A few years ago in a rural part of East Africa, one of our foundation's grantees was having an unexpected problem: its treadle pumps were selling very well in some places yet very poorly in others. Treadle pumps help farmers irrigate small plots of land and turn a subsistent yield into a surplus they can sell.

Our grantee started tracking who was and who was not buying the pump — and soon learned that sales were slow because of how the pumps operated. Farmers had to stand on the pump and pedal, a movement that required a lot of hip swaying, similar to riding a bicycle. That presented a problem in communities where cultural norms considered women's hips swaying to be inappropriate. As long as the pump operated that way, most women farmers simply weren't going to buy it, no matter how useful or profitable it could be. Once the grantee realized the problem, the pump was redesigned, and adoption rates shot up.

This example illustrates a trend that makes me very optimistic about the future: the use of human-centered design principles to help people lead better lives.

At the most basic level, human-centered design is about listening. Organizations like our grantee go into communities to learn about the challenges people face and the realities of their lives. It's a process grounded in the understanding that the most valuable tools for improving people's lives aren't necessarily the ones designed in the shiniest labs; they are the ones people can and will actually use.

While this seems like a common-sense approach, the conventional wisdom among product designers going back decades was that if you could design a product that was sufficiently attractive and ingenious, people would want it, buy it, and shape their behavior around it.

In the 1980s, that began to change. In part, that shift was driven by Donald Norman, a cognitive scientist at the University of California San Diego. Everywhere he looked, Norman saw products that frustrated people: doors that were difficult to open, staplers that didn't staple, shower controls that seemed to require days of careful study to decipher.

When we better understand the realities of these women's lives, we are able to design and deliver solutions that are more useful to them

Norman and his peers believed that people shouldn't have to adjust their behavior to products. Instead, it should work the other way around: products should be adjusted to fit people's behavior. They coined the term "user-centered design," a concept that, coincidentally, rose to prominence about the time of the computer revolution. When I worked in marketing and software development at Microsoft, I saw firsthand how the needs of the customer informed the development of our products.

Today, the development community is starting to apply this same philosophy. In Ghana, for instance, it has driven amazing sanitation improvements. Where communities used to share a public toilet, residents complained about the difficulty of accessing them in the middle of the night. Now companies have shifted to renting private toilets to individuals, to make them more accessible when they are most needed — and therefore, more likely to be used.

One of the most exciting aspects of this change is what it will mean for women and girls in developing countries. In many places, women and girls don't have a voice in society, so their needs are invisible and their preferences go ignored in their communities. As a result, the tools and solutions the global health community develops often don't reflect their needs or preferences, either.

Bill and I started our foundation because we believe every life has equal value, and we believe everyone should have a voice in the conversations that will shape their future. Human-centered design helps ensure that these important conversations include everyone.

To cite one example I've seen over and over again, health clinics in many African countries will claim they are well-stocked with contraceptives when, in fact, the only contraceptives they have available are condoms. That's a problem, because many women tell us their partners won't agree to use condoms. For that reason, women prefer injectable forms of birth control. These injectable birth control methods last longer and are invisible, making them an effective way for women to protect their health and help better space their pregnancies — which we know benefits both them and their children.

This is a perfect example of the impact of human-centered design's power. On paper, condoms and injectables appear almost equally effective. But when we better understand the realities of these women's lives, we are able to design and deliver solutions that are more useful to them.

Putting women's needs front and center is especially important because women play a critical role in catalyzing global health and development: they are, themselves, agents of progress. When women like the farmers in East Africa are able to earn additional income, they invest in their children. When women are in charge of a household budget, they prioritize health, education, and nutritious food for the entire family. That means healthier, better-educated children today — and healthier, more prosperous communities tomorrow.

The women I have met all over the world already have the potential to lift themselves out of poverty, to drive global development, and to improve global health. By helping women express their unique needs and preferences, human-centered design gives us all a means to unlock that potential.