People’s tendency to become more extreme after speaking with like-minded others has become known as “group polarization”...

“Views that would ordinarily dissolve, simply because of an absence of social support, can be found in large numbers on the Internet, even if they are understood to be exotic, indefensible, or bizarre in most communities,” Sunstein observes. Racists used to have to leave home to meet up with other racists (or Democrats with other Democrats, or Republicans with Republicans); now they need not even get dressed in order to “chat” with their ideological soul mates.
“It seems plain that the Internet is serving, for many, as a breeding group for extremism, precisely because like-minded people are deliberating with greater ease and frequency with one another,” Sunstein writes. He refers to this process as “cyberpolarization.”
Put the Web’s filtering tools together with cyberpolarization and what you get, by Sunstein’s account, are the perfect conditions for spreading misinformation. Who, on liberal blogs, is going to object to (or even recognize) a few misstatements about Sarah Palin? And who, on conservative blogs, is going to challenge mistaken assertions (or, if you prefer, lies) about President Obama?

MCCartney's barefoot appearance in the photo [on the cover of Abbey Road] sparked wild rumours the rocker had died in a car crash - and the 67 year old admits he still has to reassure some fans he's not an impostor.
He explains, "The idea was to walk across the crossing, and I showed up that day with sandals, flip-flops. It was so hot that I kicked them off and walked across barefooted, and this started some rumour that because he's barefooted, he's dead. I couldn't see the connection.

Q: So the tryptophan in turkey doesn't make you sleepy, right?

A: I am not sure how (that) gained wide acceptance. The urban legend is that the tryptophan in turkey is what makes you sleepy on Thanksgiving. Yes, the amino acid tryptophan is present in turkey, and in certain doses it can make you sleepy. But in reality, you'd need to eat an entire 40-pound turkey to get enough tryptophan to make a difference.

Q: So why do people take a nap on the couch?

A: It's probably more due to alcohol. Or it could be that you got up that morning early to travel. Or it's been a long, beautiful day, and you're just tired. I hate to even mention this, but I've seen claims that because you're increasing your carbohydrates, you're increasing your blood sugar, maybe this could lead to sleepiness. But I'm not sure I agree with that.

It has been demonstrated in both animal models and in humans that ingestion of a meal rich in carbohydrates triggers release of insulin. Insulin in turn stimulates the uptake of large neutral branched-chain amino acids (LNAA) but not tryptophan (trp) into muscle, increasing the ratio of trp to LNAA in the blood stream. The resulting increased ratio of tryptophan to large neutral amino acids in the blood reduces competition at the large neutral amino acid transporter resulting in the uptake of tryptophan across the blood-brain barrier into the central nervous system (CNS). Once inside the CNS, tryptophan is converted into serotonin in the raphe nuclei by the normal enzymatic pathway. The resultant serotonin is further metabolised into melatonin by the pineal gland. Hence, these data suggest that "feast-induced drowsiness," and in particular, the common post-Christmas and American post-Thanksgiving dinner drowsiness, may be the result of a heavy meal rich in carbohydrates which, via an indirect mechanism, increases the production of sleep-promoting melatonin in the brain.