20160320 Article Summary

<Affordances, Conventions, and Design> by Norman, D.A.

In the article, Norman re-introduces the concept of affordance to his readers in an apologetic manner. He does so because he thinks he has miscommunicated this concept in his previous writing. What he has defined as affordance in his earlier work should have been defined as perceptual affordance. Now, what is the different between "real" and "perceptual" affordance? This is better understood with examples. One example Norman gives is the following. When you put a graphical element on the computer screen, you have not created affordance there. Rather, it is more like a feedback or a perceived affordance that you created. Yes, users may click that graphical element, but that did not afford them to "click." Even without that element, users can click on the screen. The only thing it has made happen is that it added another object to be clicked. That is what perceived affordance does. It directs the affordance. So you can say that perceived affordance "advertises" affordance. 

Then what exactly is affordance? It seems like Norman has accepted its original definition that Gibson came up with. "Affordances are relationships. They exist naturally: they do not have to be visible, known, or desirable." Based on this definition, anything that brings about actions from the actors (that is, either a human or an animal) can be understood as affordance. Now, what should the designers be concerned about affordance when it comes to design then? The designers should focus on using affordance (both perceived and real) to elicit users to think that their actions are "meaningful and useful."

<Human Factors in Computing Systems> by Gaver, W.

Gaver provides wide ranging information about various types of affordances, broadening readers' perspectives. Acknowledging such elements as culture, experience and learning as ones to consider together with affordances, Gaver states that these are information that help users have better grasp of affordances. Such affordances include perceived, sequential, nested, tactile, auditory and so on. And when it comes to affordances, Gaver adds, it's not about one definition of affordance. But it's a combination or the interacted form of affordance that have influence on users. And knowing how to attribute each to the design makes the design "transparent" (that is, better in usability).
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