Online, Anonymity Breeds Contempt. A historical perspective on anonymity from an article on internet trolling on NYT.com in 2010.
BUT! Anonymity isn’t the only issue. Here’s a report from The Guardian in 2007 including this quote from Dr Chris Fullwood, “internet researcher”:
Removing anonymity may have some small effect, but not a massive one. This is because a number of factors contribute towards what psychologists call online disinhibition. Removing one of them - the anonymity - and not removing any of the others means it will probably still occur as people remain invisible and so can disassociate their online from their offline persona.
(note many of the links in the guardian article are broken/old!)