Interaction is a cost center in interface design

Interface designers are often interested in designing “engaging interactions,” but interactions are, by default, a burden imposed upon the user—a tax to be avoided. If I’m using an interface to analyze some data, the ideal is zero interactions: I read a screen of information, notice a pattern, and answer my question. Every filter box, navigation button, and scrubber is an extra cost.

Of course, sometimes there’s too much information to understand without interaction, no matter how thoughtfully presented. In these instances, careful use of interactivity can yield benefit by filtering the possibility space, but that benefit must always be carefully balanced against the excise it imposes.

Bret Victor additionally observes (2006):

Interactivity has even worse problems than simply being a frustrating waste of time:

The user has to already know what she wants in order to ask for it. Software that infers from history and the environment can proactively offer potentially relevant information that the user wouldn’t otherwise know to ask for. Purely interactive software forces the user to make the first move.

The user has to know how to ask. That is, she must learn to manipulate a machine. Donald Norman’s concept of determining a user’s “mental model” has become widespread in the software usability community, and is now considered a core design challenge. However, Norman described this concept in the context of mechanical devices. It only applies to software if the software actually contains hidden mechanisms that the user must model. A low-interaction, non-mechanical information graphic relieves both user and designer from struggling with mental models.

Navigation implies state. Software that can be navigated is software in which the user can get lost. The more navigation, the more corners to get stuck in. The more manipulable state, the more ways to wander into a “bad mode.” State is the primary reason people fear computers—stateful things can be broken. (Sidenote: The only state kept by a book is which page it is open to, which is why “getting lost in a book” describes a pleasurable experience!)


Victor, B. (2006, March 15). Magic Ink: Information Software and the Graphical Interface.