Global InformationIntelligence quotient information
| Intelligence quotient | |
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![[picture of an example IQ test item]](http://upload.wikimedia.org/wikipedia/commons/thumb/e/ec/Raven_Matrix.svg/290px-Raven_Matrix.svg.png) One kind of IQ test item, modelled after items in the Raven's Progressive Matrices test | |
| ICD-10-PCS | Z01.8 |
| ICD-9-CM | 94.01 |
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An intelligence quotient (IQ) is a total score derived from a set of standardised tests or subtests designed to assess human intelligence.[1] The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenzquotient, his term for a scoring method for intelligence tests at University of Breslau he advocated in a 1912 book.[2]
Historically, IQ was a score obtained by dividing a person's mental age score, obtained by administering an intelligence test, by the person's chronological age, both expressed in terms of years and months. The resulting fraction (quotient) was multiplied by 100 to obtain the IQ score.[3] For modern IQ tests, the raw score is transformed to a normal distribution with mean 100 and standard deviation 15.[4] This results in approximately two-thirds of the population scoring between IQ 85 and IQ 115 and about 2 percent each above 130 and below 70.[5][6]
Scores from intelligence tests are estimates of intelligence. Unlike, for example, distance and mass, a concrete measure of intelligence cannot be achieved given the abstract nature of the concept of "intelligence".[7] IQ scores have been shown to be associated with such factors as nutrition,[8][9][10] parental socioeconomic status,[11][12] morbidity and mortality,[13][14] parental social status,[15] and perinatal environment.[16] While the heritability of IQ has been investigated for nearly a century, there is still debate about the significance of heritability estimates[17][18] and the mechanisms of inheritance.[19]
IQ scores are used for educational placement, assessment of intellectual disability, and evaluating job applicants. In research contexts, they have been studied as predictors of job performance[20] and income.[21] They are also used to study distributions of psychometric intelligence in populations and the correlations between it and other variables. Raw scores on IQ tests for many populations have been rising at an average rate that scales to three IQ points per decade since the early 20th century, a phenomenon called the Flynn effect. Investigation of different patterns of increases in subtest scores can also inform current research on human intelligence.
- ^ Braaten, Ellen B.; Norman, Dennis (1 November 2006). "Intelligence (IQ) Testing". Pediatrics in Review. 27 (11): 403–408. doi:10.1542/pir.27-11-403. ISSN 0191-9601. PMID 17079505. Retrieved 22 January 2020.
- ^ Stern 1914, pp. 70–84 (1914 English translation), pp. 48–58 (1912 original German edition).
- ^ "intelligence quotient (IQ)". Glossary of Important Assessment and Measurement Terms. Philadelphia, PA: National Council on Measurement in Education. 2016. Archived from the original on 22 July 2017. Retrieved 1 July 2017.
- ^ Cite error: The named reference
Gottfredson2009pp31–32was invoked but never defined (see the help page). - ^ Neisser, Ulrich (1997). "Rising Scores on Intelligence Tests". American Scientist. 85 (5): 440–447. Bibcode:1997AmSci..85..440N. Archived from the original on 4 November 2016. Retrieved 1 December 2017.
- ^ Cite error: The named reference
Hunt2011p5was invoked but never defined (see the help page). - ^ Haier, Richard (28 December 2016). The Neuroscience of Intelligence. Cambridge University Press. pp. 18–19. ISBN 9781107461437.
- ^ Cusick, Sarah E.; Georgieff, Michael K. (1 August 2017). "The Role of Nutrition in Brain Development: The Golden Opportunity of the 'First 1000 Days'". The Journal of Pediatrics. 175: 16–21. doi:10.1016/j.jpeds.2016.05.013. PMC 4981537. PMID 27266965.
- ^ Saloojee, Haroon; Pettifor, John M (15 December 2001). "Iron deficiency and impaired child development". British Medical Journal. 323 (7326): 1377–1378. doi:10.1136/bmj.323.7326.1377. ISSN 0959-8138. PMC 1121846. PMID 11744547.
- ^ Qian, Ming; Wang, Dong; Watkins, William E.; Gebski, Val; Yan, Yu Qin; Li, Mu; Chen, Zu Pei (2005). "The effects of iodine on intelligence in children: a meta-analysis of studies conducted in China". Asia Pacific Journal of Clinical Nutrition. 14 (1): 32–42. ISSN 0964-7058. PMID 15734706.
- ^ Poh, Bee Koon; Lee, Shoo Thien; Yeo, Giin Shang; Tang, Kean Choon; Noor Afifah, Ab Rahim; Siti Hanisa, Awal; Parikh, Panam; Wong, Jyh Eiin; Ng, Alvin Lai Oon; SEANUTS Study Group (13 June 2019). "Low socioeconomic status and severe obesity are linked to poor cognitive performance in Malaysian children". BMC Public Health. 19 (Suppl 4): 541. doi:10.1186/s12889-019-6856-4. ISSN 1471-2458. PMC 6565598. PMID 31196019.
- ^ Galván, Marcos; Uauy, Ricardo; Corvalán, Camila; López-Rodríguez, Guadalupe; Kain, Juliana (September 2013). "Determinants of cognitive development of low SES children in Chile: a post-transitional country with rising childhood obesity rates". Maternal and Child Health Journal. 17 (7): 1243–1251. doi:10.1007/s10995-012-1121-9. ISSN 1573-6628. PMID 22915146. S2CID 19767926.
- ^ Markus Jokela; G. David Batty; Ian J. Deary; Catharine R. Gale; Mika Kivimäki (2009). "Low Childhood IQ and Early Adult Mortality: The Role of Explanatory Factors in the 1958 British Birth Cohort". Pediatrics. 124 (3): e380–e388. doi:10.1542/peds.2009-0334. PMID 19706576. S2CID 25256969.
- ^ Deary & Batty 2007.
- ^ Neisser et al. 1995.
- ^ Ronfani, Luca; Vecchi Brumatti, Liza; Mariuz, Marika; Tognin, Veronica (2015). "The Complex Interaction between Home Environment, Socioeconomic Status, Maternal IQ and Early Child Neurocognitive Development: A Multivariate Analysis of Data Collected in a Newborn Cohort Study". PLOS ONE. 10 (5): e0127052. Bibcode:2015PLoSO..1027052R. doi:10.1371/journal.pone.0127052. PMC 4440732. PMID 25996934.
- ^ Johnson, Wendy; Turkheimer, Eric; Gottesman, Irving I.; Bouchard, Thomas J. (August 2009). "Beyond Heritability". Current Directions in Psychological Science. 18 (4): 217–220. doi:10.1111/j.1467-8721.2009.01639.x. PMC 2899491. PMID 20625474.
- ^ Turkheimer 2008.
- ^ Devlin, B.; Daniels, Michael; Roeder, Kathryn (1997). "The heritability of IQ". Nature. 388 (6641): 468–71. Bibcode:1997Natur.388..468D. doi:10.1038/41319. PMID 9242404. S2CID 4313884.
- ^ Cite error: The named reference
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