Bret Vector's classic paper "Magic Ink: Information Software and the Graphical Interface" boldly states: "Interactivity considered harmful"!

When I first read that, I was flabbergasted and offended, because I love interactivity. But he's right.

"Interaction should be used judiciously and sparingly, only when the environment and history provide insufficient context to construct an acceptable graphic." -Bret Victor, Magic Ink

This is a critically important lesson to apply to automotive user interfaces. It's much safer if, as much as possible, instead of being interactive, the user interface predicts and infers from context and history what the user wants, when or before they want it, and presents it to them without them asking, so it's there when they need it.

http://worrydream.com/MagicInk/

Interactivity considered harmful

Chris Crawford defines interaction as a three-phase reciprocal process, isomorphic to a conversation: an interactant listens to her partner, thinks about what was said, and speaks a response. Her partner then does the same. See Crawford’s book The Art of Interactive Design (2003), or his essay Fundamentals of Interactivity (1993). For manipulation software, interaction is perfectly suitable: the user views a visual representation of the model, considers what to manipulate next, and performs a manipulation. The software, in turn, inputs the user’s manipulation request, updates the model, and displays the updated representation. With good feedback and an effective means of “speaking” to the software, this process can cycle smoothly and rapidly. It mimics the experience of working with a physical tool.

Information software, by contrast, mimics the experience of reading, not working. It is used for achieving an understanding—constructing a model within the mind. Thus, the user must listen to the software and think about what it says… but any manipulation happens mentally. Except possibly for signaling a decision, such as clicking a “buy” button, but that concludes, not constitutes, a session. The only reason to complete the full interaction cycle and speak is to explicitly provide some context that the software can’t otherwise infer—that is, to indicate a relevant subset of information. For information software, all interaction is essentially navigation around a data space.

For example, Amazon’s data space consists of their catalog of items. For a yellow pages directory, the data space contains all business listings; for a movie guide, all showtimes and movie information; for a flight planner, trips to and from all airports. In all of these cases, every interaction, every click and keystroke, search term and menu selection, simply serves to adjust the user’s view into the data space. This is simply navigation.

Alan Cooper defines excise in this context as a cognitive or physical penalty for using a tool—effort demanded by the tool that is not directly in pursuit of a goal. For example, filling a gas tank is done to support the car, not the goal of arriving at a destination. Cooper goes on to assert that software navigation is nothing but excise:

…the most important thing to realize about navigation is that, in almost all cases, it represents pure excise, or something close to it. Except in games where the goal is to navigate successfully through a maze of obstacles, navigation through software does not meet user goals, needs, or desires. Unnecessary or difficult navigation thus becomes a major frustration to users. In fact, it is the authors’ opinion that poorly designed navigation presents the number-one problem in the design of any software application or system… Alan Cooper and Robert Reimann, About Face (2003), p143.

If all interaction is navigation, and navigation is the number-one software problem, interactivity is looking pretty bad already. However, when compared with the other two sources of context, 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. See Donald Norman’s book The Design of Everyday Things (2002), p9. 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. 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!

Beyond these cognitive problems are physical disadvantages of interaction. The hand is much slower than the eye. Licklider described spending hours plotting graphs and seconds understanding them. A user who must manually request information is in a similar situation—given the mismatch between mousing and reading speeds, most of her time may be spent navigating, not learning. Further, the user might prefer to learn information while using her hands for other purposes, such as writing or eating or stroking a cat. Each time software demands the user’s hands, this activity must be interrupted. Finally, the growing prevalence of computer-related repetitive stress injuries suggests that indiscriminate interactivity may be considerably harmful in a literal, physical sense.

Unless it is enjoyable or educational in and of itself, interaction is an essentially negative aspect of information software. There is a net positive benefit if it significantly expands the range of questions the user can ask, or improves the ease of locating answers, but there may be other roads to that benefit. As suggested by the above redesigns of the train timetable, bookstore, and movie listings, many questions can be answered simply through clever, information-rich graphic design. Interaction should be used judiciously and sparingly, only when the environment and history provide insufficient context to construct an acceptable graphic.

It is unfortunate that the communities concerned with human factors of electronic artifacts have latched onto the term “interaction.” Most professional communities and academic programs use the term Human-Computer Interaction, or HCI; the ACM special-interest group is CHI, the converse. Many practitioners, following Cooper and Bill Moggridge, refer to their profession as “interaction design.” For information software, the real issue is context-sensitivity. Interaction is merely one means of achieving that. And as long as “speaking” is constrained to awkwardly pushing metaphors with a mouse, interaction should be the last resort.

The working designer might protest that interaction is unavoidable in practice, and may even consider my ideal of interaction-free software to be a scoff-worthy fantasy. This is only because the alternatives have been unrecognized and underdeveloped. I believe that with the invention of new context-sensitive graphical forms and research into obtaining and using environment and history, the clicking and dragging that characterizes modern information retrieval will be made to seem laughably archaic. But every condonation of “interactivity,” from the annals of academia to the corporate buzzvocabulary, postpones this future.