human intelligence but could not perceive why some become bright thinkers, whereas others cannot grasp a piece of information. However, at the beginning of the 20th century, Charles Spearman started investigating human intelligence with the application of statistical analysis or factor analysis.

Factor analysis allows measure general abilities and overall performance, for example, people who succeed in a grammar test, may also thrive in a reading test.

According to the two-factor theory of intelligence, general intelligence underlies specific mental abilities that help to manifest general ones. The g-factor can be compared to athleticism, for instance, a person excels as a skilled figure skater, but they will not necessarily be great runners. However, it is evident that a person is fit enough to excel in other sports better.

Many intelligence tests allow measuring some variables or cognitive factors that create general intelligence. The first one is visual-spatial processing that includes combining pieces of a single object. The second is quantitative reasoning that deals with solving problems, including numbers.

The third is knowledge, which identifies the human ability to comprehend different topics. The fourth is fluid reasoning that checks the capacity of flexible thinking and problem-solving capacity. The final factor is working memory, which is based on the principle of repeating some things within a short period of time.