Andreas Mojzisch and Stefan Schulz-Hardt (2010) presented people with information on prospective job candidates. People who received information on the group’s preferences before reviewing the candidate information, did not review the candidate information fully, and therefore did not make the best decisions. In a memory test they did not remember the most relevant information. The researchers concluded that when a group of people starts a discussion by sharing their initial preferences, they spend less time and less attention on the information that is available outside of the group’s preferences. And they therefore make a less than optimal decision.

https://www.blog.theteamw.com/2011/02/23/100-things-you-should-know-about-people-63-group-decision-making-is-faulty-2/