A 2021 study suggests the same psychological phenomenon that makes yawns contagious also affects people to check their smartphones.
We subconsciously follow the norms imposed on us by people around us and match our actions with theirs, known as the chameleon effect. This is why people often pick up each others' mood during conversation or why yaws are so contagious.
Most people are susceptible to the chameleon effect's impulse to pick up and look at their phone when someone else is doing it.
Research found the odds that people would use their phones are about 28 times higher when the first user actually looked at their phone while they used it, compared to when a person just held the phone and tapped without looking. But when people were at a meal, they were less likely to check their phones after a trigger event.