'Some aspects of modern life can make you lose the will to live. Of all the bad trips new tech invites us to take, none feels more hellish than the website 'discussion thread' on any hot topic of the day. Who let these rabid dogs out? Why does online 'debate' so often leave the browser with a turned stomach and a soiled soul? Because, perhaps, networked shouting-matches that encourage players to cuddle their imaginary friends and demonise their equally disembodied foes bring to a peak the dynamics of 'group polarisation' explored in this timely and absorbing book...'