Check out this interesting post by psychologist Daniel Goleman about the well known effect of electronic communication that allows people to say things online that they would never say in person.

A key mechanism for this involves circuits that ordinarily inhibit impulses for actions that would be rude or simply inappropriate — or outright dangerous.

In order for this regulatory mechanism to operate well, we depend on real-time, ongoing feedback from the other person. The Internet has no means to allow such realtime feedback (other than rarely used two-way audio/video streams). That puts our inhibitory circuitry at a loss — there is no signal to monitor from the other person. This results in disinhibition: impulse unleashed.