View source for Intelligence

{{Short description|Ability to perceive, infer, retain or apply information}}
{{About||the human faculty of thinking and understanding|Intellect|human intelligence|Human intelligence|other uses}}
{{Use dmy dates|date=August 2019}}
{{Intelligence}}
{{Psychology sidebar}}

'''Intelligence''' has been defined in many ways: the capacity for [[abstraction]], [[logic]], [[understanding]], [[self-awareness]], [[learning]], [[emotional knowledge]], [[reason]]ing, [[planning]], [[creativity]], [[critical thinking]], and [[problem-solving]]. It can be described as the ability to perceive or infer [[information]] and to retain it as [[knowledge]] to be applied to adaptive behaviors within an environment or context.<ref>Sharma, Radha R. (2008). ''Emotional Intelligence from 17th Century to 21st Century: Perspectives and Directions for Future Research.'' Sage Journals. Vol. 12.</ref>

The term rose to prominence during the early 1900s.{{vague|date=March 2025|reason=early 1900s decade or early 20th century?}}<ref>White, Margaret B. & Hall, Alfred E. (1980). ''An overview of intelligence testing.'' Phi Delta Kappa International. Vol. 58, No. 4, pp. 210-216</ref><ref>Buxton, Claude E. (1985). ''Influences in Psychology: Points of View in the Modern History of Psychology.'' Academic Press.</ref> Most [[psychologist]]s believe that intelligence can be divided into various domains or competencies.<ref name=":5" />

Intelligence has been long-studied in [[human]]s, and across numerous disciplines. It has also been observed in the [[Animal cognition|cognition of non-human animals]].<ref name="Shettleworth">{{cite book |title=Cognition, Evolution and Behavior |vauthors=Shettleworth SJ |publisher=Oxford Press |year=2010 |edition=2ND |location=New York}}</ref> Some researchers have suggested that [[Plant|plants]] exhibit forms of intelligence, though this remains controversial.<ref>{{Cite journal |last1=Parise |first1=André Geremia |last2=Gaglianob |first2=Monica |last3=Souza |first3=Gustavo Maia |date=3 January 2020 |title=Extended cognition in plants: is it possible? |journal=Plant Signaling & Behavior |volume=15 |issue=2|doi=10.1080/15592324.2019.1710661 |pmid=31900033 |pmc=7053971 |bibcode=2020PlSiB..1510661P }}</ref><ref name=":2" /><ref name=":3" />

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== Etymology ==
{{Main|Nous}}
The word ''[[wikt:intelligence#English|intelligence]]'' derives from the Latin [[noun]]s ''[[wikt:intelligentia|intelligentia]]'' or ''[[wikt:intellectus|intellēctus]]'', which in turn stem from the verb ''[[wikt:intelligere|intelligere]]'', to comprehend or perceive. In the [[Middle Ages]], the word ''intellectus'' became the scholarly technical term for understanding and a translation for the Greek philosophical term ''nous''. This term, however, was strongly linked to the [[metaphysics|metaphysical]] and [[cosmology|cosmological]] theories of [[teleology|teleological]] [[scholasticism]], including theories of the immortality of the soul, and the concept of the [[active intellect]] (also known as the active intelligence). This approach to the study of nature was strongly rejected by  [[early modern philosophy|early modern philosophers]] such as [[Francis Bacon]], [[Thomas Hobbes]], [[John Locke]], and [[David Hume]], all of whom preferred "understanding" (in place of "''intellectus''" or "intelligence") in their English philosophical works.<ref>{{Cite book |last=Maich|page=305|title=A Hobbes Dictionary|first=Aloysius|publisher=Blackwell|year=1995}}</ref><ref>{{Cite book|last=Nidditch|first=Peter|chapter=Foreword|page=xxii|publisher=Oxford University Press|title=An Essay Concerning Human Understanding}}</ref> Hobbes for example, in his Latin ''[[De Corpore]]'', used "''intellectus intelligit''", translated in the English version as "the understanding understandeth", as a typical example of a logical [[absurdity]].<ref>{{cite web|url=https://archive.org/details/thomhobbesmalme03molegoog|archive-url=https://web.archive.org/web/20131105204954/http://www.archive.org/stream/thomhobbesmalme03molegoog|url-status=dead|title=Opera philosophica quæ latine scripsit omnia, in unum corpus nunc primum collecta studio et labore Gulielmi Molesworth ..|first1=Thomas|last1=Hobbes|first2=William|last2=Molesworth|date=15 February 1839|archive-date=5 November 2013|publisher=Londoni, apud Joannem Bohn|via=Internet Archive}}</ref> "Intelligence" has therefore become less common in English language philosophy, but it has later been taken up (with the scholastic theories that it now implies) in more contemporary [[psychology]].<ref>This paragraph almost verbatim from {{cite book|editor-last1=Goldstein|editor-first1=Sam|editor-last2=Princiotta|editor-first2=Dana|editor-last3=Naglieri|editor-first3=Jack A.|title=Handbook of Intelligence: Evolutionary Theory, Historical Perspective, and Current Concepts|date=2015|publisher=Springer|location=New York, Heidelberg, Dordrecht, London|isbn=978-1-4939-1561-3|page=3}}</ref>

== Definitions ==
There is controversy over how to define intelligence. Scholars describe its constituent abilities in various ways, and differ in the degree to which they conceive of intelligence as quantifiable.<ref name="LeggHutter2007">{{cite book
 |author1=S. Legg |author2=M. Hutter | chapter =        A Collection of Definitions of Intelligence
 | title =    Advances in Artificial General Intelligence: Concepts, Architectures and Algorithms
 | volume =       157
 | pages =       17–24
 | url =          http://dl.acm.org/citation.cfm?id=1565458
|isbn=978-1586037581 |year=2007 |publisher=IOS Press }}</ref>

A consensus report called ''[[Intelligence: Knowns and Unknowns]]'', published in 1995 by the Board of Scientific Affairs of the [[American Psychological Association]], states:
{{Blockquote|Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person's intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena. Although considerable clarity has been achieved in some areas, no such conceptualization has yet answered all the important questions, and none commands universal assent. Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen, somewhat different, definitions.<ref name=Neisser1998>{{cite journal |last1=Neisser |first1=Ulrich |last2=Boodoo |first2=Gwyneth |last3=Bouchard |first3=Thomas J. |last4=Boykin |first4=A. Wade |last5=Brody |first5=Nathan |last6=Ceci |first6=Stephen J. |last7=Halpern |first7=Diane F. |last8=Loehlin |first8=John C. |last9=Perloff |first9=Robert |last10=Sternberg |first10=Robert J. |last11=Urbina |first11=Susana |author-link1=Ulrich Neisser |author-link10=Robert Sternberg |title=Intelligence: Knowns and unknowns |journal=American Psychologist |issn=0003-066X |volume=51 |issue=2 |pages=77–101 |year=1996 |url=http://psych.colorado.edu/~carey/pdfFiles/IQ_Neisser2.pdf |access-date=9 October 2014 |doi=10.1037/0003-066x.51.2.77 |url-status=live |archive-url=https://web.archive.org/web/20160328064747/http://psych.colorado.edu/~carey/pdfFiles/IQ_Neisser2.pdf |archive-date=28 March 2016 |df=dmy-all }}</ref>}}

[[Psychologists]] and [[learning]] researchers also have suggested definitions of intelligence such as the following:
{| class="wikitable"
|-
! style="width:140px;"| Researcher
! Quotation
|-
| [[Alfred Binet]]
| Judgment, otherwise called "good sense", "practical sense", "initiative", the faculty of adapting one's self to circumstances ... auto-critique.<ref name=Binet1905>{{Cite book |last=Binet |first=Alfred |chapter=New methods for the diagnosis of the intellectual level of subnormals |title=The development of intelligence in children: The Binet-Simon Scale |others=E.S. Kite (Trans.) |location=Baltimore |publisher=Williams & Wilkins |year=1916 |orig-date=1905 |pages=37–90 |chapter-url=http://psychclassics.asu.edu/Binet/binet1.htm |quote=originally published as Méthodes nouvelles pour le diagnostic du niveau intellectuel des anormaux. L'Année Psychologique, 11, 191–244 |access-date=14 August 2010 |archive-date=19 June 2010 |archive-url=https://web.archive.org/web/20100619145626/http://psychclassics.asu.edu/Binet/binet1.htm |url-status=dead }}</ref>
|-
| [[David Wechsler]]
| The aggregate or global capacity of the individual to act purposefully, to think rationally, and to deal effectively with his environment.<ref>{{Cite book |last=Wechsler |first=D |author-link=David Wechsler |title=The measurement of adult intelligence |publisher=Williams & Wilkins |location=Baltimore |year=1944 |isbn=978-0-19-502296-4 |oclc=219871557}}</ref>
|-
| [[Lloyd Humphreys]]
| "...the resultant of the process of acquiring, storing in memory, retrieving, combining, comparing, and using in new contexts information and conceptual skills".<ref>{{Cite journal |author=Humphreys, L. G. |year=1979 |title=The construct of general intelligence |journal=Intelligence |volume=3 |pages=105–120 |doi=10.1016/0160-2896(79)90009-6 |issue=2}}</ref>
|-
|[[Howard Gardner]]
|To my mind, a human intellectual competence must entail a set of skills of [[problem solving]]—enabling the individual to resolve genuine problems or difficulties that he or she encounters and, when appropriate, to create an effective product—and must also entail the potential for finding or creating problems—and thereby laying the groundwork for the acquisition of new knowledge.<ref name="isbn0465025102">{{Cite book |title=Frames of mind: The theory of multiple intelligences |publisher=Basic Books |location=New York |year=1993 |isbn=978-0-465-02510-7 |oclc=221932479 |url=https://archive.org/details/framesofmindtheo00gard }}</ref>
|-
|[[Robert Sternberg]] & William Salter
|[[Goal-oriented|Goal-directed]] adaptive behavior.<ref name="isbn0521296870">{{Cite book |author=Sternberg RJ |author-link=Robert Sternberg |author2=Salter W |title=Handbook of human intelligence |publisher= Cambridge University Press |location=Cambridge, UK |year=1982 |isbn=978-0-521-29687-8 |oclc=11226466}}</ref>
|-
|[[Reuven Feuerstein]]
|The theory of Structural Cognitive Modifiability describes intelligence as "the unique propensity of human beings to change or modify the structure of their cognitive functioning to adapt to the changing demands of a life situation".<ref>Feuerstein, R., Feuerstein, S., Falik, L & Rand, Y. (1979; 2002). Dynamic assessments of cognitive modifiability. ICELP Press, Jerusalem: Israel; Feuerstein, R. (1990). The theory of structural modifiability. In B. Presseisen (Ed.), Learning and thinking styles: Classroom interaction. Washington, DC: National Education Associations</ref>
|-
|[[Shane Legg]] & [[Marcus Hutter]]
| A synthesis of 70+ definitions from psychology, philosophy, and AI researchers: "Intelligence measures an agent's ability to achieve goals in a wide range of environments",<ref name="LeggHutter2007"/> which has been mathematically formalized.<ref name="LeggHutter2007b">{{cite journal
 |author1=S. Legg |author2=M. Hutter | title =        Universal Intelligence: A Definition of Machine Intelligence
 | volume =       17
 | number =       4
 | journal =      Minds and Machines
 | pages =        391–444
 | year =         2007
 | doi =          10.1007/s11023-007-9079-x
| arxiv =0712.3329|bibcode=2007arXiv0712.3329L |s2cid=847021 }}</ref>
|-
|[[Alexander Wissner-Gross]]
| F = T ∇ S<math>_\tau</math><ref>{{cite web |url=https://www.ted.com/talks/alex_wissner_gross_a_new_equation_for_intelligence |title=TED Speaker: Alex Wissner-Gross: A new equation for intelligence |date=6 February 2014 |publisher=TED.com |access-date=2016-09-07 |url-status=live |archive-url=https://web.archive.org/web/20160904234706/http://www.ted.com/talks/alex_wissner_gross_a_new_equation_for_intelligence |archive-date=4 September 2016  }}</ref>
"Intelligence is a force, F, that acts so as to maximize future freedom of action. It acts to maximize future freedom of action, or keep options open, with some strength T, with the diversity of possible accessible futures, S, up to some future time horizon, τ. In short, intelligence doesn't like to get trapped".
|}

== Human ==
{{Main|Human intelligence}}

Human intelligence is the intellectual power of humans, which is marked by complex [[cognition|cognitive]] feats and high levels of [[motivation]] and [[self-awareness]].<ref>{{cite book|last1=Tirri, Nokelainen|title=Measuring Multiple Intelligences and Moral Sensitivities in Education|publisher=Springer|isbn=978-94-6091-758-5|url=https://www.springer.com/gp/book/9789460917585|url-status=live|archive-url=https://web.archive.org/web/20170802041535/http://www.springer.com/gp/book/9789460917585|archive-date=2 August 2017|year=2011|series=Moral Development and Citizenship Education}}</ref><ref>{{cite journal |last1=Colom |first1=Roberto |date=Dec 2010 |title=Human intelligence and brain networks |journal=Dialogues Clin. Neurosci. |volume=12 |issue=4 |pages=489–501 |doi=10.31887/DCNS.2010.12.4/rcolom |pmc=3181994 |pmid=21319494}}</ref> Intelligence enables humans to remember descriptions of things and use those descriptions in future behaviors. It gives humans the cognitive abilities to [[learning|learn]], [[Concept learning|form concepts]], [[understanding|understand]], and [[reason]], including the capacities to [[pattern recognition|recognize patterns]], innovate, [[planning|plan]], [[problem solving|solve problems]], and employ [[language]] to [[Human communication|communicate]]. These cognitive abilities can be organized into frameworks like [[Fluid and crystallized intelligence|fluid vs. crystallized]] and the Unified Cattell-Horn-Carroll model,<ref name=":5">{{Citation |last1=Stanek |first1=Kevin C. |title=Taxonomies and Compendia of Cognitive Ability and Personality Constructs and Measures Relevant to Industrial, Work and Organizational Psychology |date=2018 |url=http://sk.sagepub.com/reference/the-sage-handbook-of-industrial-work-and-org-psychology-vol1/i3345.xml |work=The SAGE Handbook of Industrial, Work and Organizational Psychology: Personnel Psychology and Employee Performance |pages=366–407 |access-date=2024-01-08 |place=1 Oliver's Yard, 55 City Road London EC1Y 1SP |publisher=SAGE Publications Ltd |doi=10.4135/9781473914940.n14 |isbn=978-1-4462-0721-5 |last2=Ones |first2=Deniz S.|url-access=subscription }}</ref> which contains abilities like fluid reasoning, perceptual speed, verbal abilities, and others.

Intelligence is different from [[learning]]. Learning refers to the act of retaining facts and information or abilities and being able to recall them for future use. Intelligence, on the other hand, is the cognitive ability of someone to perform these and other processes. 

=== Intelligence quotient (IQ) ===
{{Main|Intelligence quotient}}

There have been various attempts to quantify intelligence via [[psychometric]] testing. Prominent among these are the various [[Intelligence quotient|Intelligence Quotient]] (IQ) tests, which were first developed in the early 20th century to screen children for [[intellectual disability]].<ref name=":6">{{Cite book |last=Kaufman |first=Alan S. |title=IQ Testing 101 |publisher=Springer |year=2009 |isbn=978-0-8261-0629-2}}</ref> Over time, IQ tests became more pervasive, being used to screen immigrants, military recruits, and job applicants.<ref>{{cite journal |last1=Richardson |first1=John T. E. |year=2003 |title=Howard Andrew Knox and the origins of performance testing on Ellis Island, 1912-1916 |journal=History of Psychology |volume=6 |issue=2 |pages=143–70 |doi=10.1037/1093-4510.6.2.143 |pmid=12822554}}</ref> As the tests became more popular, belief that IQ tests measure a fundamental and unchanging attribute that all humans possess became widespread.<ref name=":6" /> 

An influential theory that promoted the idea that IQ measures a fundamental quality possessed by every person is the theory of [[G factor (psychometrics)|General Intelligence, or ''g'' factor]].<ref>{{Cite journal |last=Schlinger |first=Henry D. |date=2003 |title=The myth of intelligence |url=https://psycnet.apa.org/record/2003-01443-003 |journal=The Psychological Record |volume=53 |issue=1 |pages=15–32}}</ref> The ''g'' factor is a construct that summarizes the [[Correlation|correlations]] observed between an individual's scores on a range of cognitive tests. 

Today, most psychologists agree that IQ measures at least some aspects of human intelligence, particularly the ability to thrive in an academic context.<ref name="Weiten" /> However, many psychologists question the [[Validity (statistics)|validity]] of IQ tests as a measure of intelligence as a whole.<ref name="Weiten">{{cite book |url=https://books.google.com/books?id=ALkaCgAAQBAJ&pg=PT331 |title=Psychology: Themes and Variations |vauthors=Weiten W |publisher=[[Cengage Learning]] |year=2016 |isbn=978-1305856127 |page=281 |quote=IQ tests are valid measures of the kind of intelligence necessary to do well in academic work. But if the purpose is to assess intelligence in a broader sense, the validity of IQ tests is questionable.}}</ref><ref name=":4">{{Cite journal|last=Bouchard|first=Thomas J.|date=1982|title=Review of The Intelligence Controversy|url=https://www.jstor.org/stable/1422481|journal=The American Journal of Psychology|volume=95|issue=2|pages=346–349|doi=10.2307/1422481|jstor=1422481|issn=0002-9556|url-access=subscription}}</ref>

There is debate about the [[heritability of IQ]], that is, what proportion of differences in IQ test performance between individuals are explained by [[Genetics|genetic]] or [[Biophysical environment|environmental]] factors.<ref name="Bouchard2013W">{{cite journal|last1=Bouchard|first1=Thomas J.|date=7 August 2013|title=The Wilson Effect: The Increase in Heritability of IQ With Age|journal=Twin Research and Human Genetics|volume=16|issue=5|pages=923–930|doi=10.1017/thg.2013.54|pmid=23919982|s2cid=13747480|doi-access=free}}</ref><ref name="pmid12486697">{{cite journal |last1=Bouchard |first1=Thomas J. |last2=McGue |first2=Matt |title=Genetic and environmental influences on human psychological differences |journal=Journal of Neurobiology |date=January 2003 |volume=54 |issue=1 |pages=4–45 |doi=10.1002/neu.10160 |pmid=12486697 |doi-access=free }}</ref> The scientific consensus is that genetics does not explain [[Race and intelligence|average differences in IQ test performance between racial groups.]]<ref>{{Cite journal |last1=Bird |first1=Kevin |last2=Jackson |first2=John P. |last3=Winston |first3=Andrew S. |date=2024 |title=Confronting Scientific Racism in Psychology: Lessons from Evolutionary Biology and Genetics |url=https://psycnet.apa.org/doiLanding?doi=10.1037%2Famp0001228 |journal=American Psychologist |volume=79 |issue=4 |pages=497–508 |doi=10.1037/amp0001228 |pmid=39037836 |quote=Recent articles claim that the folk categories of race are genetically meaningful divisions, and that evolved genetic differences among races and nations are important for explaining immutable differences in cognitive ability, educational attainment, crime, sexual behavior, and wealth; all claims that are opposed by a strong scientific consensus to the contrary.|url-access=subscription }}</ref><ref name=":02">{{cite journal |last1=Nisbett |first1=Richard E. |author-link1=Richard E. Nisbett |last2=Aronson |first2=Joshua |last3=Blair |first3=Clancy |last4=Dickens |first4=William |last5=Flynn |first5=James |author-link5=Jim Flynn (academic) |last6=Halpern |first6=Diane F. |author-link6=Diane F. Halpern |last7=Turkheimer |first7=Eric |date=2012 |title=Group differences in IQ are best understood as environmental in origin |url=http://people.virginia.edu/~ent3c/papers2/Articles%20for%20Online%20CV/Nisbett%20(2012)%20Group.pdf |url-status=live |journal=American Psychologist |volume=67 |pages=503–504 |doi=10.1037/a0029772 |issn=0003-066X |pmid=22963427 |archive-url=https://web.archive.org/web/20150123114230/http://people.virginia.edu/~ent3c/papers2/Articles%20for%20Online%20CV/Nisbett%20(2012)%20Group.pdf |archive-date=23 January 2015 |access-date=22 July 2013 |number=6}}</ref><ref name=":22">{{Cite journal |last1=Ceci |first1=Stephen |last2=Williams |first2=Wendy M. |date=1 February 2009 |title=Should scientists study race and IQ? YES: The scientific truth must be pursued |journal=Nature |volume=457 |issue=7231 |pages=788–789 |bibcode=2009Natur.457..788C |doi=10.1038/457788a |pmid=19212385 |s2cid=205044224 |quote=There is an emerging consensus about racial and gender equality in genetic determinants of intelligence; most researchers, including ourselves, agree that genes do not explain between-group differences. |doi-access=free}}</ref>

=== Emotional ===
{{Main|Emotional intelligence}}

Emotional intelligence is thought to be the ability to convey [[emotion]] to others in an understandable way as well as to read the emotions of others accurately.<ref name=":0">{{Cite journal|last1=Salovey|first1=Peter|last2=Mayer|first2=John D.|date=March 1990|title=Emotional Intelligence|url=http://journals.sagepub.com/doi/10.2190/DUGG-P24E-52WK-6CDG|journal=Imagination, Cognition and Personality|language=en|volume=9|issue=3|pages=185–211|doi=10.2190/DUGG-P24E-52WK-6CDG|hdl=10654/36316|s2cid=219900460|issn=0276-2366|hdl-access=free|url-access=subscription}}</ref> Some theories imply that a heightened emotional intelligence could also lead to faster generating and processing of emotions in addition to the accuracy.<ref>{{Cite journal|last1=Mayer|first1=John D.|last2=Salovey|first2=Peter|date=1993-10-01|title=The intelligence of emotional intelligence|url=https://dx.doi.org/10.1016%2F0160-2896%2893%2990010-3|journal=Intelligence|language=en|volume=17|issue=4|pages=433–442|doi=10.1016/0160-2896(93)90010-3|issn=0160-2896|url-access=subscription}}</ref> In addition, higher emotional intelligence is thought to help us manage emotions, which is beneficial for our problem-solving skills. Emotional intelligence is important to our [[mental health]] and has ties to social intelligence.<ref name=":0" />

=== Social ===
{{Main|Social intelligence}}

Social intelligence is the ability to understand the [[social cue]]s and motivations of others and oneself in social situations. It is thought to be distinct from other types of intelligence, but has relations to emotional intelligence. Social intelligence has coincided with other studies that focus on how we make judgements of others, the accuracy with which we do so, and why people would be viewed as having positive or negative [[social character]]. There is debate as to whether or not these studies and social intelligence come from the same theories or if there is a distinction between them, and they are generally thought to be of two different [[School of thought|schools of thought]].<ref name=":1">{{Cite journal|last1=Walker|first1=Ronald E.|last2=Foley|first2=Jeanne M.|date=December 1973|title=Social Intelligence: Its History and Measurement|url=http://journals.sagepub.com/doi/10.2466/pr0.1973.33.3.839|journal=Psychological Reports|language=en|volume=33|issue=3|pages=839–864|doi=10.2466/pr0.1973.33.3.839|s2cid=144839425|issn=0033-2941|url-access=subscription}}</ref>

=== Moral ===
{{Main|Moral intelligence}}
Moral intelligence is the capacity to understand right from wrong and to behave based on the value that is believed to be right.<ref name="Langkah">'''[http://www.micheleborba.com/Pages/7virtues.htm The Step-By-Step Plan to Building Moral Intelligence]'''[http://www.micheleborba.com/Pages/7virtues.htm .] Retrieved 28 April 2016.</ref> It is considered a distinct form of intelligence, independent to both emotional and cognitive intelligence.<ref>Beheshtifar, M., Esmaeli, Z., & Moghadam, M. N. (2011). Effect of moral intelligence on leadership. European Journal of Economics, Finance and Administrative Sciences, 43, 6-11.</ref>

=== Book smart and street smart ===
Concepts of "book smarts" and "street smart" are contrasting views based on the premise that some people have knowledge gained through academic study, but may lack the experience to sensibly apply that knowledge, while others have knowledge gained through practical experience, but may lack accurate information usually gained through study by which to effectively apply that knowledge. [[Artificial intelligence]] researcher [[Hector Levesque]] has noted that:

{{blockquote|Given the importance of learning through text in our own personal lives and in our culture, it is perhaps surprising how utterly dismissive we tend to be of it. It is sometimes derided as being merely "book knowledge", and having it is being "book smart". In contrast, knowledge acquired through direct experience and apprenticeship is called "street knowledge", and having it is being "street smart".<ref>[[Hector J. Levesque]], ''Common Sense, the Turing Test, and the Quest for Real AI'' (2017), p. 80.</ref>}}

== Nonhuman animal ==
{{Main|Animal cognition}}
[[File:Macaca fascicularis aurea using a stone tool - journal.pone.0072872.g002f.png|thumb|left|A [[crab-eating macaque]] using a stone]]

Although humans have been the primary focus of intelligence researchers, scientists have also attempted to investigate animal intelligence, or more broadly, animal cognition. These researchers are interested in studying both mental ability in a particular [[species]], and comparing abilities between species. They study various measures of problem solving, as well as numerical and verbal reasoning abilities. Some challenges include defining intelligence so it has the same meaning across species, and [[operational definition|operationalizing]] a measure that accurately compares mental ability across species and contexts.<ref>{{cite book | chapter-url=https://www.cambridge.org/core/books/abs/cambridge-handbook-of-intelligence/animal-intelligence/82F839242F36A27D8B31D6AC0FE8B92F | doi=10.1017/9781108770422.018 | chapter=Animal Intelligence | title=The Cambridge Handbook of Intelligence | date=2019 | last1=Zentall | first1=Thomas R. | pages=397–427 | isbn=978-1-108-75581-8 }}</ref>

[[Wolfgang Köhler]]'s research on the intelligence of apes is an example of research in this area, as is Stanley Coren's book, ''[[The Intelligence of Dogs]]''.<ref>{{Cite book |last=Coren |first=Stanley |title=The Intelligence of Dogs |publisher=Bantam Books |isbn=978-0-553-37452-0 |year=1995 |oclc=30700778 |url=https://archive.org/details/intelligenceofdo00core }}</ref> Non-human animals particularly noted and studied for their intelligence include [[Common chimpanzee|chimpanzee]]s, [[bonobo]]s (notably the language-using [[Kanzi]]) and other [[great ape]]s, [[dolphin]]s, [[elephant]]s and to some extent [[parrot]]s, [[Rat IQ|rats]] and [[raven]]s.<ref>{{cite web |last1=Childs |first1=Casper |title=Words With An Astronaut  |url=https://valentitheme.com/classic/words-an-astronaut/ |website=Valenti |date=27 May 2020 |publisher=Codetipi |access-date=14 March 2021}}</ref>

[[Cephalopod intelligence]] provides an important comparative study. [[Cephalopod]]s appear to exhibit characteristics of significant intelligence, yet their [[nervous system]]s differ radically from those of backboned animals. Vertebrates such as [[mammal]]s, [[bird]]s, [[reptile]]s and [[fish]] have shown a fairly high degree of intellect that varies according to each species. The same is true with [[arthropod]]s.<ref>{{cite journal |last1=Roth |first1=Gerhard |title=Convergent evolution of complex brains and high intelligence |journal=Philos Trans R Soc Lond B Biol Sci |date=19 December 2015 |volume=370 |issue=1684 |pages=20150049 |doi=10.1098/rstb.2015.0049 |pmid=26554042|pmc=4650126 |doi-access=free }}</ref>

=== ''g'' factor in non-humans ===
{{Main|1=g factor in non-humans|l1=''g'' factor in non-humans}}

Evidence of a general factor of intelligence has been observed in non-human animals. First described in [[humans]], the ''g'' factor has since been identified in a number of non-human species.<ref name="Reader">Reader, S. M., Hager, Y., & Laland, K. N. (2011). "The evolution of primate general and cultural intelligence". ''Philosophical Transactions of the Royal Society'' B: Biological Sciences, 366(1567), 1017–1027.</ref>

Cognitive ability and intelligence cannot be measured using the same, largely verbally dependent, scales developed for humans. Instead, intelligence is measured using a variety of interactive and observational tools focusing on [[innovation]], [[habit]] reversal, [[social learning theory|social learning]], and responses to [[novelty]]. Studies have shown that ''g'' is responsible for 47% of the individual variance in cognitive ability measures in [[primates]]<ref name="Reader" /> and between 55% and 60% of the variance in [[mus musculus|mice]] (Locurto, Locurto). These values are similar to the accepted variance in [[IQ]] explained by ''g'' in humans (40–50%).<ref>Kamphaus, R. W. (2005). ''Clinical assessment of child and adolescent intelligence''. Springer Science & Business Media.</ref>

== Plant ==
{{Main|Plant perception (physiology)#Plant cognition|Plant cognition}}

It has been argued that plants should also be classified as intelligent based on their ability to sense and model external and internal environments and adjust their [[morphology (biology)|morphology]], [[plant physiology|physiology]] and [[phenotypic plasticity|phenotype]] accordingly to ensure self-preservation and reproduction.<ref>{{Cite journal |last=Trewavas |first=Anthony |date = September 2005|title=Green plants as intelligent organisms |journal=Trends in Plant Science |pmid=16054860 |volume=10 |issue=9 |pages=413–419 |doi=10.1016/j.tplants.2005.07.005|bibcode=2005TPS....10..413T }}</ref><ref>{{Cite journal| page = 841| year = 2002| pmid = 11859344| doi = 10.1038/415841a| issue = 6874| volume = 415| title = Mindless mastery| journal = Nature| last1 = Trewavas | first1 = A.| bibcode = 2002Natur.415..841T| s2cid = 4350140| doi-access = free}}</ref>

A counter argument is that intelligence is commonly understood to involve the creation and use of persistent memories as opposed to computation that does not involve learning. If this is accepted as definitive of intelligence, then it includes the artificial intelligence of robots capable of "machine learning", but excludes those purely autonomic sense-reaction responses that can be observed in many plants. Plants are not limited to automated sensory-motor responses, however, they are capable of discriminating positive and negative experiences and of "learning" (registering memories) from their past experiences. They are also capable of communication, accurately computing their circumstances, using sophisticated [[cost–benefit analysis]] and taking tightly controlled actions to mitigate and control the diverse environmental stressors.<ref name=":2">{{Cite journal | last1 = Goh | first1 = C. H. | last2 = Nam | first2 = H. G. | last3 = Park | first3 = Y. S. | doi = 10.1046/j.1365-313X.2003.01872.x | title = Stress memory in plants: A negative regulation of stomatal response and transient induction of rd22 gene to light in abscisic acid-entrained Arabidopsis plants | journal = The Plant Journal | volume = 36 | issue = 2 | pages = 240–255 | year = 2003 | pmid =  14535888| doi-access = free }}</ref><ref name=":3">{{Cite journal | last1 = Volkov | first1 = A. G. | last2 = Carrell | first2 = H. | last3 = Baldwin | first3 = A. | last4 = Markin | first4 = V. S. | title = Electrical memory in Venus flytrap | doi = 10.1016/j.bioelechem.2009.03.005 | journal = Bioelectrochemistry | volume = 75 | issue = 2 | pages = 142–147 | year = 2009 | pmid =  19356999}}</ref><ref>{{Cite journal | last1 = Rensing | first1 = L. | last2 = Koch | first2 = M. | last3 = Becker | first3 = A. | doi = 10.1007/s00114-009-0591-0 | title = A comparative approach to the principal mechanisms of different memory systems | journal = Naturwissenschaften | volume = 96 | issue = 12 | pages = 1373–1384 | year = 2009 | pmid =  19680619|bibcode = 2009NW.....96.1373R | s2cid = 29195832 | doi-access = free }}</ref>

== Artificial ==
{{Main|Artificial intelligence}}
Scholars studying artificial intelligence have proposed definitions of intelligence that include the intelligence demonstrated by machines. Some of these definitions are meant to be general enough to encompass human and other animal intelligence as well. An [[intelligent agent]] can be defined as a system that perceives its environment and takes actions which maximize its chances of success.<ref name=Russell>{{Cite book |author1=Russell, Stuart J. |author2=Norvig, Peter |title=[[Artificial Intelligence: A Modern Approach]] |publisher=Prentice Hall |location= Englewood Cliffs, N.J. |year=2003 |isbn=978-0-13-790395-5 |oclc=51325314}}</ref> [[Andreas Kaplan|Kaplan]] and Haenlein define artificial intelligence as "a system's ability to correctly interpret external data, to learn from such data, and to use those learnings to achieve specific goals and tasks through flexible adaptation".<ref>{{cite web|title=Kaplan Andreas and Haelein Michael (2019) Siri, Siri, in my hand: Who's the fairest in the land? On the interpretations, illustrations, and implications of artificial intelligence, Business Horizons, 62(1)|url=http://www.sciencedirect.com}}</ref> [[Progress in artificial intelligence]] can be demonstrated in benchmarks ranging from games to practical tasks such as [[protein folding]].<ref>{{cite news |title=How did a company best known for playing games just crack one of science's toughest puzzles? |url=https://fortune.com/2020/11/30/deepmind-solved-protein-folding-alphafold/ |access-date=21 February 2021 |work=Fortune |date=2020 |language=en}}</ref> Existing AI lags humans in terms of general intelligence, which is sometimes defined as the "capacity to learn how to carry out a huge range of tasks".<ref>{{cite news |last1=Heath |first1=Nick |title=What is artificial general intelligence? |url=https://www.zdnet.com/article/what-is-artificial-general-intelligence/ |access-date=21 February 2021 |work=ZDNet |date=2018 |language=en}}</ref>

Mathematician [[Olle Häggström]] defines intelligence in terms of "optimization power", an agent's capacity for efficient cross-domain [[mathematical optimization|optimization]] of the world according to the agent's preferences, or more simply the ability to "steer the future into regions of possibility&nbsp;ranked high in a preference ordering". In this optimization framework, [[Deep Blue (chess computer)|Deep Blue]] has the power to "steer a chessboard's future into a subspace of possibility which it labels as 'winning', despite attempts by [[Garry Kasparov]] to steer the future elsewhere."<ref>{{cite book |last1=Häggström |first1=Olle |author1-link=Olle Häggström |title=Here be dragons: science, technology and the future of humanity |date=2016 |location=Oxford |publisher=Oxford University Press |isbn=978-0191035395 |pages=103, 104}}</ref> [[Marcus Hutter|Hutter]] and [[Shane Legg|Legg]], after surveying the literature, define intelligence as "an agent's ability to achieve goals in a wide range of environments".<ref>{{cite news |author1=Gary Lea |title=The Struggle To Define What Artificial Intelligence Actually Means |url=https://www.popsci.com/why-we-need-legal-definition-artificial-intelligence/ |access-date=21 February 2021 |work=Popular Science |date=2015 |language=en}}</ref><ref>{{cite journal |last1=Legg |first1=Shane |last2=Hutter |first2=Marcus |title=Universal Intelligence: A Definition of Machine Intelligence |journal=Minds and Machines |date=30 November 2007 |volume=17 |issue=4 |pages=391–444 |doi=10.1007/s11023-007-9079-x|arxiv=0712.3329 |s2cid=847021 }}</ref> While cognitive ability is sometimes measured as a one-dimensional parameter, it could also be represented as a "[[hypersurface]] in a multidimensional space" to compare systems that are good at different intellectual tasks.<ref>{{cite book |last1=Bostrom |first1=Nick |title=[[Superintelligence: Paths, Dangers, Strategies]] |date=2014 |location=Oxford |isbn=978-0-19-967811-2  |at="Chapter 4: The Kinetics of an Intelligence Explosion", footnote 9 |publisher=Oxford University Press}}</ref> Some skeptics believe that there is no meaningful way to define intelligence, aside from "just pointing to ourselves".<ref>{{cite web |title=Superintelligence: The Idea That Eats Smart People |url=https://idlewords.com/talks/superintelligence.htm |website=idlewords.com |access-date=21 February 2021}}</ref>

== See also ==
{{Portal|Philosophy|Psychology}}
{{Columns-list|colwidth=20em|
* [[Active intellect]]
* [[Cattell–Horn–Carroll theory]]
* [[Extraterrestrial intelligence]], also referred to as Non-Human Intelligence
* [[Intellect]]
* [[Intelligence (journal)|''Intelligence'' (journal)]]
* [[Knowledge]]
* [[Neuroscience and intelligence]]
* [[Outline of human intelligence]]
* [[Passive intellect]]
* [[Superintelligence]]
* [[Sapience]]
}}

== References ==
{{Reflist|30em}}

== Further reading ==
* [[James Gleick|Gleick, James]], "The Fate of Free Will" (review of [[Kevin J. Mitchell]], ''Free Agents: How Evolution Gave Us Free Will'', Princeton University Press, 2023, 333 pp.), ''[[The New York Review of Books]]'', vol. LXXI, no. 1 (18 January 2024), pp. 27–28, 30. "[[Agency (philosophy)|Agency]] is what distinguishes us from machines. For biological creatures, [[reason]] and [[motivation|purpose]] come from acting in the world and experiencing the consequences. Artificial intelligences – disembodied, strangers to blood, sweat, and tears – have no occasion for that." (p. 30.) 
* [[Kenna Hughes-Castleberry|Hughes-Castleberry, Kenna]], "A Murder Mystery Puzzle: The literary puzzle ''[[Cain's Jawbone]]'', which has stumped humans for decades, reveals the limitations of natural-language-processing algorithms", ''[[Scientific American]]'', vol. 329, no. 4 (November 2023), pp.&nbsp;81–82. "This murder mystery competition has revealed that although NLP ([[natural-language processing]]) models are capable of incredible feats, their abilities are very much limited by the amount of [[context (linguistics)|context]] they receive. This [...] could cause [difficulties] for researchers who hope to use them to do things such as analyze [[ancient language]]s. In some cases, there are few historical records on long-gone [[civilization]]s to serve as [[training data]] for such a purpose." (p.&nbsp;82.)
* [[Daniel Immerwahr|Immerwahr, Daniel]], "Your Lying Eyes: People now use A.I. to generate fake videos indistinguishable from real ones. How much does it matter?", ''[[The New Yorker]]'', 20 November 2023, pp.&nbsp;54–59. "If by '[[deepfakes]]' we mean realistic videos produced using artificial intelligence that actually deceive people, then they barely exist. The fakes aren't deep, and the deeps aren't fake. [...] A.I.-generated videos are not, in general, operating in our media as counterfeited evidence. Their role better resembles that of [[cartoon]]s, especially smutty ones." (p.&nbsp;59.)
* [[Eyal Press|Press, Eyal]], "In Front of Their Faces: Does facial-recognition technology lead police to ignore contradictory evidence?", ''[[The New Yorker]]'', 20 November 2023, pp.&nbsp;20–26.
* [[Eka Roivainen|Roivainen, Eka]], "AI's IQ: [[ChatGPT]] aced a [standard intelligence] test but showed that intelligence cannot be measured by [[IQ]] alone", ''[[Scientific American]]'', vol. 329, no. 1 (July/August 2023), p.&nbsp;7. "Despite its high IQ, [[ChatGPT]] fails at tasks that require real humanlike reasoning or an understanding of the physical and social world.... ChatGPT seemed unable to reason logically and tried to rely on its vast database of... facts derived from online texts."
* [[Kenneth Cukier|Cukier, Kenneth]], "Ready for Robots? How to Think about the Future of AI", ''[[Foreign Affairs]]'', vol. 98, no. 4 (July/August 2019), pp.&nbsp;192–98. [[George Dyson (science historian)|George Dyson]], historian of computing, writes (in what might be called "Dyson's Law") that "Any system simple enough to be understandable will not be complicated enough to behave intelligently, while any system complicated enough to behave intelligently will be too complicated to understand." (p.&nbsp;197.) Computer scientist [[Alex Pentland]] writes: "Current [[machine learning|AI machine-learning]] [[algorithm]]s are, at their core, dead simple stupid. They work, but they work by brute force." (p.&nbsp;198.)
* [[Pedro Domingos|Domingos, Pedro]], "Our Digital Doubles: AI will serve our species, not control it", ''[[Scientific American]]'', vol. 319, no. 3 (September 2018), pp.&nbsp;88–93. "AIs are like [[autistic savant]]s and will remain so for the foreseeable future.... AIs lack [[common sense]] and can easily make errors that a human never would... They are also liable to take our instructions too literally, giving us precisely what we asked for instead of what we actually wanted." (p.&nbsp;93.)
* [[Gary Marcus|Marcus, Gary]], "Am I Human?: Researchers need new ways to distinguish artificial intelligence from the natural kind", ''[[Scientific American]]'', vol. 316, no. 3 (March 2017), pp.&nbsp;61–63. Marcus points out a so far insuperable stumbling block to artificial intelligence: an incapacity for reliable [[disambiguation]]. "[V]irtually every sentence [that people generate] is [[ambiguity|ambiguous]], often in multiple ways. Our brain is so good at comprehending [[language]] that we do not usually notice." A prominent example is the "pronoun disambiguation problem" ("PDP"): a machine has no way of determining to whom or what a [[pronoun]] in a sentence—such as "he", "she" or "it"—refers.
* {{cite book |title=The Cambridge Handbook of Intelligence |editor1-last=Sternberg |editor1-first=Robert J. |editor1-link=Robert Sternberg |editor2-last=Kaufman |editor2-first=Scott Barry |year=2011 |publisher=Cambridge University Press |location=Cambridge |isbn=978-0521739115 |doi=10.1017/9781108770422|s2cid=241027150 }}
* {{Cite book |title=IQ and Human Intelligence |last=Mackintosh |first=N. J. |author-link=Nicholas Mackintosh |year=2011 |edition=second |publisher=Oxford University Press |location=Oxford |isbn=978-0-19-958559-5}}
* {{Cite book |author=Flynn, James R. |title=What Is Intelligence: Beyond the Flynn Effect |edition=expanded paperback |location=Cambridge |publisher=[[Cambridge University Press]] |isbn=978-0-521-74147-7 |year=2009}}
** {{lay source |template=cite web |author=C Shalizi |date=27 April 2009 |title=What Is Intelligence? Beyond the Flynn Effect |type=Review |url=http://www.cscs.umich.edu/~crshalizi/reviews/flynn-beyond/ |archive-url=https://web.archive.org/web/20100614141825/http://www.cscs.umich.edu/~crshalizi/reviews/flynn-beyond/ |archive-date=2010-06-14 |website=University of Michigan}}
* {{cite book |title=What Intelligence Tests Miss: The Psychology of Rational Thought |last=Stanovich |first=Keith |year=2009 |publisher=Yale University Press |location=New Haven (CT) |isbn=978-0-300-12385-2 |url=https://archive.org/details/whatintelligence00stan }}
** {{lay source |template=cite web |author=Jamie Hale |title=What Intelligence Tests Miss |type=Review |website=Psych Central |url=http://psychcentral.com/lib/what-intelligence-tests-miss/0005083 |archive-url=https://web.archive.org/web/20131224083741/http://psychcentral.com/lib/what-intelligence-tests-miss/0005083 |archive-date=2013-12-24}}
* {{Cite book |author1=Blakeslee, Sandra |author2-link=Jeff Hawkins |author2=Hawkins, Jeff |title=On intelligence |publisher=Times Books |location=New York |year=2004 |isbn=978-0-8050-7456-7 |oclc=55510125 |url-access=registration |url=https://archive.org/details/onintelligence0000hawk }}
* {{cite book |title=The Nature of Intelligence |editor1-last=Bock |editor1-first=Gregory |editor2-last=Goode |editor2-first=Jamie |editor3-last=Webb |editor3-first=Kate |location=Chichester |publisher=Wiley |series=Novartis Foundation Symposium 233 |year=2000 |volume=233 |isbn=978-0471494348 |doi=10.1002/0470870850}}
** {{lay source |template=cite web |author=William D. Casebeer |date=November 30, 2001 |title=The Nature of Intelligence |type=Review |website=Mental Help |url=http://www.mentalhelp.net/poc/view_doc.php?id=851&type=book&cn=21 |archive-url=https://web.archive.org/web/20130526234853/http://www.mentalhelp.net/poc/view_doc.php?id=851&type=book&cn=21 |archive-date=2013-05-26}}
* {{cite book |title=Handbook of Intelligence |editor-last=Wolman |editor-first=Benjamin B. |others=consulting editors: Douglas K. Detterman, Alan S. Kaufman, Joseph D. Matarazzo |year=1985 |publisher=Wiley |location=New York |isbn=978-0-471-89738-5 |url=https://archive.org/details/handbookofintell0000wolm }}
* {{cite book |title=Measuring intelligence: A guide to the administration of the new revised Stanford-Binet tests of intelligence |last1=Terman |first1=Lewis Madison |last2=Merrill |first2=Maude A. |author-link1=Lewis Terman |year=1937 |publisher=Houghton Mifflin |location=Boston (MA) |series=Riverside textbooks in education |oclc=964301 }}
* {{cite book |last1=Binet |first1=Alfred |last2=Simon |first2=Th. |author-link1=Alfred Binet |title=The development of intelligence in children: The Binet-Simon Scale |others=E. S. Kite (Trans.) |location=Baltimore |publisher=Williams & Wilkins |year=1916 |series=Publications of the Training School at Vineland New Jersey Department of Research No. 11 |url=https://archive.org/details/developmentofint00binerich |page=[https://archive.org/details/developmentofint00binerich/page/n206 1] |access-date=18 July 2010 }}

== External links ==
{{Commons category}}
{{Wiktionary}}
{{Wikiquote}}
* {{In Our Time|Intelligence|p00545l3|Intelligence}}
* [http://www.indiana.edu/%7Eintell/map.shtml History of Influences in the Development of Intelligence Theory and Testing]. {{Webarchive|url=https://web.archive.org/web/20071111042550/http://www.indiana.edu/%7Eintell/map.shtml |date=11 November 2007 }}. Developed by [[Jonathan A. Plucker|Jonathan Plucker]] at [[Indiana University]].
* [http://www.scientificamerican.com/article.cfm?id=the-limits-of-intelligence The Limits of Intelligence: The laws of physics may well prevent the human brain from evolving into an ever more powerful thinking machine]. By Douglas Fox in ''[[Scientific American]]'', 14 June 2011.
* [https://arxiv.org/abs/0706.3639 A Collection of Definitions of Intelligence]

{{Human intelligence}}
{{Philosophy of mind}}
{{Authority control}}

[[Category:Intelligence| ]]
[[Category:Developmental psychology]]
[[Category:Psychological testing]]
[[Category:Differential psychology]]