I've noticed that many people assume that consultants know more than they themselves do and/or more than their team does. That is, when a team is stuck on a problem, some people believe that a consultant can figure it out even without knowing that consultant. True, more heads might help, but I've also seen teams who believe everything a consultant says, especially at the beginning of the relationship yet scrutinize the people they work with. Why?
I've read about the halo effect in Wikipedia, which contains the statement, "The halo effect is a type of immediate judgement discrepancy, or cognitive bias, where a person making an initial assessment of another person, place, or thing will assume ambiguous information based upon concrete information."
This would suggest to me that any concrete information can bias someone when filling in the ambiguous information. However, reading more about the halo effect, it seems mainly focused on how people look.
So my questions are, what goes on in people's minds to create the belief that a consultant knows best when they don't have evidence to believe so? Is it a bias? If so, which one? Or just human behaviour? Something else? Does it depend on the situation?