ASSOCIATED PRESS (AP) -- Not paying by smartphone? You soon will.

Even though most consumers don't use their smartphones to pay for anything, some of the world's largest financial institutions and dozens of small tech start-ups are making big bets on the adoption of the so-called mobile wallet.

Many of them gathered Wednesday at Harvard University to hash out the future of buying and selling via smartphones and other Internet-connected gadgets during a two-day forum that includes MasterCard, PayPal, and the Boston mobile payments start-up Scvngr Inc. Even a former vice president showed up: Al Gore, whose new book, "The Future: Six Drivers of Global Change," deals with the worldwide impact of technological innovations.

Consumers have for years been able to use smartphone apps to pay for items in stores and restaurants. But only recently has the technology started catching on, and start-ups -- many of them in Boston -- as well as financial service giants, are racing to capture the emerging market.

"Every device will become a commerce device," said Gary Flood, president of global products and solutions for MasterCard, which is a sponsor of the summit, Innovation Project 2013. "Technology is opening up the potential to do things in a different way around the world."

So far, acceptance of mobile wallet technology is split along generational lines, Flood said, with many young people more willing to use their devices to pay for everything from a cup of coffee to a taxi ride. "They don't use cash," he said.

Indeed, people younger than 35 are more inclined to pay via smartphone, according to a December poll by Harris Interactive Inc., a New York consumer research firm. Though just 4 percent of respondents have used their phones to buy something, the survey found, more than 60 percent expect the devices will eventually replace cash and credit cards.

A growing number of Boston start-ups are moving to get in front of the trend.

In addition to Scvngr, which operates the payment network known as LevelUp, there are Paydiant Inc. of Wellesley, Roam Data Inc. in Boston, Leaf in Cambridge, and several other small firms.

''We didn't invent the mobile wallet, but we're inventing ways to make it work," said Will Graylin, a former Roam Data chief executive who is unveiling his latest start-up, ActPay, at the Harvard conference.

The Woburn company, which has grown to about two dozen employees, is attempting to create a single point-of-sale device that will allow merchants to accept any mobile payment application a consumer wants to use.

Different apps and devices are available from companies such as Square Inc., LevelUp, PayPal, Google Inc., and MasterCard. Many of the biggest retailers accept mobile payments, but they don't take every payment option that's out there.

''Until you solve that particular problem," Graylin said, "you can't really drive much consumer adoption."

PayPal, which recently opened an office in Boston's Financial District, is making a push to bring its service for paying over the Web to brick-and-mortar stores. It is now available in 18,000 stores nationwide.

"Cash is starting to get digitized," said Don Kingsborough, vice president of retail sales for PayPal.

Since the smartphone has become ubiquitous, consumers want to use it for shopping and buying whether they're at home or in stores, he said. "The way people shop and buy is changing rapidly."