New research suggests that phones are altering fundamental aspects of social life. According to a study published in Computers in Human Behavior, strangers smile less to one another when they have their smartphones with them.

“Smartphones provide easy access to so much fun and useful content, but we wondered if they may have subtle unanticipated costs for our social behavior in the nondigital world. Smiling is a fundamental human social behavior that serves as a signal of people’s current emotions and motivations,” said study author Kostadin Kushlev, an assistant professor at Georgetown University.

In the study, pairs of strangers were assigned to wait together in a room for 10 minutes either with or without their smartphones. The room was videotaped, and the participants were positioned so that both of their faces were visible to cameras.

Participants with their smartphones were less likely to initiate conversations. Thirty-two participants who had their phones never ended up interacting with the other person in the waiting room. In comparison, just 6 people without their phones never interacted with the stranger.

The researchers noted that smiling only occurred when the participants actually interacted, so they excluded pairs of strangers who did not interact. That left them with data from 169 individuals.

“Smartphones made pairs of students smile less to each while waiting in a waiting room. People who waited with their phones displayed a genuine Duchenne smile about 30% less frequently than those waiting without their phones. This suggests that smartphones may impair opportunities to spark friendly conversations and build social ties with one’s peers,” Kushlev told PsyPost.

On average, those with their smartphones spent 103 seconds smiling, while those without their smartphones spent 149 seconds.

The study includes some limitations. For example, the participants were all college students. It’s also unclear if other technologies, such as televisions, would have similar effects.

There are also several areas for future research.

“We need to know why and how smartphones lead people to be less friendly to each other. What our data do seem to suggest is that even very minor, intermittent use (e.g. checking ones phone vs using it to do stuff) might be enough to produce less smiling between strangers,” Kushlev explained.

“In other words, it is not that people smile less simply because they are glued to their phones the entire time. A more likely mechanism is that even briefly looking at ones phone may send subtle messages of disinterest to others and/or impair conversation by offering a plethora of distractions.”

“Our findings point to the need for systematic psychological research on how human behavior is being changed by humans’ modern technological environment,” Kushlev added.

The study, “Smartphones reduce smiles between strangers“, was authored by Kostadin Kushlev, John F. Hunter, Jason Proulx, Sarah D. Pressman, and Elizabeth Dunn.