Essays & Articles


Interaction Design for Automobile Interiors

Donald A. Norman

Each new industry seems intent on repeating all the mistakes of previous industries. Now that computer software design understands design principles, now that website design is starting to understand them, it is time for new industries to fail.

The automobile industry is copying all the worst features of the computer industry, ignoring all the advances in user-interface design, and all the lessons about safety. Unlike home computers where bad design is simply a nuisance, with automobiles, bad design can be a major safety issue.

Try hitting the button for Station 6, while driving at high speeds in this sports car.

Consider the automobile radio. The photo shows the factory-installed radio for a 1996 Porsche. I’m certain the radio works fine, on a test bench. But the way it is usually installed in the automobile, it can be dangerous to change the station. Ten push buttons for stations, all in a row, each looking just like the adjacent ones. Imagine trying to select station 6 while driving at high speed. Worse, to change tone or speaker balance or to fast forward or reverse a tape or CD requires pushing one of the circular buttons above the radio display and then, within 10 seconds, depressing the proper lower button. And how do you know which lower button to push, why by the small lcd display, above the buttons. But not only are the labels small, at low contrast, but they suffer from parallax, so that they do not appear to be directly over the buttons they are marking. So it is impossible to use these controls without leaning over, which is a sure way to die.

The tiny print that must be read to adjust bass and treble, or “F” (whatever that does), with parallax error — all while driving at high speeds.

These are lessons long-ago learned in other industries. Why must the same mistakes be repeated here? The automobile is getting more and more complex: automatic braking, “following” modes for cruise control. Automatic braking to correct for skids, or if too close to nearby objects. And, of course the trend toward making the automobile interior like a home family room, complete with multiple displays, television, and high-quality audio system. Cellphones are already a distraction, but when coupled with automatic email readers, navigation systems, and other fancy accoutrements, the major resource of the driver — attention — is badly strained.

Consider the new BMW Series 7 automobile. The automobile key is a personal identifier that instructs the car to adjust the seat, mirrors, steering column, etc. to the key owner’s preferences. To start the engine, push the “Start” button. To turn the engine off? Push the same “Start” button. (Yes, it runs windows CE.)

“The iDrive plus display,” says the sales brochure, is a “user-friendly interface (that) offers quick access to over 700 settings, plus navigations system maps, phone book listings, and more” One control, one display — 700 settings? What were they thinking?

The New 7 series BMW no longer has all those knobs and buttons that clutter up the dashboard – you know, where each knob does one thing that you can count on. Instead, it has a single controller located on the center console that “functions similarly to a computer mouse.” It drives a display in the center of the dashboard. It is called the iDrive: i for “intuitive“)

The iDrive system is well-intentioned. It is indeed true that the number of displays and controls on the modern automobile dashboard have grown over the years. But the solution is better design, not hiding them away in a complex menu structure. Moreover, the designers didn’t try to minimize the controls, which would be the sensible thing to do. No, they took advantage of the power of the computer menu structure to amplify the number of options and things controlled, hence the “over 700 settings.” Bad idea. And then, they call it both “user friendly” and “intuitive.”

I have learned a number of cautions in the design business — red flags, they are called — terms that claim to evidence sensitivity to human needs but, in fact, reflect a complete lack of understanding of people. So here are terms to beware of: “fool-proof” or “idiot-proof” (oh, you mean you think your customers are fools or idiots?); “user-friendly” (which usually means to hold users by the hand and force them to do things one step at a time, in prescribed order, whether they like it or not); and “intuitive” (which in actuality means “so automatic it is not conscious,” but those who use the term forget that almost everything we call intuitive, such as walking or using a pencil took years of practice. Is that what we want to design — things that take years of practice? True, this describes the iDrive perfectly — years and years.)

I work in the field of usability and safely. I am appalled.

Do I think the iDrive is bad design, at least form a human standpoint? Yup. But don’t just take my word for it, look at some of the reviews. As USA Today put it: “it manages to complicate simple functions beyond belief." Auto review said “iDrive is not simple, no matter how clean it looks to the naked eye. … Our advice … Is to … retain basic manual controls for functions that are used every day.")

I do, however, have to keep an open mind. After all, I have not tested it. I did sit in the front seat in a showroom, but with everything turned off. I should drive it down the highway — or better, a crowded city street – and test the iDrive. Set a new radio station, check the directions to my destination, see how much fuel I have left, adjust the temperature of the interior — things I might actually do while driving. Only then can I pass judgment. Until then, I’m simply delighted that I am not planning to buy one. Alas, BMW promises that the features will migrate downward to all their autos. Will other auto makers follow?

Driving an automobile is a most misleading activity. Why, its intuitive, to use the correct meaning of the term. That is, after a training course, after those first frightening experiences where driving at 30 mph (50 Kph), seemed horrifyingly fast, then in just a few years of driving, it becomes automatic. You don’t have to think. Driving follows the classic laws of the development of expertise. At first, the concentration is on how the hands are held, especially in turning sharp corners, in trying to synchronize brake, clutch, shifting, turn signals, accelerator pedals, and looking in front, to the side, and behind, all seemingly simultaneously. With more experience, the emphasis shifts from concentration upon the hands and legs to learning how to steer and navigate. But eventually, with sufficient practice over months or years, the driving becomes effortless: one doesn’t steer the car or even turn it: one drives “to the store.”

But along with this expertise and ability to drive with little conscious awareness, comes a misleading impression. Most of the time, for a skilled driver, driving is indeed easy. Full attention does not have to be paid to the task. Thus, the skilled driver can look at the passenger or even turn around to look at the back seat. The driver can talk on the cellphone, listen to the radio, consult written instructions, and talk engagingly with the front seat passenger, looking them in the eye as they converse, all without apparent danger, even while driving at high speeds.

Skilled drivers can do other things because most driving is a low-bandwidth activity. Neither the road nor the other cars change rapidly. It is even possible to close ones eyes briefly without danger (I do not recommend that you try this). The problem, however, is that a dangerous situation can appear unexpectedly, and then full attention is required, as well as rapid response: sometimes even a tenth of a second can make a difference. (LED brake lights are safer than traditional lights because they light about 3/10th of a second faster, cutting driver reaction time: in that time the car at highway speeds has traveled around 30 feet – the difference between life and death when breaking to avoid collision).

The challenge presented by with automobile driving is that attentional demands are so uneven: mostly very light and then, oftentimes with little warning, extremely heavy, requiring responses measured in fractions of a second. Because it is not easy to predict when the attention will be required, the only safe way to drive is always to be undistracted, with complete attention to the task.


(This section is modified from Emotional Design, Chapter 5: People, places and things (Norman, 2004).)

Hurrah for the communication technologies that allow us continuous contact with our colleagues, friends, and families, no matter where we are, no matter what we are doing! But, however powerful text and voice messages, phone calls, and emails are as tools for maintaining relationships or supervising work, note that one person’s “keeping in touch” is another person’s interruption. The emotional impact reflects this discrepancy: positive to the person keeping in touch, but negative and disturbing to the person being subjected to interruption

Human, conscious attention is a component of the reflective level of the mind. It has limited capability. On the one hand, it limits the focus of consciousness, primarily to a single task. On the other hand, attention is readily distracted by changes in the environment. The result of this natural distractibility is a short attention span: new events continually engage attention. It is customary to argue that short attention spans are caused by whatever technology most upsets the generation doing the complaining –advertisements on radio or television, video games, music videos, and so on. But, in fact, the ready distractibility of attention is a biological necessity, developed through millions of years of evolution as a protective mechanism against unexpected danger: this is the primary function of the visceral level. This is probably why one byproduct of the negative affect and anxiety that results from perceived danger is a narrowing and focusing of attention: In danger, attention must not become distracted. But in the absence of anxiety, people are easily distracted, continually shifting attention. William James, the famous philosopher/psychologist, once said that his attention span was approximately ten seconds, and this in the late 1800s, far before the advent of modern distractions.

We carve out our own private spaces where needed. At home in our private study or bedroom, door locked if need be. At the office, in private room or, struggling to accomplish privacy, in cubicles or shared space. In the library, helped by the “shh, no talking” rules and convention, or by private carrels for the privileged few. In streets, where people will gather to form clusters of conversations, seemingly oblivious to those around them, if only temporarily.

But the real irritations of modern communication are those of human attention.

The limits on conscious attention are severe. When you are on a telephone call, you are doing a very special sort of activity, for you are a part of two different spaces, one where you are located physically, the other a mental space, the private location within your mind where you interact with the person on the other end of the conversation. This mental partitioning of space is a very special facility and it makes the telephone conversation, unlike other joint activities, demanding a special kind of mental concentration. The result is that you are partially away from the real, physical space, even as you inhabit it. This division into multiple spaces has important consequences for the human ability to function.

Do you talk on the telephone while driving an automobile? If so, you are dividing your conscious attention in a dangerous fashion, reducing your capacity to plan and anticipate. Yes, your visceral and behavioral levels of processing still function well, but not the reflective, the home of planning and anticipating. So driving is still possible, but primarily through the automatic, subconscious visceral and behavioral mechanisms. The part of driving that suffers is the reflective oversight, the planning, the ability to anticipate the actions of other drivers and any special conditions of the environment. That you can still appear to drive normally blinds you to the fact that the driving is less skillful, less able to cope with unexpected situations. Thus, the driving becomes dangerous, the cause being that distracting mental space. The danger does not stem from any requirement to hold the cellphone to your ear with one hand while steering with the other: a hands-free cellphone, where speaker and microphone are fixed to the car so that no hands are required, does not eliminate the distracting mental space. This is a new area of research, but the early studies seem to show that hands-free phones are just as dangerous as hand-held ones. The decrease in driver performance results from the conversation, not the telephone instrument.

Drive a car and hold a conversation with the passengers and, yes, some of the same distraction is present, especially because our social nature means that we tend to look at the person with whom we are conversing. Once again, the safety research is still at an early stage, but I predict that a conversation with real passengers will prove to be not as dangerous as one with far-away people, for the mental space we create for real passengers includes the auto and its surround, whereas the other one distances us from the auto. After all, we evolved to interact with others in the midst of other activities, but the evolutionary process could not anticipate communication at a distance.

We cannot take part in two intense conversations at the same time, at least not without degrading the quality and speed of each. Of course, we can and do take part in multiple text messaging conversations “simultaneously,” but the quote marks around “simultaneously” reflect that we don’t really do the operations at the same instant, but rather interweave the two. Conscious, reflective attention is only necessary for reading and for formulation of new messages, but once formulated, the automatic behavioral level mechanisms can guide the actual keystrokes while reflection switches over to the other conversation.

Because most activities do not require continual, full-time conscious attention, we are able to go about our daily activities continually dividing attention among multiple diversions. The virtue of this division of attention is that we keep in touch with the environment: we are continually aware of the things around us. Walk down the street chatting with a friend and you still have considerable resources left for a multitude of activities: to notice the new stores that have opened on the block; to glance at the newspaper headlines; even to eavesdrop upon neighboring conversations. The difficulties arise only when we are forced to engage in mechanical activities, such as driving an automobile, where the technological demands can require immediate response. Here is where the apparent ease with which we can often do these tasks misleads us into thinking that full attention is never required. Distractions and divided attention are among the powers of human processing. Far from being a liability, it is essential to social interaction. Our ability to time-share, to do multiple activities, enhances our social interactions. We are aware of others around us. We keep in touch with a large number of people The continual switching of attention is normally a virtue, especially in the world of social interaction. In the mechanical world, it can be a peril.

By continually being in communication with friends across a lifetime, across the world, we risk the paradox of enhancing shallow interactions at the expense of deep ones. Yes, we can hold continual, short interactions with numerous people, thus keeping friendships alive. But the more we hold short, brief, fleeting interactions and allow ourselves to interrupt ongoing conversations and interactions, the less we allow any depth of interaction, any depth to a relationship. “Continuously divided attention” is the way Linda Stone has described this phenomenon, but no matter how we may deplore it, it has become a commonplace aspect of everyday life.

Of course, this essay is incomplete without some positive recommendations — design specifications for the appropriate way to design, given the attentional demands and safety considerations for the driver. Ah yes, but this will have to wait. Work in progress.


The Attention span of ten seconds. I believe is in James’ “Principles of Psychology,” (James, 1890) but although I have relied on this quotation for more than 30 years, it is also more than 30 years since I read it. Try as I might, I have been unable to find it again in order to provide a proper bibliographic reference.

See William Whyte’s book City: Rediscovering the Center. (Whyte, 1988) for the importance of “place.”

Linda Stone, when she uttered that phrase (continuously divided attention) was then a Vice President of Microsoft. Personal communication, at the PopTech! Conference, Camden, ME, 2002

James, W. (1890). Principles of psychology. New York: Holt.

Norman, D. A. (2004). Emotional Design: Why We Love or Hate Everyday Things. New York: Basic Books.

Whyte, W. H. (1988). City: rediscovering the center. New York: Doubleday.