I only had time to briefly skim the study, but I don't think there was any follow-up done. Although it might immediately affect minority opinions to be reminded

I only had time to briefly skim the study, but I don't think there was any follow-up done. Although it might immediately affect minority opinions to be reminded of that, I would be much more interested to see if the group reminded of surveillance still kept their opinions to themselves a day, a week, a month later.