Republican nominee Donald Trump and Democratic nominee Hillary Clinton speak during the first presidential debate Sept. 26. (Paul J. Richards/Agence France-Presse via Getty Images)

Deborah Tannen is a linguistics professor at Georgetown University and author of “You Just Don’t Understand” and “The Argument Culture.”

Interruptions are a staple of modern-day political debates, as we saw in the first presidential and the vice-presidential face-offs. Judging by the column inches, screen space and private conversations devoted to these interruptions, it’s clear that many viewers expect candidates to speak only during their allotted time. But that is no longer the norm. In the past, great communicators were great orators, but great communicators today sound conversational, and interrupting is common in conversation. And public discourse is now more about entertainment than enlightenment. For better or worse — better from the perspective of entertainment, worse for enlightenment — the announced formal structure of presidential debates has given way to rule-breaking interruptions. The question now is not whether candidates interrupt, but when and how, the frequency and why they do so.

One of the most commented-on elements of the first presidential debate was the imbalance: Trump interrupted Clinton 51 times — 25 times in the first 26 minutes — while she interrupted him only 17, according to Vox. Would Trump have used the same tactics had his opponent been a man? And would the moderator have stepped in more forcefully and more often had it been Clinton who was interrupting Trump?

It’s not that men never interrupt other men; after all, Trump interrupted his opponents in the primary debates, too. It’s that women are interrupted more. The interruption imbalance was also striking in Matt Lauer’s commander in chief forum interviews of Clinton and Trump, as the American Enterprise Institute commentator Norman Ornstein tweeted: “Lauer interrupted Clinton’s answers repeatedly to move on. Not once for Trump. Tough to be a woman running for President.” There is ample evidence for this view in research — and history.

One of the first studies in the field of gender and language, by Don H. Zimmerman and Candace West in 1975, found that in casual conversations between women and men, women were interrupted far more often. And in 1982, the University of Sheffield psychologist Geoffrey Beattie found that British Prime Minister Margaret Thatcher was interrupted far more often than male senior politicians, and that she interrupted others far less frequently as well. Years ago, when I was a guest on his one-on-one interview show, John McLauglin showed me video clips to illustrate a pattern he’d noticed on “The McLaughlin Group”: that panelist Eleanor Clift was interrupted far more often than her male counterparts.

The vice-presidential debate was revealing in this regard. Democrat Tim Kaine interrupted Republican Mike Pence more often than the reverse, but Kaine’s 70 interruptions were less than double Pence’s 40, whereas Trump’s and Clinton’s were far more imbalanced.

Not all interruptions are created equal. It might seem at first surprising that when I studied women and men talking at work, I found that women “interrupted” each other more often than men did — when they were in all-women conversations. I put the word “interrupted” in quotes because an interruption is a violation of turn-taking rights: A second speaker tries to steal the floor when a first has a legitimate claim to it. But the talking-along I observed in all-women conversations was typically intended to show enthusiastic listenership. I call these “cooperative overlaps,” because they function like a cheering squad, encouraging the speaker to keep going.

None of Trump’s interruptions of Clinton were cooperative, but not all of them were floor-stealing, either. To be sure, some were, as when he talked over her at length. But at other times his interruptions were more like interjections, as when he belted “Wrong!” while Clinton spoke. Quite different were quips to comment on how she was characterizing him. The opposite of “Wrong!,” these quips implied, “Right! And it’s a good thing, too!” Many felt that these interjections damaged Trump, by reinforcing Clinton’s suggestion that he didn’t pay any taxes (“That makes me smart”) or that he celebrated the housing crisis because it meant he could buy up property on the cheap (“That’s called business”).

An assumption underlying almost all comments on interruptions is that they are aggressive, but the line between what’s perceived as assertiveness or aggressiveness almost certainly shifts with an interrupter’s gender. When both debaters are men, they may gamble that it’s worth interrupting to come across as bold and assertive. But a woman must be more cautious: Just as we know that men tend to interrupt women more often than the reverse, we also know that when women interrupt men, they are judged more harshly.

If the goal of interruption is to grab the floor, Trump’s worked. According to ABC News, he ended up with more than 3 minutes more airtime than Clinton: 45 minutes and 3 seconds to her 41 minutes and 50 seconds. But the tactic backfired: Although Trump won the competition for talk time, it was generally agreed that he lost the debate. His lopsided interruptions were not the main reason, but they surely played a role.

The townhall meeting format of Sunday night’s debate will add layers of meaning to interruptions. It seems unlikely that questioners will be interrupted, because they represent the voters who are watching, and no one wants to offend them. But cutting off a candidate who is answering a voter’s question might seem disrespectful to the questioner, too. What we know for sure is that there will be interruptions — and how people judge them will no doubt vary, too.