As commonplace as discourse on “affordances” has become in design theory and media theory has become, I deeply sympathize with Donald Norman’s attempts at correcting their rampant misuse and providing greater specificity as to what is meant by an affordance or a constraint. I disagree with Norman, however, when he implies at the end of his article, that discourse on affordances and constraints might be better suited if left to “physical objects, real knobs, sliders, and buttons” (p. 42). In fact, given Janet Murray’s charge to consider all computational media as a single medium, I think the application of affordances to digital media demonstrates the philosophical richness of the concept in a way that retrieves and updates the foundational concepts of potentiality and actuality.
Potentiality has to do with the possibility of an occurrence, whereas actuality has to do with the reality of an occurrence. In terms of affordances, JJ Gibson’s original concept shared much more similarities with potentiality than actuality. A physical book, for example, could afford anything which its properties would feasibly allow, including expected features such as reading, dog-earing, page turning, but also including absurdities such as throwing, sitting-on, or even eating. For Gibson, affordances have to do with the limits of potentiality for an object — what can be done with it, not what is done with it.
Concerned with design, Norman talks about perceived affordances in terms of communicating the proper use of an object through design choices, and not about the total scope of potentiality of an object. In other words, Norman talks about holding the user’s hand in leading them through to actualized affordances as useful for the user in distinguishing the most productive use of an object as opposed to the total scope of its potential affordances. For example, e-readers, like the early Kindle designs encourage the actualization of a “turning the page” affordance by the design of buttons with arrows pointing in either direction. This design operates as a sort of communication to the user that the device contains this potential affordance, for which it is designed to be actualized. For Norman, inserting these buttons did not “create the affordance.” The affordance existed independently of the buttons as a function of the computational design of the Kindle. The buttons merely work as a tool for the user to actualize the potential affordance which was there all along.
For examples like the book, or even the Kindle in some respects, this delineation seems rather tedious. However, if we take literally Janet Murray’s claim that all computational media are one medium, it becomes immediately much more useful. Murray claims that all digital media is “created by exploiting the representational power of the computer” (p. 8). In other words, she is stating that all digital media are defined by the set of affordances associated with the capacity to interpret and represent electrical impulses in a way understandable to human users (this definition is overly broad because it doesn’t account for differences in input like keyboards or touchscreens, but it works for our purposes here). Therefore, all computational media possess the potential affordances to do any number of actions associated with this process: scroll through a webpage, click a link, etc. The role of the designer, particularly the designer of computational software, is to guide the user to actualizing the limited set of useful potential affordances available in a particular program. As Norman says, “The affordance exists independently of what is visible on the screen” (p. 40), it is the designers role to make it visible or obvious to the user so they might actualize it.
Murray, J. (2012). Inventing the Medium: Principles of Interaction Design as a Cultural Practice. Cambridge, MA: MIT Press.
Norman, D. (1999). “Affordance, Conventions, and Design.” Interactions 6, no. 3: 38-43.