Over the past 50 years, we’ve seen a number of gigantic policies produce disappointing results — policies to reduce poverty, homelessness, dropout rates, single-parenting and drug addiction. Many of these policies failed because they were based on an overly simplistic view of human nature. They assumed that people responded in straightforward ways to incentives. Often, they assumed that money could cure behavior problems.

Fortunately, today we are in the middle of a golden age of behavioral research. Thousands of researchers are studying the way actual behavior differs from the way we assume people behave. They are coming up with more accurate theories of who we are, and scores of real-world applications. Here’s one simple example:

When you renew your driver’s license, you have a chance to enroll in an organ donation program. In countries like Germany and the U.S., you have to check a box if you want to opt in. Roughly 14 percent of people do. But behavioral scientists have discovered that how you set the defaults is really important. So in other countries, like Poland or France, you have to check a box if you want to opt out. In these countries, more than 90 percent of people participate.

This is a gigantic behavior difference cued by one tiny and costless change in procedure.

Yet in the middle of this golden age of behavioral research, there is a bill working through Congress that would eliminate the National Science Foundation’s Directorate for Social, Behavioral and Economic Sciences. This is exactly how budgets should not be balanced — by cutting cheap things that produce enormous future benefits.