Instagram is exclusively image-driven, and images will crack your mirror.
"You get more explicit and implicit cues of people being happy, rich and successful from a photo than from a status update," says Hanna Krasnova of Humboldt University Berlin, co-author of the study on Facebook and envy.
"A photo can very powerfully provoke immediate social comparison, and that can trigger feelings of inferiority. You don't envy a news story."
Krasnova's research has led her to define what she calls an "envy spiral" peculiar to social media.
"If you see beautiful photos of your friend on Instagram," she says, "one way to compensate is to self-present with even better photos, and then your friend sees your photos and posts even better photos, and so on. Self-promotion triggers more self-promotion, and the world on social media gets further and further from reality."
Granted, an envy spiral can unspool just as easily on Facebook or Twitter. But for a truly gladiatorial battle of the selfies, Instagram is the only rightful Colosseum.
Instagram messes more with your sense of time.
"You spend so much time creating flattering, idealised images of yourself, sorting through hundreds of images for that one perfect picture, but you don't necessarily grasp that everybody else is spending a lot of time doing the same thing." Toma says.
Then, after spending lots of time carefully curating and filtering your images, you spend even more time staring at other people's carefully curated and filtered images that you assume they didn't spend much time on. And the more you do that, Toma says, "the more distorted your perception is that their lives are happier and more meaningful than yours".' Again, this happens all the time on Facebook, but because Instagram is image-based, it creates a purer reality-distortion field.
Instagram ups your chances of violating "the gray line of stalkerism".
"If you don't know someone, and Facebook is telling you that you have interests in common," says Nicole Ellison of the University of Michigan School of Information, "you can see their profile as a list of icebreakers." But that same profile is also a potential list of icemakers. If you meet a vague acquaintance at a party and strike up a conversation about a science article he posted to his Facebook wall, that probably seems normal. If you meet a vague acquaintance at a party and strike up a conversation about the eco-lodge he chose for his honeymoon in the Maldives, he will likely back away from you slowly.
"And then," Ellison says, "you've violated the gray line of stalkerism." Instagram's image-driven format gives you the eco-lodge but not the science article.
And arguably, you've violated the gray line of stalkerism simply by looking at those photos in the first place, even if you don't reveal yourself in public as the sad lurker that you are. Each time you swipe through more images of people's meals and soirees and renovation projects and holiday sunsets, you are potentially blurring the boundary between stranger-you-haven't-met and sleazy voyeur skulking around the cabana with an iPhone.
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