Does social media make us more polarized?
Probably a little, but it's not clear why.
Social media usage appears to increase at least some forms of partisan polarization.
In the most direct evidence on this topic to date, Facebook users who deactivated their accounts were significantly less polarized with respect to policy issues while also exhibiting fewer negative feelings about the other political party, albeit to a lesser degree.
However, it remains unclear why social media polarizes its users along party lines.
Many pundits blame the creation of "echo chambers" on social media platforms, but the extent of these echo chambers may be overblown. It's also not obvious that social networks exacerbate echo chambers since, counterintuitively, they increase exposure to opposing views in absolute terms. Finally, researchers disagree about whether echo chambers even cause polarization in the first place. Exposure to opposing views on social media has been shown to decrease negative attitudes towards the opposing party, but some evidence suggests that it can inflame polarization as well.
One thing's for sure: social media is not the primary culprit for increasing animosity between parties. Polarization has increased the most amongst older Americans who are the least likely to use the Internet and social media.