At its best, psychological science transparently puts big competing ideas to the test. With varied methods and with replication of noteworthy findings, it winnows truth from the haystack of mere speculation. If the evidence supports an idea, so much the better for it. If the idea collides with a wall of fact, then it gets rejected or revised.
In reality, psychology often falls short of this ideal. A noteworthy finding doesn’t replicate. Confirmation bias drives a researcher to selectively attend to supportive evidence. In rare cases, researchers have stage-managed desired results or even faked data.
Yet the psychological science ideal is achievable. My social psychologist colleagues Jonathan Haidt and Jean Twenge exemplify this ideal as they assemble evidence regarding social media effects on teen mental health, and invite others to critique and supplement their data. “It is amazing how much I have learned, and refined my views, just by asking people to make me smarter,” Haidt has told me.
The stimulus for their work is a troubling social phenomenon: As smartphones and social media use have spread among teens, teen depression has soared, especially among girls. Moreover, youth hospitalization for "attempted suicide or self-injury increased from 49,285 in 2009 to 129,699 in 2019." The CDC’s 2023 Youth Risk Behavior Survey report illustrates:
Is this simultaneous increase in social media use and teen depression a mere coincidence?
Given that plausible other factors such as economic trends, wars, or domestic violence seem not to account for the decade-long trend, Haidt and Twenge conjectured a plausible culprit: the shift from face-to-face relationships to screen-based relationships, with in-person time with friends dropping by more than half since 2010. More time online has also displaced sleep and play. And it has increased demoralizing social comparisons. As Cornell University’s Sebastian Deri and his colleagues found across eleven studies, most of us, in the age of selfies, perceive our friends as having more fun: Other folks seem to party more, eat out more, and look happier and prettier.
Even teens not on social media are likely affected, Haidt notes. When friends are interacting online several hours a day, those not similarly engaged can feel left out and isolated.
To assess their presumption of social media harm, and mindful of lingering skepticism, Haidt and Twenge assembled the available evidence from four psychological science methods: correlational, longitudinal, experimental, and quasi-experimental.
Correlational: First, they asked, do daily social media hours correlate with teen mental health? In a recent Substack essay, Haidt notes that 80 percent of 55 studies answered yes. The correlation is modest when summed across genders and all forms of screen time, but becomes telling when, as shown in these UK data, one spotlights girls’ social media exposure.
Longitudinal: Second, they asked, does social media use at Time 1 predict mental health at Time 2? Among 40 longitudinal studies, Haidt reports, in 25 the answer was yes. For example, in a new study reducing social media use proved “a feasible and effective method of improving body image” among vulnerable young adults.
Experimental: Third, they asked, do experiments that randomly assign participants to social media exposure produce a mental health effect? In 12 of 18 experiments, mostly done with college students and young adults, the answer was, again, yes. Moreover, among the six studies finding no effect, four involved only a brief (week or less) social media diet.
Quasi-experimental: Finally, they asked, do quasi-experiments find that the timing of social media arrival predicts mental health? Was the rollout of Facebook on a campus or the arrival of high-speed internet in a community followed—at that location—by increased mental health problems? In all six studies, Haidt reports, “when social life moves rapidly online, mental health declines, especially for girls.”
Together, these correlational, longitudinal, experimental, and quasi-experimental findings illustrate how psychological science explores life-relevant questions with multiple methods. Moreover, the diverse findings weave a compelling answer to the social media–teen mental health question. In the words of Haidt’s Substack title: “Social Media is a Major Cause of the Mental Illness Epidemic in Teen Girls. Here’s the Evidence.”
Would you agree with Haidt’s conclusion? If yes, would you also agree with recent bipartisan calls to restrict social media to those over 16? Would doing so be supportive of parents, teens, and schools—much as efforts to restrict teen smoking have effectively dropped teen smoking from nearly 23 percent in 2000 to 2 percent in 2021? Would you concur with researchers who advise parents to keep phones out of teens’ bedrooms at night?
If you are a teen, does this research have any implications for your and and your friends' mental health? Should teens begin smartphone use with texting rather than with selfies and social media? Should they intentionally restrain their daily hours online?
And if you don’t agree that social media are a “major cause” of teen girls’ increased depression, what would be your alternate explanation?
The importance of these questions, for teens, families, and society, will drive further research and debate. In the meantime, the complementary insights gleaned from these correlational, longitudinal, experimental, and quasi-experimental studies showcase, methinks, psychological science at its best.
(For David Myers’ other essays on psychological science and everyday life, visit TalkPsych.com or his new essay collection, How Do We Know Ourselves: Curiosities and Marvels of the Human Mind. Follow him on Twitter: @davidgmyers.)
