The phone in the other room.

In the spring of 2017, four researchers asked roughly 800 people to put their phones somewhere before taking a test. Some were told to leave the phone face down on the desk. Some kept it in a pocket or a bag. The rest left it in another room. Every phone was set to silent, so nothing buzzed and nothing lit up. The participants then sat at a computer and worked through two standard measures of mental capacity, and the people whose phones were in the other room did best.

The paper was called “Brain Drain: The Mere Presence of One’s Own Smartphone Reduces Available Cognitive Capacity,” and it appeared in the Journal of the Association for Consumer Research. Its lead author was Adrian Ward of the McCombs School of Business at the University of Texas at Austin, working with Kristen Duke and Ayelet Gneezy of the University of California, San Diego, and Maarten Bos of Disney Research. It became one of the most cited findings in the popular argument about phones, and it is easy to see why. It seemed to prove something almost everyone already suspected, which is that the device does not have to be used to be in charge.

The design was cleaner than most in this field. In the first experiment, 520 smartphone users took the Automated Operation Span task, a test of working memory in which you hold letters in mind while solving arithmetic problems, and a short version of Raven’s Progressive Matrices, a classic test of fluid intelligence. In the second, 275 participants were sorted by phone location and by whether the phone was switched on or off. Turning the phone off did not help. What mattered was where it was.

The second experiment added a twist that deserves more attention than it got. The effect depended on how attached people were to their phones. Participants who scored high on a scale of smartphone dependence showed the largest drop when the phone was near, and those who scored low showed little. The phone was not a uniform tax. It charged most to those who had given it the most.

Ward’s explanation was that resisting the phone is itself work. As he put it to the university’s press office, “the process of requiring yourself to not think about something” consumes some of the mind’s limited resources. The phone does not need to ring. It sits on the desk as a standing temptation, and part of you stays on guard against it.

There was a further detail that made the study feel personal. When asked afterward, about three-quarters of participants said the location of their phone had not affected their performance at all. They were measurably worse and believed they were fine. That gap between what we feel and what we do is the most unsettling part of the paper, and it may be the most durable.

Psychology spent the 2010s learning that striking single experiments often fail to repeat, and the brain drain effect has had its turn. In 2022, Ana Ruiz Pardo and J. Paul Minda of Western University in Ontario published a preregistered direct replication of Ward’s second experiment in Acta Psychologica. They tested 383 students across the same six conditions, with phones on the desk, in a pocket or bag, or outside the room, and switched on or off. They found no difference between the phone locations on either working memory or response inhibition.

Meta-analyses, which pool many studies, have produced a quieter answer rather than a clean refutation. A 2023 review in Behavioral Sciences by Tobias Böttger, Michael Poschik and Klaus Zierer found a small overall negative effect of smartphone presence and use, with the clearest harm to memory and considerable variation from study to study. In 2024, Douglas Parry published a larger analysis in Media Psychology covering 56 studies and more than 7,000 participants. Only one effect held up. Working memory capacity was lower when a phone was present, while attention, inhibition and general performance showed no reliable effect. Parry described the support as limited, and the effect as smaller than the original theory proposed, and he noted that many of the studies were too small to settle the question.

So the honest summary is this. The phone on the desk probably costs something, the cost is modest, it seems to fall mostly on working memory, and it is not the dramatic drain the first headlines described. That is a less exciting finding. It is also a more believable one, and it happens to fit the most interesting part of the original paper, which was that the cost depends on the person.

Working memory is the part of the mind that holds a problem while you turn it over. It is where you keep the thread of a paragraph, the number you are carrying, the sentence the other person started before they paused. It is small, and almost everything that feels like thinking passes through it. A drain on it does not feel like distraction. It feels like being slightly less intelligent than you are, without knowing why.

The replication debate does not rescue the phone. It moves the question from the device to the relationship. If attachment is what drives the effect, then the phone on the desk is a measurement of something else, which is how much of your attention you have already promised away. A person who checks the phone every few minutes has trained a part of the mind to keep watch for it, and that watchman does not go off duty just because the screen is dark.

This is why the practical advice that follows from the research is so plain, and so often ignored. Put the phone in another room when the work matters. The location is the variable the original study manipulated, and it costs nothing to try. Turning it face down is a gesture. Turning it off, according to Ward’s own data, did not help. Distance did.

There is an older idea hiding inside this one. William James, writing in 1890, described attention as the mind taking possession of one object out of several possible ones. Possession is the right word. The generation that grew up with a controller in its hands knows the difference between holding a thing and being held by it, because a good game makes that difference the whole point. You choose to pick it up, and you can choose to put it down.

The smartphone was designed to blur that choice. The brain drain study, even in its humbler, replicated form, suggests the blur has a price, and that we are poor judges of what we are paying. The remedy it points to is not willpower. It is architecture, which in this case means a door, a drawer and another room.