Can a phone on your desk make it harder to think, even if you do not touch it? A 2017 study said yes. Students with their phones on the desk did worse on tests than students who left their phones in another room.

But later, other scientists did the test again and found no difference. Messages and quick checks do break your focus, though. So put your phone in another room.

In 2017, Ward and colleagues reported a surprising "brain drain" effect. University students put their smartphones on the desk, in a bag or pocket, or in another room, and then took tests of working memory.

Students with phones on the desk scored lowest, and those whose phones were in another room scored highest. In 2022, however, researchers in Canada repeated the experiment. They published their plan in advance and found no difference.

A 2024 meta-analysis of 33 studies also found that the mere presence of a phone had almost no effect. Notifications are another matter. A 2015 study showed that simply receiving one increased mistakes on an attention task. Keeping your phone in another room is an easy choice.

In 2017, Ward and colleagues published a study suggesting that the mere presence of one's own smartphone reduces available cognitive capacity. Students who kept their phones on the desk performed worse on tests of working memory and reasoning than those who left their phones in another room, and the effect was stronger among people highly dependent on their phones. The finding, dubbed "brain drain," attracted wide attention.

However, later evidence has been far less clear. In 2022, a preregistered direct replication by Ruiz Pardo and Minda found no effect of phone location. Two meta-analyses followed. One, covering 33 studies and roughly 4,400 participants, estimated the effect of mere presence at essentially zero.

Another, covering 56 studies, found a small negative effect on working memory only, but warned that many studies lacked statistical power and used different methods. A third meta-analysis concluded that the overall effect was harmful, showing how conclusions can depend on which studies are included. What is better supported is that interruptions matter: a 2015 study found that merely receiving a notification increased errors on an attention task. The safest advice, therefore, is to silence notifications and keep the phone out of reach while studying.