Sometimes you meet someone and feel instantly in sync. Conversation flows effortlessly, as if you can finish each other’s sentences. It is hard to predict when it will happen, and, in fact, such connection is so rare and mysterious that at times it can seem illusory — perhaps now more than ever in these masked and socially distanced times.

In a study we recently published, however, we showed that there is an objective measure of when two people are connecting, a sort of “tell”: The gaps between their conversational turns shrink.

Though most of us rarely think about it, two-way conversations represent a remarkable feat of coordination. People are able to respond to each other remarkably quickly, in about 250 milliseconds, or a quarter of a second, on average. Each person absorbs what the other says and formulates a response in the blink of an eye. Shrinking that gap further requires an even more remarkable attentiveness to what the other person is saying. These speeds are too short to be under conscious control, meaning they are what biologists call an “honest signal.”

Our central finding was that people report greater enjoyment, and a greater sense of connection, when the gaps in their conversation were shorter. (To put it another way, close conversations naturally feature shorter gaps. But there were other intriguing findings, too. Some people, for example, seemed to have a particular gift for swiftly absorbing other people’s points and responding in kind. They responded more quickly than their peers, across numerous partners — and they left a feeling of warmth in their wake. Unfortunately, as we’ll explain, there’s unlikely to be a shortcut for emulating these conversational rapid responders.

How did our study work? First, we asked pairs of participants — drawn from a 66-person sample — to have 10-minute conversations about whatever they wanted. Most had never met each other. We recorded the conversations and measured the intervals between each speech turn. In a variation on this experiment, we brought some of the same people back but paired them with friends of theirs.

Afterward, in both cases, the participants entered separate rooms and watched the interactions on video while moving a slider to indicate how connected they had felt, moment by moment. Even within a single conversation, the moments when people felt especially connected were characterized by shorter gaps than at other times. Few people will be surprised to hear that conversations have this kind of ebb and flow.

In any conversation, two people are contributing to the average gap between turns. Do these contributions matter equally? The answer, we found, is no: The degree to which people felt connected was much more dependent on how quickly the other person responded to them. How quickly they themselves responded made much less of a difference.

Our studies also found that outside observers, too, perceive shorter gaps in conversation as an indicator of social connection. To explore this question, we took snippets of six different conversations between strangers and manipulated the size of the gaps with audio software. We assigned participants on a crowdsourcing platform to listen to one of three versions of each conversation: one edited so that the gaps were doubled, one in which gaps were one-fifth the original length, and the original exchange. Across all the conversations, the shorter the gaps, the more the outside observers thought the two partners seemed connected. Since the only things that varied in these conversations were the gaps, we know that short gaps alone are a sufficient signal of perceived closeness. (Presumably there’s a point at which a response seems too quick — rudely abrupt and possibly off the point. But we did not study that phenomenon.)

As mentioned, we did find some people whom you might call super-connecters — those who tended to respond more rapidly to others, no matter their partner, and who therefore instilled feelings of connection in others. Could it follow that people without this natural ability could simply decide to speed up their own response time and have the same effect?

Not really. Because humans can’t just edit down gaps in their conversations (unless you’re a researcher working with an audio file). The only way to respond quickly is to understand where the other person is coming from and to anticipate where they are going. Sometimes that happens effortlessly — we fall immediately into step, minds dancing together in a kind of flow state. Other times it requires slowly moving toward that point through active listening and getting to know each other (gradually learning new dance steps). You can’t simply will conversational connection into existence.

When we talk about intimacy, we tend to use distance words: We say we are “close,” “tight,” “joined at the hip”; we say that someone is part of our “inner circle” This set of studies shows that how we talk to each other also telescopes the space between us. Responding quickly to our partners makes them feel closer. By shrinking the space between our turns, we shrink the psychological distance between us.

Thalia Wheatley is the Lincoln Filene professor in human relations at Dartmouth College and external professor at the Santa Fe Institute. Emma M. Templeton is a graduate student in psychological and brain sciences at Dartmouth College.