cyberdisinhibition

cyberdisinhibition
n. A temporary loss of inhibition while online. Also: cyber-disinhibition.

Example Citations:

According to the study, their world is expanding and narrowing at the same time because of social media's hyperlocalization quotient. And "cyberdisinhibition" — being more willing to behave online in ways they wouldn't in person — has both emboldened users and led them to inappropriate behavior.
—"Americans redefining their lives online and offline with social media tools," RISMedia, November 23, 2009

A recent study confirmed what we all suspect: The anonymity afforded by the Internet emboldens people to spread their inner creepiness. The authors of the study, published by Euro RSCG Worldwide, even coined a new term, "cyberdisinhibition," to describe the phenomena.
—Joe Livernois, "Joe Livernois: Wild Web deserves to be tamed," Monterey County Herald, January 24, 2010

Earliest Citation:

For what you are describing is the well-researched but under-reported phenomenon of cyber-disinhibition. Psychologist Daniel Goleman explains that it was noticed in the first days of the internet, then known as the Arpanet and used by a small group of scientists. They noticed "flaming," the tendency to send abrasive, angry and emotionally wild cyber-messages.
—"Blame cyber-disinhibition for inflaming e-rage," Canberra Times, March 7, 2006