The web has made it straightforward, and depressingly frequent, to be nasty with out worry of repercussions – a scarcity of restraint that psychologists name on-line disinhibition impact, or ODE. Correspondent David Pogue talks with consultants who talk about why exchanges on social media can devolve into hateful, spiteful rages and name-calling that may by no means be acceptable when speaking face-to-face.