Turn off non‑essential notifications and keep your phone out of sight while working

Cost: No cost at all. It takes just a few minutes to adjust the settings, and hardly any willpower is required.
In plain terms: Even if you don’t look at or touch your phone when it rings, your performance on attention‑related tasks still drops. The drop is roughly the same as when you actually answer calls or send messages. Another scenario: even when the phone sits on the desk and you resist the urge to glance at it, the amount of mental capacity available still decreases. The more dependent a person is on their phone, the greater this drop tends to be.
Benefit: Merely receiving a notification — without looking at or interacting with the phone — noticeably impairs performance on attention tasks. The degree of impairment is comparable to actually answering calls or sending messages. These findings come from laboratory studies involving university students. Two additional experiments also show that even when participants successfully refrain from looking at their phone, having it nearby still reduces their available mental resources; this effect is strongest among heavy phone users.
Evidence grade: B
Sources:Stothart, Mitchum & Yehnert (2015). The attentional cost of receiving a cell phone notification. Journal of Experimental Psychology: Human Perception and Performance. https://doi.org/10.1037/xhp0000100；Ward, Duke, Gneezy & Bos (2017). Brain Drain: The Mere Presence of One's Own Smartphone Reduces Available Cognitive Capacity. Journal of the Association for Consumer Research. https://doi.org/10.1086/691462
Notes: All of these results are based on single‑task experiments conducted in a lab setting. No research has examined how these effects accumulate over days or weeks in real‑world conditions. For jobs where immediate responsiveness is essential, it may be advisable to allow notifications only from a limited set of contacts.