Back in 2014, David Broockman and Joshua Kalla, political scientists that now conduct their research at Stanford University and the University of California (UC), Berkeley, respectively, released a study in the journal Science that claimed that a short face-to-face interview with a gay canvasser can reduce people's prejudices.

Despite the findings intriguing social scientists everywhere, the team eventually found that their paper was ripe with discrepancies, and lead author Michael LaCour never produced the raw data to address them.

Cut to now when Broockman and Kalla released their own study that tests the same canvassing technique, only this time examining its effects on transgender people.

The results are, surprisingly, the same: the canvassing strategy can reduce biases.

"Journalists were still calling us about LaCour when the first wave of data were coming in from our study," Broockman said. "It was terrifying."

Regardless of skepticism, the current study uses reliable data and analyses.

"The data are solid and the analysis convincing," said Gabriel Lenz, a political scientist at UC Berkeley who verified the validity of the data, although he says that the effect is "so large and enduring that many researchers will be skeptical."

The team focuses on a persuasion technique created at the Los Angeles Lesbian, Gay, Bisexual and Transgender (LGBT) Center in California, which has been utilized in more than 13,000 face-to-face interviews over its 50-year history.

"Prejudice against transgender and gender-nonconforming people is a terrible daily reality," said David Fleischer, the center's director, which is why canvassers also make it their goal to permanently change the beliefs of the people they speak to.

The persuasion technique is called "analogic perspective taking," which asks a person to discuss an experience where they were perceived differently and treated unfairly, and then attempts to use this experience to generate sympathy for another group in this position, in this case transgender people.

"We knew from our own periodic attempts at self-measurement that we appeared to be achieving strong, lasting results," Fleischer said.

In the study, Broockman and Kalla sent 56 canvassers, some transgender and some not, to approach 501 people living in Miami. Some of the interviews focused on transgender discrimination and others on recycling, but all of them, which lasted 10 minutes each, contained a survey before and after to gauge people's beliefs on transgender people. Furthermore, follow-ups to took place up to three months later.

The results showed that the canvassing technique completely erased transgender prejudices in one in 10 people, and this change was strong enough to last at least three months. However, the results also showed that the prejudice reductions occurred regardless of the gender of the canvasser, suggesting that for the change to take effect, the interview needs to represent a victimized population.

"The findings are compelling, and it will be important to see how generalizable they are in future studies," said Diana Mutz, a political psychologist from the University of Pennsylvania.

Although the study points to the effectiveness of the analogic perspective taking method and the ability of face-to-face conversation to influence transgender prejudice, some are still skeptical of its long-term effectiveness.

"This study just showed that it could work; it didn't show exactly why it worked," said Elizabeth Levy Paluck of Princeton University. "That would be a great follow-up series of studies - to say, OK, what is the key ingredient of this canvassing conversation?"

The findings were published in the April 8 issue of Science.