I'm not sure if this is a logical fallacy per se, but I have observed some very strong groupthink effects with respect to voting dog piling, both for positive a

I'm not sure if this is a logical fallacy per se, but I have observed some very strong groupthink effects with respect to voting dog piling, both for positive and negative votes. Strongly postive comments and stories tend to have accelerating up voting rather than the expected fixed frequency of votes, implying that number of votes is itself a factor for some in deciding whether to vote for something. It shouldn't be.