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Encyclopedia > General intelligence factor

The general intelligence factor (abbreviated g) is a controversial construct used in the field of psychology (see also psychometrics) to quantify what is common to the scores of all intelligence tests. The phrase "g theory" refers to hypotheses and results regarding g's biological nature, stability/malleability, relevance to real-world tasks, and other inquiries. Psychology is an academic or applied discipline involving the scientific study of mental processes such as perception, cognition, emotion, personality, behavior, and interpersonal relationships. ... Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, and personality traits. ... ...

Contents

History of g

An illustration of Spearman's two-factor intelligence theory. Each small oval is a hypothetical mental test. The blue areas show the variance attributed to s, and the purple areas the variance attributed to g.
An illustration of Spearman's two-factor intelligence theory. Each small oval is a hypothetical mental test. The blue areas show the variance attributed to s, and the purple areas the variance attributed to g.

Charles Spearman, an early psychometrician, found that schoolchildren's grades across seemingly unrelated subjects were positively correlated, and proposed that these correlations reflected the influence of a dominant factor, which he termed g for "general" intelligence. He developed a model where all variation in intelligence test scores can be explained by two factors. The first is the factor specific to an individual mental task: the individual abilities that would make a person more skilled at one cognitive task than another. The second is g, a general factor that governs performance on all cognitive tasks. Spearman's theory proved too simple, however, as it ignored group factors in test scores (corresponding to broad abilities such as spatial visualization, memory and verbal ability) that may also be found through factor analysis. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Charles Edward Spearman (September 10, 1863 - September 7, 1945) was an English psychologist known for work in statistics, as a pioneer of factor analysis, and for Spearmans rank correlation coefficient. ...


The accumulation of cognitive testing data and improvements in analytical techniques have preserved g's central role and led to the modern conception of g (Carroll 1993). A hierarchy of factors with g at its apex and group factors at successively lower levels, is espoused to be the most widely accepted model of cognitive ability[1]. Other models have also been proposed, and significant controversy attends g and its alternatives. Intelligence is the mental capacity to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn. ...


Mental testing and g

The abstraction of g stems from the observation that scores on all forms of cognitive tests correlate positively with one another. g can be derived as the principal factor from cognitive test scores using the method of principal components analysis or factor analysis. Positive linear correlations between 1000 pairs of numbers. ... In statistics, principal components analysis (PCA) is a technique for simplifying a dataset, by reducing multidimensional datasets to lower dimensions for analysis. ... Factor analysis is a statistical technique that originated in psychometrics. ...


The relationship of g to intelligence tests may be understood by an example. Irregular objects, such as the human body, are said to vary in "size". Yet no single measurement of a human body is obviously preferred to measure its "size" (although obviously the volume is). Instead, many and various measurements, such as those taken by a tailor, may be made. All of these measurements will be positively correlated with each other, and if one were to "add up" or combine all of the measurements, the aggregate would give a better description of an individual's size than any single measurement. The method of factor analysis allows this. The process is intuitively similar to taking the average of a sample of measurements of a single variable, but instead "size" is a summary measure of a sample of variables. g is like size, in that it is abstracted from various measures (of cognitive ability). Of course, variation in "size" does not fully account for all variation in the measurements of a human body. Factor analysis techniques are not limited to producing single factors, and an analysis of human bodies might produce (for example) two major factors, such as height and girth. However, the scores of tests of cognitive ability do in fact produce a primary dominant factor, g.


Tests of cognitive ability derive most of their validity from the extent to which they measure g. If quantifiable measures of the performance of a task correlate highly with g, it is said to be g-loaded. Creators of IQ tests, whose goals are generally to create highly reliable and valid tests, have thus made their tests as g-loaded as possible. Historically, this has meant dampening the influence of group factors by testing as wide a range of mental tasks as possible. However, tests such as Raven's Progressive Matrices are considered to be the most g-loaded in existence,[citation needed] even though Raven's is quite homogeneous in the types of tasks comprising it. IQ redirects here; for other uses of that term, see IQ (disambiguation). ... In psychometrics reliability is the accuracy of the scores of a measure. ... In logic, the form of an argument is valid precisely if it cannot lead from true premises to a false conclusion. ... Ravens Progressive Matrices are widely used non-verbal intelligence tests. ...


Elementary cognitive tasks (ECTs) also correlate strongly with g. ECTs are, as the name suggests, simple tasks that apparently require very little intelligence, but still correlate strongly with more exhaustive intelligence tests. Determining whether a light is red or blue and determining whether there are four or five squares drawn on a computer screen are two examples of ECTs. The answers to such questions are usually provided by quickly pressing buttons. Often, in addition to buttons for the two options provided, a third button is held down from the start of the test. When the stimulus is given to the subject, he removes his hand from the starting button to the button of the correct answer. This allows the examiner to determine how much time was spent thinking about the answer to the question (reaction time, usually measured in small fractions of second), and how much time was spent on physical hand movement to the correct button (movement time). Reaction time correlates strongly with g, while movement time correlates less strongly.[citation needed]


ECT testing has allowed quantitative examination of hypotheses concerning test bias, subject motivation, and group differences. By virtue of their simplicity, ECTs provide a link between classical IQ testing and biological inquiries such as fMRI studies. Functional Magnetic Resonance Imaging (or fMRI) describes the use of MRI to measure hemodynamic signals related to neural activity in the brain or spinal cord of humans or other animals. ...


Biological and genetic correlates of g

g has a large number of biological correlates. Strong correlates include mass of the prefrontal lobe, overall brain mass, and glucose metabolization rate within the brain. g correlates less strongly, but significantly, with overall body size. There is conflicting evidence regarding the correlation between g and peripheral nerve conduction velocity, with some reports of significant positive correlations, and others of no or even negative correlations. The subject of the inheritance of intelligence is the genetics of mental abilities. ... The frontal lobe is an area in the brains of vertebrates. ...


Current research suggests that broad-sense heritability of g is between 0.5 and 0.8, and narrow-sense heritability approximately 0.3, but the causal pathways are currently unknown. The heritability of most test performance is thus attributed to g. Heritability, as used professionally in genetics, has a very precise definition. ...


Brain size has long been known to be correlated with g (Jensen, 1998). Recently, an MRI study on twins (Thompson et al., 2001) showed that frontal gray matter volume was highly significantly correlated with g and highly heritable. A related study has reported that the correlation between brain size (reported to have a heritability of 0.85) and g is 0.4, and that correlation is mediated entirely by genetic factors (Posthuma et al., 2002). g has been observed in mice as well as humans (Matzel et al., 2003). The mri are a fictional alien species in the Faded Sun Trilogy of C.J. Cherryh. ...


g is probably limited by the channel capacity of short-term memory. Mental power, or the capacity C of short-term memory (measured in bits of information), is the product of the individual mental speed Ck of information processing (in bit/s) (see the external link below to the paper by Lehrl and Fischer (1990)), and the duration time D (in s) of information in short-term working memory, meaning the duration of memory span. Hence: Channel capacity, is the amount of discrete information that can be reliably transmitted over a channel. ... Short-term memory, sometimes referred to as primary, working, or active memory, is that part of memory which stores a limited amount of information for a few seconds. ... In general, information processing is the changing (processing) of information in any manner detectable by an observer. ... Working Memory is a theoretical framework within cognitive psychology that refers to the structures and processes used for temporarily storing and manipulating information. ...

C (bit) = Ck(bit/s) × D (s).

Social correlates of g

g positively correlates with conventional measures of success (income, academic achievement, job performance, career prestige) and negatively correlates with various social issues (school dropout, unplanned childbearing, poverty). IQ tests that measure a wide range of abilities do not predict much better than g. Scientific publishings of findings of differences in g between ethnic groups (see race and intelligence) have sparked public controversy. Normal distribution comparing races and ethnic groups with IQ among U.S. test subjects from 1981 (the most recent, large-scale, published adult IQ scores). ...


The Flynn effect and g

The Flynn effect describes a rise in IQ scores over time. There is no strong consensus as to whether rising IQ scores also reflect increases in g. In addition, there is recent evidence that the tendency for intelligence scores to rise has ended in some first world countries. [1] [2] [3] Statistical analyses of IQ subtest scores suggest a g-independent input to the Flynn effect (Wicherts et al. 2004). The Flynn effect is the rise of average Intelligence Quotient (IQ) test scores, an effect seen in most parts of the world, although at greatly varying rates. ... The terms First World, Second World, and Third World were used to divide the nations of Earth into three broad categories. ...


Challenges to g

The late Stephen Jay Gould voiced his objections to the concept of g, as well as intelligence testing in general, in his controversial book The Mismeasure of Man. It has been suggested that Darwinian Fundamentalism be merged into this article or section. ... This is a list of controversial non-fiction books aimed at the general reader which discuss controversial issues, or are (or were at the time of writing) controversial for other reasons. ... First edition (1981) of The Mismeasure of Man The Mismeasure of Man is a controversial, best-selling 1981 book written by the Harvard paleontologist Stephen Jay Gould (1941-2002). ...


Some researchers in artificial intelligence have argued that the science of mental ability can be thought of as "computationalism" and is "either silly or pointless," noting, "Mental ability tests measure differences in tasks that will soon be performed for all of us by computational agents. Such abilities probably have nothing to do with genius."(Bringsjord, 2000) . Hondas humanoid robot AI redirects here. ...


Intelligence expert Howard Gardner notes: It has been suggested that Naturalist Intelligence be merged into this article or section. ...

I do not believe that there is a single general talent, whether it be called intelligence, creativity or 'g'. I do not locate talents completely within the human skull, preferring to construe all accomplishments as an interaction between cognitive potentials on the one hand, and the resources and opportunities provided by the surrounding culture on the other....All intellectual and creative work takes place within some kind of social discipline, craft, or organized activity, termed a domain. Accordingly, there is no sense in which one can speak about a person as being intelligent, or creative, in general.

Philip Kitcher wrote in 1985:

Many scientists are now convinced that there is no single measure of intellectual ability - no unitary intelligence. Their suspicion of the concept of general intelligence is based on the view that various intellectual capacities are not well correlated. ....it is useful to continue to expose the myth of "general intelligence".

However, views that dismiss "g" as entirely fictional or irrelevant are controversial. Most psychometricians still recognize and employ "g" as a valid and coherent evaluation of human mental ability.


See also

Charles Edward Spearman (September 10, 1863 - September 7, 1945) was an English psychologist known for work in statistics, as a pioneer of factor analysis, and for Spearmans rank correlation coefficient. ... In psychometrics, fluid and crystallized intelligence (abbreviated gf and gc respectively) are factors of intelligence test scores originally described by Raymond Cattell. ... Intelligence is a property of mind that encompasses many related mental abilities, such as the capacities to reason, plan, solve problems, think abstractly, comprehend ideas and language, and learn. ... IQ tests are designed to give approximately this Gaussian distribution. ... Normal distribution comparing races and ethnic groups with IQ among U.S. test subjects from 1981 (the most recent, large-scale, published adult IQ scores). ...

References

  • Brand, C. (1996) The g Factor: General Intelligence and Its Implications. (depublished) [originally Wiley]. ISBN 0-471-96070-5
  • Bringsjord, S. (2000) In light of artificial intelligence, the science of mental ability is either silly or pointless. Psycoloquy: 11,#44. [2]
  • Carroll, J.B. (1993) Human Cognitive Abilities. Cambridge University Press.
  • Gardner, H. The relationship between early giftedness and later achievement. In Ciba Foundation. The origins and development of high ability. Ciba Foundation Symposium, 178 (pp. 175-186) 1993: Chichester, England: John Wiley & Sons.
  • Jensen, R.A. (1998) The g Factor. Praeger, Connecticut, USA.
  • Kitcher, P. (1985) Vaulting Ambition: Sociobiology and the Quest for Human Nature. Cambridge, Mass.: MIT Press.
  • Matzel, L.D., Han, Y.R., Grossman, H., Karnik, M.S., Patel, D., Scott, N., Specht, S.M., Gandhi, C.C. (2003) Individual differences in the expression of a "general" learning ability in mice. Journal of Neuroscience, 23(16):6423-33.
  • Posthuma, D., De Geus, E.J., Baare, W.F., Hulshoff Pol, H.E., Kahn, R.S., Boomsma, D.I. (2002) The association between brain volume and intelligence is of genetic origin. Nature Neuroscience, 5(2):83-4.
  • Thompson, P.M. et al. (2001). Genetic influences on brain structure. Nature Neuroscience, 4(12):1253-1258.
  • Wicherts, J.M., Dolan, C.V., Hessen, D.J., Oosterveld, P. Baal, G.C.M. van, Boomsma, D.I., & Span, M.M. (2004) Are intelligence tests measurement invariant over time? Investigating the nature of the Flynn effect. Intelligence, 32, 509-537 [3]

See:

The g Factor is a book by Arthur Jensen, explaining his views about the general intelligence factor (or g) and its apparent relation to race. Links Stalking the wild taboo - review of The g Factor in Mankind Quarterly, Vol. ...

External links

  • Inventory for Multiple Intelligences
  • The General Intelligence Factor PDF - Good article for laymen
  • The Basic Period of Individual Mental Speed, Underlying IQ
  • A Genomewide Scan for Genes Underlying General Cognitive Ability

  Results from FactBites:
 
General intelligence factor - Wikipedia, the free encyclopedia (1491 words)
The general intelligence factor (abbreviated g) is a widely accepted but controversial construct used in the field of psychology (see also psychometrics) to quantify what is common to the scores of all intelligence tests.
Factor analysis techniques are not limited to producing single factors, and an analysis of human bodies might produce (for example) two major factors, such as height and girth.
Their suspicion of the concept of general intelligence is based on the view that various intellectual capacities are not well correlated.
  More results at FactBites »

 
 

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