However, labeling inaccurate posts as being humour, parody or a hoax did help and resulted in significantly less willingness to share such posts.
"We thought that fact-checking flags might work pretty well on Facebook, but that's not what we found," said R. Kelly Garrett, lead author of the study and professor of communication at Ohio State.
It only helped to have flags for satirical posts.
"This raises some really interesting questions about why people are moved to disbelieve a claim when you tell them it is hoax or satire, but not when journalists or even their peers say there is something wrong with the story," Garrett said in a paper published online in the Journal of Computer-Mediated Communication.
To reach this conclusion, the researchers conducted two separate studies.
In the first, 218 participants completed a brief questionnaire that included measures of their positions, knowledge and beliefs about several political topics, as well as their political ideology, party affiliation and demographics.
Participants were shown two Facebook posts with the inaccurate statements that they were asked about two weeks earlier (illegal votes cast in the 2016 election and Russian vote tampering).
Results showed that people who received the flags saying fact-checkers or their peers disputed the post still believed the falsehoods just as much as they did earlier. Further, they were still likely to say they would share the false information.
But the people who received the flag saying the post was meant as humour were more likely to change their minds. They were less likely to believe the falsehood and were less likely than others to say they would share it.
"There's little reason not to label satire. The best jokes are still funny even when you know they're jokes. More importantly, labeling can help people who might otherwise be misled," said study co-author Shannon Poulsen.
The researchers did a second study, with a larger (610 people) and more demographically diverse sample. The study was similar, although not exactly the same, and had the same general results.
Garrett said he suspects that one reason the satire flags worked is that they told people why a certain statement was false -- because it was meant as humour.
"When you just say a claim is false, you haven't really given an explanation for why," he said.
"People respond to stories. They want to know why something is being called inaccurate," Garrett added.