General factor of intelligence

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The General factor of intelligence (also general factor of intelligence , or g-factor of intelligence ) based on the statistical observation that many intelligence services more or less a general intelligence factor is involved. This justifies speaking of “the” intelligence in a simplistic way .

No other psychological construct can predict professional performance as precisely as the g-factor . However, it is only a rough guide for a person's intelligence profile. For example, if you require career counseling or neuropsychology , it often makes sense to distinguish between the characteristics of specific intelligence factors.

The idea of ​​a general mental ability that can be expressed in a single intelligence value has been controversial since the beginning of intelligence research. This was already the case in Charles Spearman's research on the two-factor theory of intelligence.


The British psychologist Charles Spearman founded the factor theory of intelligence in psychology in 1904 . By comparing different intelligence tests carried out on a group of test subjects, he discovered that almost all test modules within such a test correlate positively with one another.

The correlations were not high, but allowed the conclusion that there must be a generally valid factor that says something about a person's intelligence and that heredity plays a controversial role in its development. According to Spearman's theory, there is a connection between the various areas of ability of a person, and accordingly there must be a general “intelligence factor ”: the General Factor of Intelligence “g”. In addition to the General Factor of Intelligence , according to Spearman's two-factor theory of intelligence , every intelligence test also includes specific influencing variables.

Thurstone's investigation

Louis Leon Thurstone carried out further investigations in 1938: He extracted and compared the general factor of intelligence from six independent test batteries . The correlation of the g-factor of two test batteries was between +0.52 and +0.94. The relationship was not ideal, but it was positive. Thurstone concluded that general factors from the tests are consequently similar, but not identical. This finding formed the basis for Thurstone's factor theories .

Carroll's investigation

Compared to the two-factor theory of intelligence, various hierarchical factor models emerged. Several levels or layers of increasing generality were distinguished, for example “specific factors”, above and thus more general “group factors” and at the top the g-factor.

The most extensive analysis was carried out by John B. Carroll (1993). It was based on the data of well over 100,000 people. It also confirmed a hierarchical factor structure with a g-factor at the top. One level below it received factors of fluid and crystalline intelligence (after Raymond Bernard Cattell ). This Cattellian distinction becomes important when references are made to information psychological or neurobiological quantities. If the brain functions are reduced due to a lack of glucose or oxygen, the fluid intelligence is immediately lowered, while the crystalline intelligence is less dependent on disturbances.

Measurement of the g-factor

Specific intelligence tests (such as Raven's matrix test ) are often used to measure the g-factor. This procedure is justified by the fact that such intelligence tests for reasoning are the best indicator for the g-factor. However, it is regularly shown that with appropriate operationalization of intelligence, conclusive thinking is to be understood as a construct independent of the g-factor . Empirical studies on the suitability of specific intelligence tests as an operationalization of the g-factor come to the conclusion that Raven's matrix test alone is not sufficient to determine the g-factor.

An appropriate operationalization of the g-factor requires many different tasks, which differ in terms of cognitive requirements (e.g. reasoning, processing speed, memory) and content-related embedding (e.g. figural, numerical, verbal). If these requirements are met, then the g-factors of different intelligence test tasks correlate almost perfectly, i. H. can be regarded as practically identical.

An alternative approach to determining a general factor of intelligence is the short storage capacity of the Erlangen School of Information Psychology . According to this, the intelligence depends on the information processing speed and the memory span . However, this approach has so far not been able to establish itself in academic-psychological intelligence research.


  • John B. Carroll : Human cognitive abilities: A survey of factor-analytic studies . Cambridge University Press, Cambridge, UK 1993.
  • Raymond B. Cattell : Theory of Fluid and Crystallized Intelligence: A Critical Experiment. In: Educational Psychology. Volume 54, 1963, pp. 1-22.
  • Linda S. Gottfredson: The General Intelligence Factor . In: Scientific American . Exploring intelligence . tape 9 , no. 4 , 1998 ( online ).
  • Arthur R. Jensen : The g factor: The science of mental ability. Praeger, Westport, CT 1998.
  • Heiner Rindermann : What do international school achievement studies measure? School achievement, student skills, cognitive skills, knowledge, or general intelligence? In: Psychological Rundschau. Volume 57, 2006, pp. 69-86. (PDF; 165 kB)
  • Detlef H. Rost : Handbook of Intelligence. Beltz, Weinheim 2013.
  • Charles Spearman : General intelligence, objectively determined and measured. In: American Journal of Psychology. Volume 15, 1904, pp. 201-293. Classics in the History of Psychology - Spearman (1904) Index
  • Charles Spearman: The abilities of man. Macmillan, London 1927.
  • Rudolf Sponsel: General factors in intelligence tests: AID, BIS, HAWIE, IST70, LPS, SPM. 2009.

Web links

Individual evidence

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