The effect of social media use on children is a tense area of research, as parents and lawmakers try to determine the results of a vast experiment already in full swing. Successive studies have added pieces to the puzzle, developing the implications of a nearly constant stream of virtual interactions beginning in childhood.
A new study by neuroscientists at the University of North Carolina tries something new, taking successive brain scans of high school students between the ages of 12 and 15, a period of especially rapid brain development.
The researchers found that children who habitually checked their social networks around the age of 12 showed a different trajectory, with their sensitivity to social rewards from their peers increasing over time. Teens with less social media engagement followed the opposite path, with decreasing interest in social rewards.
The study, published Tuesday in JAMA Pediatrics, is one of the first attempts to capture changes in brain function related to social media use over a period of years.
The study has important limitations, the authors acknowledge. Because adolescence is a period of expanding social relationships, the brain differences could reflect a natural turn toward peers, which could be driving more frequent use of social media.
“We cannot make causal claims that social media is changing the brain,” said Eva H. Telzer, an associate professor of psychology and neuroscience at the University of North Carolina, Chapel Hill, and one of the study’s authors.
However, he added, “teenagers who routinely check their social networks show these quite dramatic changes in the way their brains respond, which could have long-term consequences well into adulthood, setting the stage for the development of brain over time.
A team of researchers studied an ethnically diverse group of 169 sixth- and seventh-graders at a rural North Carolina high school, dividing them into groups according to how often they reported checking their Facebook, Instagram and Snapchat.
Around the age of 12, the students already showed different patterns of behavior. Regular users reported checking their networks 15 or more times a day; moderate users consulted between one and 14 times; non-regular users consulted less than once a day.
The subjects received full brain scans three times, at approximately one-year intervals, while playing a computerized game that delivered rewards and punishments in the form of smiling or frowning peers.
While performing the task, the frequent checkers showed increased activation of three brain areas: reward-processing circuits, which also respond to experiences like winning money or taking risks; regions of the brain that determine salience, selecting what stands out in the environment; and the prefrontal cortex, which helps with regulation and control.
The results showed that “adolescents who grow up checking social networks more frequently are becoming hypersensitive to comments from their peers,” said the doctor. Telzer.
The findings do not capture the magnitude of the brain changes, only their trajectory. And it’s not clear, the authors said, whether the changes are beneficial or harmful. Social sensitivity could be adaptive, showing that adolescents are learning to connect with others; or it could lead to social anxiety and depression if social needs are not met.
Researchers in the field of social media cautioned against drawing sweeping conclusions based on the findings.
“They’re showing that the way you wear it at one point in your life influences the way your brain develops, but we don’t know how much, or if it’s good or bad,” said Jeff Hancock, founding director of the Media Lab. Social Sciences at Stanford, who was not involved in the study. He said many other variables could have contributed to these changes.
“What if these people joined a new team, a hockey team or a volleyball team, and they started having a lot more social interaction?” he said. It could be, he added, that researchers are “noticing the development of extroversion, and extroverts are more likely to check their social media.”
