Three recent studies point to the impact of social media and multiple device use on learning and cognitive control.
College students take years to learn to manage their social media so it doesn't impact their grades
A survey of 1,649 college students has found that freshmen average a total of two hours a day on Facebook, of which over an hour is spent also doing schoolwork, and that time spent on Facebook had a negative impact on their grade point average. For sophomores and juniors, only time spent using Facebook while doing schoolwork affected their GPA.
Seniors spent the least time on Facebook, the least time multitasking on Facebook, and their time on Facebook didn't affect their grades.
It's suggested that the difference between the year-groups has to do with the way the students interact with Facebook, and in particular, the students' ability to self-regulate.
Internet use during class impacts grades no matter how smart you are
An investigation into non-academic Internet use during an introductory psychology class has found that all students, regardless of their intellectual ability, were negatively affected by greater Internet use, with lower exam scores the more they used the Internet.
Not surprisingly (given other research showing that students are notoriously bad at appreciating good strategies or recognizing poor ones), the students themselves discounted such effects on their learning.
The study involved some 500 students, and used self-reports of internet use.
Given that this is an introductory class, we can safely assume most are freshmen.
A brain imaging study involving 75 adults has found that, independent of individual personality traits, people who frequently use several media devices at the same time had smaller grey matter density in the anterior cingulate cortex than those who use just one device occasionally. Functional connectivity between the ACC and the precuneus was also negatively affected.
The ACC is critical for cognitive and emotional control.
While it is possible that people with a smaller ACC are more likely to engage in such multitasking, the findings are consistent with other research showing that building expertise also builds gray matter in the relevant brain region (e.g., London taxi drivers building up the part of their hippocampus that deals with navigation), while gray matter can also shrink with disuse.
The findings are also consistent with evidence that individuals who engage in heavier media-multitasking perform more poorly on cognitive control tasks and exhibit more socio-emotional difficulties.
There's both positive and negative news in these reports:
positive, that students can eventually learn how to control their media multitasking (though the question occurs: is there a correlation between the students who drop out and those who can't learn the requisite cognitive control?)
negative, that failing to learn the requisite control may push the student into a negative feedback cycle, with their cognitive control network being eroded the more they continue to media multitask.
The negative scenario becomes even more likely for some individuals when you realize that those with the poorest control are unlikely to recognize their problem:
Poor multitaskers don't realize it
In 2013, I reported that college students who scored highest in multitasking ability were least likely to multitask, while those who scored lowest were most likely to engage in it. Last year, another study came out telling us that, while people generally realize that multitasking impairs performance, those who are worse at it don't realize it.
The study involved 69 volunteers who were given a visual tracking task, in which they had to keep a mouse cursor within a small target that moved erratically around a circular track. They also separately performed an auditory n-back task (a challenging working memory task). Before being asked to perform both tasks at the same time, they were asked to predict how much their performance would be affected.
Most people overestimated how much their performance would suffer. However, there was no correlation at all between individual predictions and performance, and those who were most affected showed no awareness that they were poorer than average at multitasking.
 . Student class standing, Facebook use, and academic performance. Journal of Applied Developmental Psychology [Internet]. 2015 ;36:18 - 29. Available from: http://www.sciencedirect.com/science/article/pii/S0193397314001257
 . Non-academic internet use in the classroom is negatively related to classroom learning regardless of intellectual ability. Computers & Education [Internet]. 2014 ;78:109 - 114. Available from: http://www.sciencedirect.com/science/article/pii/S0360131514001298
 . Higher Media Multi-Tasking Activity Is Associated with Smaller Gray-Matter Density in the Anterior Cingulate Cortex. PLoS ONE [Internet]. 2014 ;9(9). Available from: http://dx.doi.org/10.1371/journal.pone.0106698
 . Metacognition of multitasking: How well do we predict the costs of divided attention?. Journal of Experimental Psychology: Applied. 2014 ;20(2):158 - 165.