The mere presence of your smartphone reduces brain power. Researchers conducted experiments with nearly 800 smartphone users in an attempt to measure, for the first time, how well people can complete tasks when they have their smartphones nearby even when they're not using them.

See the source article by following the link below:
The mere presence of your smartphone reduces brain power. Researchers conducted experiments with nearly 800 smartphone users in an attempt to measure, for the first time, how well people can complete tasks when they have their smartphones nearby even when they're not using them.