Mr. Fleischer wanted to study the effectiveness of his scripts, so he asked Mr. LaCour and Mr. Green for help; the research design was their idea. (Disclosure: I have collaborated with Mr. Green on other work and am the chairwoman of Mr. LaCour’s dissertation committee.) Most field experiments about politics randomly assign people to receive treatments and assess their effectiveness by using public information like voter registration or turnout records. This field experiment on Mr. Fleischer’s actively engaged conversation is different from nearly all the others that came before it in four ways.

First, Mr. LaCour and Mr. Green needed a way to track people’s attitudes, which meant they needed a survey. But the survey had to be ostensibly disconnected from the canvassing, or the subjects would be on to the test rather quickly. Mr. LaCour had the idea of impaneling people in Mr. Fleischer’s neighborhoods into a long-term survey about life in America. He also had the idea of targeting households with more than one registered voter so they could test the spillover effects of the treatment to other people in the house. Additionally, he raised enough money to keep the panel going for more than a year, which enabled tracking of people’s attitudes about same-sex marriage long after Mr. Fleischer’s team had come and gone.

There was one more innovation: In order to isolate the effects of witnessing a gay person coming out (the thing Mr. Fleischer believed would be the driving force in the method), Mr. LaCour proposed that some houses in the treatment group be visited by a gay canvasser and others by a straight one. (He randomly assigned which houses got which.) During the part of the script where gay canvassers came out as gay, the straight canvassers revealed a personal connection to a gay person: a son, daughter, brother, sister or friend.

The results were so striking that Mr. LaCour and Mr. Green immediately replicated them in full with additional canvassing, to verify the results were real and not obtained by chance.

When canvassers had emotional conversations with straight people who lived in neighborhoods that supported bans on same-sex marriage, they changed people’s minds — not only about same-sex marriage, but also about gays and lesbians as a group. However, these changes did not last as long for those who were canvassed by a straight person. Nor did they spread through the house to others. The changes in views induced by gay canvassers, however, lasted as long as the survey was in the field — nearly an entire year — and they influenced other people in the household, too.

Mr. Fleischer, Mr. LaCour, and Mr. Green have managed to demonstrate through research that connecting with another human being by sharing, listening, and showing vulnerabilities can lead to compromise. As we head in to the new year, with an increasingly divided government, they’ve also given politicians something to think about.