Sharing is caring: How sharing opinions online can connect people into groups and foster identification.

Computer mediated communication has marked differences from the face-to-face context. One major difference is that, in the online context, we often have explicit access to others' opinions and these opinions are often the only informational cues available. We investigate if awareness of opinion congruence, in the absence of any other reference categories, may be sufficient to foster social identification. In a pre-registered experiment (N = 681), we manipulated exposure to opinions, and measured levels of ingroup identification, opinion-based identification and their social influence on activism intentions. Our results demonstrate exposure to others' opinions in an otherwise anonymous context fosters ingroup and opinion-based identification. There was no effect on opinion-based group activism intentions. We conclude that computer mediated contexts have consequences for identification - opinion (in)congruence is becoming more relevant as a source of social categorization. While we did not find this identification had a social influence on activism, we discuss avenues for future research to disentangle the features of opinion-based groups necessary to foster activism.