Spearman's theory of intelligence proposes two primary factors: the general factor (often denoted as g) and specific factors (often denoted as s). These factors are part of a psychometric approach to understanding intelligence and were introduced by British psychologist Charles Spearman in the early 20th century.
General Factor (g): Spearman's g factor represents the general intelligence that underlies and influences a person's performance across different cognitive tasks. It is often referred to as "general mental ability" or "common intelligence." According to Spearman, g is responsible for the shared variance among different cognitive tests, indicating that individuals who perform well on one cognitive task are likely to perform well on other tasks as well. In other words, g reflects the overall cognitive capacity of an individual.
Specific Factors (s): In addition to the general factor (g), Spearman recognized that there are specific factors (s) that influence performance on individual cognitive tasks. These specific factors are unique to each particular task and account for the variability in performance that is not explained by the general factor. For example, specific factors might be related to mathematical ability, verbal comprehension, spatial reasoning, or memory.
Spearman's theory of intelligence, with its emphasis on the g factor, has been highly influential in the field of psychology and psychometrics. However, it is important to note that intelligence is a complex and multifaceted construct, and various theories and models of intelligence have been proposed over the years to capture its full breadth and diversity. While the g factor remains a prominent concept in the study of intelligence, other theories, such as Howard Gardner's multiple intelligences and Robert Sternberg's triarchic theory of intelligence, offer alternative perspectives on the nature of human cognitive abilities.