The Anxious Generation: How the Great Rewiring of Childhood Is Causing an Epidemic of Mental Illness

by Jonathan Haidt

But even when students don’t check their phones, the mere presence of a phone damages their ability to think. In one study, researchers brought college students into the lab and randomly assigned them to (1) leave their bag and phone out in the entry room of the lab, (2) keep their phone with them in their pocket or bag, or (3) put their phone on their desk next to them. They then had the students complete tasks that tested their fluid intelligence and working memory capacity, such as by solving math problems while also remembering a string of letters. They found that performance was best when phones were left in the other room, and worst when phones were visible, with pocketed phones in between. The effect was bigger for heavy users. The article was titled “Brain Drain: The Mere Presence of One’s Own Smartphone Reduces Available Cognitive Capacity.” [48]