  Social media usage has been shown to have both positive and negative
consequences for users' mental health. Several studies indicated that peer
feedback plays an important role in the relationship between social media use
and mental health. In this research, we analyse the impact of receiving online
feedback on users' emotional experience, social connectedness and self-esteem.
In an experimental study, we let users interact with others on a Facebook-like
system over the course of a week while controlling for the amount of positive
reactions they receive from their peers. We find that experiencing little to no
reaction from others does not only elicit negative emotions and stress amongst
users, but also induces low levels of self-esteem. In contrast, receiving much
positive online feedback, evokes feelings of social connectedness and reduces
overall loneliness. On a societal level, our study can help to better
understand the mechanisms through which social media use impacts mental health
in a positive or negative way. On a methodological level, we provide a new
open-source tool for designing and conducting social media experiments.
