People have a harder time coming up with options when in a group than when alone. It apparently has something to do with repetition. Meetings do foster discussion of issues, but the more than a particular solution is said out loud, the harder it is to think of other ideas.
The researchers speculate that when a group of people receives information, the inclination is to discuss it. The more times one option is said aloud, the harder it is for individuals to recall other options, explained Krishnan, associate professor of marketing at Indiana University.
I've seen this happen in meetings -- one idea is discussed endlessly, and when the group finally gets around to talking about other options, people are fixated on the first idea that was talked about.Heck, I've used this to my advantage in meetings where I want the group to do things my way. Persuasively present the preferred solution...and then ask for other ideas. People gravitate back to the same solution, as if it gets stuck and is somehow validated, because they simply can't think of other options when they are saturated with discussion about the first solution. People fall into "groupthink" because it is self-supporting: get approval and positive reinforcement for reiterating the ideas of other, and eventually they seem like the right choice.
Interesting that someone has proved that it is a consistent effect, though.