“The goal is to help people who want to take a given step but may face some barriers,” said Maya Shankar, the Oxford-educated scientist who leads the team. “You can do everything to make sure that a program is well designed, but if it’s not getting into the hands of people who are supposed to be benefiting from it, everything up to that point was for naught.”

Governments generally operate on the assumption that people are rational. One of the basic implications of mainstream economic theory is that public policy works best when people are treated as rational decision makers.

Yet a growing body of research has found that people are not only irrational on occasion, but they tend to be irrational in some consistent and predictable ways. People tend to be influenced by the last thing they heard. They tend to fear losses more than they like profits. They tend to be a little lazy.

And researchers from this new school argue the government should account for these tendencies.

“Almost any domain that they let us go in, we could figure out some way of making at least modest improvements in what they’re doing,” said the University of Chicago economist Richard Thaler, one of the founders of behavioral economics and a leading advocate of governments making use of what he calls “nudges.”

Ms. Shankar and her team of 15 — including psychologists, economists and sociologists — conducted about a dozen experiments over the last year to prove the value of the approach, but so far the successes remain small. The rebate forms, for example, increased revenue by about 6 percent.