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IADIS International Conference WWW/Internet 2010According to Gibson (1979), an affordance is unique for one person or animal, which makes it differentfrom a simple physical measure that is an object property. Affordances are objective, real and physical in away that "the affordance of something does not change as the need of the observer changes"; we do not needto classify and label things in order to perceive what they afford.To O’Neill (2008), “Gibson is attempting to describe an affordance as an emergent property of theperceptual process consisting of the properties of the object itself and the perceptual capacities of theperceiver”. Different layouts afford different behaviors for different animals; a terrestrial surface, forexample, is climb-on-able, fall-off-able, get-underneath-able or bump-into-able relative to a specific animal.Gibson also defined the term social significance to describe what one person affords to other: “whatother persons afford comprises the whole realm of social significance for human beings. We pay the closestattention to the optical and acoustic information that specifies what the other person is, invites, threatens,and does." (Gibson, 1979).Many authors appropriated Gibson’s original term for their own uses with significant differences in theconceptualization. The next section briefly explains some different author’s perspectives on the concept.3.1 Affordances in DesignTable 1. Synthesis of the evolution of HCI field and the concept of affordance60-70’s 80’s 90’s 2000’s 2010’s ...HCI Paradigm 1 1 st 2 nd 3 rdTechnology 2,3,4 Mainframes Personal computers Network MobilityConstruction ofmeaning 1Predominantinfluence 1Main questionModels andTheories 1Concept ofaffordanceUsers wereprofessionalsNon-functionalrequirements (e.g.usability)Computer graphicsemergedPragmatic approach.Ignore it unless itcauses a problemEngineeringHuman FactorsHow to optimize user’sinteraction with themachine? 1,5Systematic methods of testingEcological approach,independent of cognition(Gibson, 1977)Applied todesign, part ofperception(Norman,1988)Meaning interpretation in termsof information flowsCognitive scienceHow users might interactwith each other? 2Situated action, Distributed Cognition,Activity Theory, Ethno methodology,Qualitative approach, Action TheoryCan be associatedwith perception(Gaver, 1991)1 (Harrison et al., 2007); 2 (Harper et al., 2008); 3 (Bødker, 2006); 4 (ITEA, 2009); 5 (Sellen, 2009);Social affordance,cultural context(Stamper, 2001)Ubiquitous computing,Web 2.0, VR, AR,Interaction based ongestures, sensors, 3DIt is the focus,constructed on the fly,collaboratively, differentcontexts. Machinesreplacing humansEmbodied interaction,Meaning makingHow to address humanvalues into research anddesign? 2Emotion, Aesthetics,Pragmatic/culturalfocus on experienceSocial signifier(Norman,2008)Motivational affordance(Zhang, 2008)When Norman first applied the concept of affordance in design, he stated that his conceptualization “refers tothe perceived and actual properties of the thing” (Norman, 1988). Those properties determine how the thingcould possibly be used. Taking advantage of it, no labels or instructions are needed. Norman (2004) proposeda distinction between real affordances, those related to the physical properties of the world – which is closeto Gibson’s definition – and perceived affordances which are subjective representations in the mind.To Norman, the computer system, with its keyboard, display screen, pointing device affords pointing,touching, looking, and clicking on every pixel of the display screen – that is the real or physical affordance.E.g.: Figure 1a: a portable computer by Sony® that suggests movement and to handling with both hands.All that the user interface designer has available in graphical, screen-based interfaces are related toperceived affordances (Neris & Baranauskas, 2010). Affordance is not the simple presence of an element onscreen, but a suggestion or a clue about how to use it. Figure 1b illustrates a perceived affordancehighlighting a donation button in a web interface. As Norman (2008) explains: “[…] To Gibson, affordancesdid not have to be perceivable or even knowable – they simply existed. When I introduced the term into185