You’ve done it: driven back home to search for your forgotten phone. Dug under the car seats. Called yourself to find a lost phone. Or, worse, watched your phone ring silently when you were in a situation where you couldn’t answer it.

Cellphone use has become a common part of life as mobile devices have become one of the most popular ways to communicate. Research from the University of Missouri has found that cellphone separation can have serious psychological and physiological effects on iPhone users, including poor performance on mental tests.

The researchers say these findings suggest that iPhone users should avoid parting with their phones during daily situations that involve a great deal of attention, such as taking tests, sitting in conferences or meetings, or completing important work assignments, as it could result in poorer mental performance on those tasks. But use common sense and proper business etiquette about texting, talking, and checking emails in those venues.