A study suggests that schools should have a bit more control over cellphone use in the classroom, as researchers found that their presence may lead to lower test scores. 
The presence of laptops, too, was found to potentially lower test scores. Between the two devices, there’s just too much room for distraction.
Scientists have long studied the effects of divided attention in people, and they know that when someone’s attention is divided between 2 tasks, it’s harder for them to remember items regarding those tasks later on. This is known as “retention” in psychology.
There is also evidence to support that smartphones and other electronic devices reduce a person’s full thinking potential. Additional research from Stanford University shows that intense multitasking decreases the efficiency of completing a given task. 
Two previous studies point to poorer performance on exams when smartphones are present in the classroom, so a pair of researchers from Rutgers University decided to dig a little deeper into the link. 
Findings from the Most Recent Study
Dr. Arnold Glass, the lead researcher for the study and a professor of psychology at Rutgers University, said:
“I was always interested in using technology in the classroom before it existed, but when it became apparent that it was affecting the classroom, it raised the question [of] what effect this was having.”
The authors write in the journal Educational Psychology that students who had cellphones or laptops present during lesson time scored 5% – half a letter grade – lower on exams compared to students who didn’t use technology. 
Glass and his colleague separated 118 college students enrolled in the same course into 2 groups. The professor taught the same material to both groups, but one group was banned from using technology, while the other group was permitted to have cellphones and laptops open for non-academic purposes.
The students who were allowed to use electronic devices didn’t score lower on comprehension tests during lectures, but they scored lower on exams at the end of the term.
But in an odd twist, the students who didn’t participate in the study but were in the same classroom as the students who were allowed to use electronics also scored lower on exams, even if they weren’t using the devices themselves. Researchers say the presence of the devices was enough to distract them.
How can that be?
Truth be told, the finding is just another indication that you don’t have to be using a device to be distracted by it. A 2016 analysis of 20 previous studies found that merely having a smartphone or tablet in a child’s bedroom was enough to disrupt the child’s sleep and make he or she feel groggy the next day. The devices didn’t even have to be in use to subconsciously grab kids’ attention.
In 2017, researchers wrote in the Journal of the Association for Consumer Research that just having a smartphone within viewing distance lowers your cognitive capacity and overall brain power. In the study, people who kept their smartphone in another room, in their pocket, or in a bag performed better on tests than people who kept their smartphone within viewing distance.
The authors write:
“The intrusion of Internet-enabled electronic devices (laptop, tablet, and cellphone) has transformed the modern college lecture into a divided attention task.”
Glass says the study also applies to high school and middle school, as well as workplace meetings.
In a Rutgers University press release, Glass said:
“Many dedicated students think they can divide their attention in the classroom without harming their academic success – but we found an insidious effect on exam performance and final grades. To help manage the use of devices in the classroom, teachers should explain to students the damaging effect of distractions on retention – not only on themselves, but for the whole class.”
“These findings should alert the many dedicated students and instructors that dividing attention is having an insidious effect that is impairing their exam performance and final grade.” 
 ABC News