Who's really going to vote "Yes" even if they would in reality fall victim to "group think" in certain situations?? No one. That's the thing, seldom is "group think" voluntary or done through one's own consciousness.
"There is no god; there is only us. Savage and fragile."
Believe it or not, your participation on the internet is one of increased group cohesiveness. Would you prefer to go without the internet and books to increase the independence of your analysis?
To completely avoid the influence of group think, one must be completely isolated from all other human beings - no language. I'm not saying this would be all bad, but it would certainly be challenging.