How can you tell if they're into you? Look at how fast they respond to you

"We've all had the experience of clicking with some people but not others. We wanted to see if something in people's conversations reveals when they click," said Emma Templeton, a graduate student in psychological and brain sciences at Dartmouth and one of co-authors of the study. "Our results show that the faster people respond to each other, the more connected they feel."

The research, whose findings were recently published in the Proceedings of the National Academy of Sciences, consisted of three studies. The first one looked at response time and social connection between 66 strangers. They took part in ten conversations, during which they could discuss any topic of their choosing.

Their chat was videotaped so they could watch it back and rate how connected they felt moment by moment. Researchers found out that conversations with faster response times correlated with feelings of greater social connection.

Physical signs of attraction

They later tried to determine if these findings also applied to close friends. The response time data were similar- the more the conversation flows, the more participants felt connected to each other. "It's well-established that, on average, there's about a quarter of a second gap between turns during a conversation.

Our study is the first to look at how meaningful that gap is, in terms of connection," noted senior author Thalia Wheatley, the Lincoln Filene Professor in Human Relations at Dartmouth. "When people feel like they can almost finish each other's sentences, they close that 250-millisecond gap, and that's when two people are clicking."

Even more surprisingly, the study shows that outside observers also use response times to determine if two people have chemistry. You're at a party and you want to know if your friend is having a moment with this cute stranger they just met? Pay attention to the pace of their conversation. The faster they respond to each other, the more interested they are in making a connection.

Still not 100% sure? There are many more signs of a mutual attraction that you can look out for before making a move. A 2018 study, published in the journal Psychological Bulletin, found that people behave in specific ways when they're attracted to someone.