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]
