What this country needs, muses David Kelley, may be a truly functional pizza cutter. Or perhaps it is a soda vending machine that eliminates the risk of back injury from stooping to extract a cold cola. More likely, it could be a redesigned hospital emergency room that takes the needs of patients into account.

Or it may be something no one has thought of yet. The point, says Kelley, who heads the Stanford Joint Program in Design, is that designers will not know the identity of the next truly innovative products — what Kelley calls the “new-to-the-world stuff” — until careful study of people’s behavior uncovers them.

Isn’t that more the realm of anthropology than engineering? Perhaps it was in the past, answers Kelley, but not anymore. In the future, the important products — things like the computer mouse, or the Palm V, or even the grip of the Oral-B kids toothbrush — will come from designers who understand not only the intersection between engineering and aesthetics, but between engineering, business, and social sciences such as psychology and anthropology.

Kelley, who holds the Donald W. Whittier Professorship in Mechanical Engineering, should know. He had a hand in developing each of the instantly recognizable products listed above, either through his own innovative work or through IDEO, the internationally known design firm he founded and chairs.

Today, says Kelley, product design is on the verge of another move forward in its evolution. When the Joint Program in Design got its start as a partnership between the Department of Mechanical Engineering and the Department of Art and Art History in 1958, he explains, it broke new ground by bringing concepts in creative thinking and aesthetics to engineers. The next step, he says, is to take the engineers to the people.

“In the past when we would try to design things for people, we’d take the technology to a company and say, ‘Let’s build a toaster that takes four slices instead of two,’” Kelley says. “Later, we’d try to convince people it was a good idea. We now believe that the way to design products is to go out and actually understand the people first, to have empathy for what they want. Maybe it isn’t a toaster at all.”

To do that, Kelley believes, engineers must work not only beside social scientists and businesspeople but among the people who will use their products.

“You actually have to drag the engineers out there in the field so they really do have empathy for the user,” Kelley says. “But the good news is afterward they get more excited than they were before. Now they’re not just designing something, they’re pleasing someone. They can picture that person crouching down to get the can of cola, or pressing down on the pizza cutter, or waiting in the lobby of the ER.”

If the idea of engineers studying human behavior is startling, the idea of product design as a partnership between disciplines is not entirely new. Kelley and faculty from the Graduate School of Business and the School of Humanities and Sciences have already taught several courses together. Courses taught by Matt Kahn, professor of art and art history, have long been an essential part of the program. Now, Kelley argues, it makes sense to consistently add social sciences, business, and other engineering disciplines to the design process.

As an example, Kelley points to the efforts of a group of Stanford graduate students in engineering and business who are working to bring safe, affordable lighting to people in India, China, and Mexico.The students came together last spring for a class taught by Kelley, Professor James Patell of the Graduate School of Business, and Consulting Assistant Professor Bill Behrman of the School of Engineering.There they learned that the light source for more than a billion people worldwide are lamps that burn fuel such as kerosene, a smoky, expensive, and potentially dangerous choice.

Within 10 weeks, the class developed prototypes of three lamps using light-emitting diodes, or LEDs, and tailored to the needs of people in each of the countries.The lamps, powered either by batteries recharged using attached solar panels, by the solar panels and supplemental chargers that draw power from electric grids, or by conventional batteries, provide enough light to read by at a fraction of the cost of kerosene lamps.

The students also wrote separate business plans for providing the lamps in each of the countries. And during the summer, five traveled to India to observe how people used the prototype lamp and to investigate potential manufacturers and distributors. If funding is found, next year the students will work with the nonprofit Light Up the World Foundation to launch the lamps abroad.

The class clearly illustrates why engineers, social scientists, and businesspeople need each other to create the next generation of bold and meaningful designs, says Kelley. Not one of the groups could have pulled it off alone.

“The whole point is we’re networked together now,” he says. “It’s not just you, it’s not just me. We’re all tied to a whole bunch of other people, and things work best when we can work together.”