Affordance

“Afford” redirects here. For the surname, seeAfford (sur-name).An affordance is often taken as a relation between

The handles on a tea set provide an obvious affordance for hold-ing for individuals with hands.

an object, or an environment, and an organism that af-fords the opportunity for that organism to perform anaction.[1][2] For example, a knob affords twisting, andperhaps pushing, while a cord affords pulling. As a re-lation, an affordance exhibits the possibility of some ac-tion, and is not a property of either an organism or itsenvironment alone.[3][4]

Different definitions of the term have developed. Theoriginal definition described all actions that are physicallypossible. This was later adapted to describe action pos-sibilities of which an actor is aware. Some define affor-dance as a potential resource for some (not a particular)organism or species of organism, and so while inviting thepossible engagement of some species, not identified withany particular one.[5][6] The term has further evolved foruse in the context of human–computer interaction (HCI)to indicate the easy discoverability of possible actions.The word is used in a variety of fields: perceptualpsychology, cognitive psychology, environmental psy-chology, industrial design, human–computer interaction,interaction design, instructional design, science, technol-ogy and society (STS), and artificial intelligence.

1 As action possibilities

Psychologist James J. Gibson originally introduced theterm in his 1977 article “The Theory of Affordances”[7]and explored it more fully in his book The Ecological Ap-proach to Visual Perception[8] in 1979. He defined af-

fordances as all “action possibilities” latent in the envi-ronment, objectively measurable and independent of theindividual’s ability to recognize them, but always in re-lation to agents and therefore dependent on their capa-bilities. For instance, a set of steps which rises four feethigh does not afford the act of climbing if the actor isa crawling infant. Gibson’s is the prevalent definition incognitive psychology.Affordances were further studied by Eleanor J. Gibson,wife of James Gibson, who created her theory of percep-tual learning around this concept. Eleanor Gibson’s book,An Ecological Approach to Perceptual Learning and De-velopment explores affordances further.Jakob von Uexküll had already discussed the concept inthe early twentieth century,[9] calling it the “functionaltinting” (funktionale Tönung) of organisms with respectto stimuli.[10]

Anderson, Yamagishi and Karavia (2002) sought to de-termine whether visual attention or affordance forms thebasis of the motor signals generated by many everydaygraspable objects. By examining how the properties ofan object affect an observer’s reaction time for judg-ing its orientation, they provided evidence to indicatethat directed visual attention (not affordance) is respon-sible for the automatic generation of many motor signalsassociated with the spatial characteristics of perceivedobjects.[11]

2 As perceived action possibilities

In 1988, Donald Norman appropriated the term affor-dances in the context of human–machine interaction torefer to just those action possibilities that are readily per-ceivable by an actor. Through his book The Design ofEveryday Things,[12] this interpretation was popularizedwithin the fields of HCI and interaction design. It makesthe concept dependent not only on the physical capabil-ities of an actor, but also the actor’s goals, plans, values,beliefs, and past experiences. If an actor steps into aroom with an armchair and a softball, Gibson’s originaldefinition of affordances allows that the actor may throwthe chair and sit on the ball, because this is objectivelypossible. Norman’s definition of (perceived) affordancescaptures the likelihood that the actor will sit on the arm-chair and throw the softball. Effectively, Norman’s affor-dances “suggest” how an object may be interacted with.For example, the size and shape of a softball obviously

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2 5 REFERENCES

fit nicely in the average human hand, and its density andtexture make it perfect for throwing. The user may alsobring past experiences to bear with similar objects (base-balls, perhaps) when evaluating a new affordance.Norman’s 1988 definition makes the concept of affor-dance relational rather than subjective or intrinsic. Thishe deemed an “ecological approach”, which is related tosystems-theoretic approaches in the natural and social sci-ences. The focus on perceived affordances is much morepertinent to practical design problems from a human-factors approach, whichmay explain its widespread adop-tion.Norman later explained that this restriction in meaningof the term had been unintended, and that he would re-place the term by “perceived affordance” in any futurerevision of the book.[13][14] However, the definition fromhis book has been widely adopted in HCI and interactiondesign, and both meanings are now commonly used inthese fields.The different interpretations of affordances, althoughclosely related, can be a source of confusion in writingand conversation if the intended meaning is not made ex-plicit and if the word is not used consistently. Even au-thoritative textbooks can be inconsistent in their use ofthe term.[15]

3 False affordances

William Gaver[16] divided affordances into three cate-gories: perceptible, hidden, and false.

• A false affordance is an apparent affordance thatdoes not have any real function, meaning that the ac-tor perceives nonexistent possibilities for action.[17]A good example of a false affordance is a placebobutton.[18]

• A hidden affordance indicates that there are possi-bilities for action, but these are not perceived by theactor. For example, it is not apparent from lookingat a shoe that it could be used to open a wine bottle.

• For an affordance to be perceptible, there is infor-mation available such that the actor perceives andcan then act upon the existing affordance.

This means that, when affordances are perceptible, theyoffer a direct link between perception and action, and,when affordances are hidden or false, they can lead tomistakes and misunderstandings.

4 See also

• Usability

• Action-specific perception

• Form follows function

5 References[1] Leo van Lier (2004). “Relations”. e-Study Guide for:

Handbook of Psychology, Volume 6: Developmental Psy-chology: Psychology, Human development. Springer. p.4. ISBN 978-1402079047. “a relationship between anorganism and the environment that signals an opportunityfor or inhibition of action” See also a list of various defi-nitions titled “What are affordances”, p. 91

[2] DonNorman (2013). TheDesign of Everyday Things (Re-vised and expanded ed.). Basic Books. p. 11. ISBN978-0465050659. “An affordance is a relationship be-tween the properties of an object and the capabilities ofthe agent that determine just how the object could possi-bly be used.”

[3] Juval Portugali (1996). “Inter-representation Networksand Cognitive Mappings”. In Juval Portugali, ed.The construction of cognitive maps. Springer. ISBN9780585334851.

[4] Ulric Neisser (1989). “Chapter 1; Introduction: the eco-logical and intellectual bases of categorization”. In UlricNeisser, ed. Concepts and Conceptual Development: Eco-logical and Intellectual Factors in Categorization. Cam-bridge University Press. p. 12. ISBN 9780521378758.

[5] Edward S. Reed (1996). Encountering the World : To-ward an Ecological Psychology. Oxford University Press.p. 40. ISBN 9780195360936. “What makes somethingan affordance is that it has the right properties to supportsome species’ behavioral processes”

[6] For an extended discussion of views on affordances, seeAnthony Chemero (2011). "§7.2 Affordances 1.0”. Rad-ical Embodied Cognitive Science. MIT Press. pp. 136 ff.ISBN 9780262258081.

[7] James J. Gibson (1977), The Theory of Affordances. InPerceiving, Acting, and Knowing, edited by Robert Shawand John Bransford, ISBN 0-470-99014-7.

[8] James J. Gibson (1979), The Ecological Approach to Vi-sual Perception, ISBN 0-89859-959-8.

[9] Uexküll, Jakob von (1980 [1920 etc.]), Kompositionsleh-re der Natur, edited by Thure von Uexküll, Frankfurt amMain.

[10] Dorion Sagan (2010). “Introduction: Umwelt afterUexküll”. In Jakob von Uexküll, Marina von Uexküll,Joseph D. O’Neil. A Foray Into the Worlds of AnimalsandHumans: With a Theory ofMeaning (JosephDO'Neiltranslation of 1940 ed.). University of Minnesota Press.p. 5. ISBN 9781452903798. “Organisms in their life-worlds recognize not only sensory inputs, but also func-tional tones, the use they need to make of certain stimuliif they are to do what they need to survive.”

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[11] Anderson, S. J.; Yamagishi, N.; Karavia, V. (2002). “At-tentional processes link perception and action”. Proceed-ings of the Royal Society B: Biological Sciences 269 (1497):1225. doi:10.1098/rspb.2002.1998.

[12] Donald Norman, The Design of Everyday Things, ISBN0-465-06710-7. Originally published under the title ThePsychology of Everyday Things, often abbreviated toPOET.

[13] Donald A. Norman (1999). Affordance, Conventions andDesign. Interactions 6(3):38-43, May 1999, ACM Press.

[14] Affordance, Conventions and Design (Part 2)

[15] In Human–Computer Interaction, Preece et al. (1994, p.6) explicitly define perceived affordances as being a subsetof all affordances, but the meanings are intermingled laterin the same paragraph by talking about “good affordance";in Universal Principles of Design, Lidwell, Holden & But-ler (2003, p. 20) first explain that round wheels are bettersuited for rolling than square ones and therefore better af-ford (i.e. allow) rolling, but later state that a door handle“affords” (i.e. suggests) pulling, but not pushing.

[16] Gaver, William W. (1991). “Technology affordances”.“Proceedings of the SIGCHI conference on Human fac-tors in computing systems Reaching through technology- CHI '91”. p. 79. doi:10.1145/108844.108856. ISBN0897913833.

[17] “Affordances”

[18] “Placebo buttons, false affordances and habit-forming”

6 Additional reading

• The role of affordances in evolution and niche con-struction is discussed by RobWithagen, Margot vanWermeskerken (2010). “The role of affordances inthe evolutionary process considered: A niche con-struction perspective”. Theory and Psychology 20(4): 489–510. doi:10.1177/0959354310361405.

• The role of affordances in agency is discussedby Rob Withagen, Harjo J de Poel, DuarteAraújo, Gert-Jam Pepping (2012). “Affordancescan invite behavior: Reconsidering the re-lationship between affordances and agency”.New Ideas in Psychology 30 (2): 250–258.doi:10.1016/j.newideapsych.2011.12.003.

• Affordance and computation is discussedby AJ Wells (2002). “Gibson’s affor-dances and Turing’s theory of computa-tion”. Ecological psychology 14 (3): 140–180.doi:10.1207/S15326969ECO1403_3.

7 External links• A series of slides concerning theories of vision and(incidentally) the role of affordances and some in-teresting optical illusions concerning affordancesAaron Sloman (March 12, 2014). “What’s visionfor, and how does it work? From Marr (and earlier)to Gibson and beyond”. Retrieved May 22, 2014.

4 8 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

8 Text and image sources, contributors, and licenses

8.1 Text• Affordance Source: http://en.wikipedia.org/wiki/Affordance?oldid=629640870 Contributors: The Anome, LionKimbro, Vaughan, Pnm,Murb:, Sbwoodside, Nickg, Greenrd, Jogloran, Wetman, Robbot, AlainV, AdamReed, ZimZalaBim, Ruakh, Enochlau, DocWatson42,Mzajac, Rculatta, MichaelMcGuffin, Naive cynic, Xezbeth, Pavel Vozenilek, Abroeck, Johnkarp, Gaal, Diego Moya, Aquelajames, KellyMartin, Psychologesetz, Jeff3000, Sjakkalle, Lockley, XP1, MZMcBride, Jeffmcneill, Penumbra2000, Aapo Laitinen, Imnotminkus,YurikBot, Welsh, SmackBot, Tekhnofiend, Harnad, Lambiam, Robofish, Ehheh, Ofol, CmdrObot, Cydebot, Mattisse, Thijs!bot, Magi-oladitis, Dekimasu, Steven Walling, Emw, Prufock, Mcuringa, LittleHow, Cameron.g.brown, Roconnell2580, PaulTanenbaum, Brockle,Forlornturtle, Larkuur, Wpmetropol, Jojalozzo, Alethe, Junling, Szalagloria, Yelsdrab, Nnemo, Brews ohare, Addbot, MrOllie, LaaknorBot,Lightbot, Yobot, AnomieBOT, Emreugur, Pinethicket, Morton Shumway, RjwilmsiBot, Stevenliuyi, Roberto the Benevolent, Chuispaston-Bot, Vitalii-Fedorenko, Jkwitt, Data2011, Emastroi, Jamesx12345, Daniel.glazman, , Boneraw, Srnejad, SathishDhanabalan, OMPIREand Anonymous: 46

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