Absolutely fascinating look at the neuroscience that underlies behaviour patterns on Twitter and other forms of social media:
Researchers have previously shown that certain online activities--such as checking your e-mail or Twitter stream--stimulate the brain's reward system. Like playing a slot machine, engaging in these activities sends the animal brain into a frenzy as it anticipates a possible reward: often nothing, but sometimes a small prize, and occasionally an enormous jackpot. The response to this unpredictable pattern seems to be deeply ingrained, and for the most basic of reasons: precisely the same cycle of suspense and excitement motivates animals to keep hunting for food.
Twitter is feeding sweet dopamine crack straight into your pleasure centres...
Update: Steve Ranger has pointed me to his useful piece on the various research approaches being taken into the impact and power of social media on psychology. Nice to see some rigour being applied to the generic posturings of the social media gurus... ;-)