We’ve all been there. The boardrooms with flip charts at the front of the room and candy on the table. The all-hands emergency meetings to come up with ideas to fix the latest mess. And of course, the off-sites in drab hotel ballrooms that are supposed to somehow spark creativity.

Such efforts at brainstorming are well intended, of course. The problem? They rarely work. While leaders hang onto the idea that bringing together a big group of people will produce truly innovative ideas, it’s rare that actually happens.

Evidence has long shown that getting a group of people to think individually about solutions, and then combining their ideas, can be more productive than getting them to think as a group. Some people are afraid of introducing radical ideas in front of a group and don’t speak up; in other cases, the group is either too small or too big to be effective.

But according to a recently published study, the real problem might be that participants’ get stuck on each others’ ideas. On Monday, the British Psychological Society highlighted a recent study by Nicholas Kohn and Steven Smith, two researchers at the University of Texas at Arlington and Texas A&M University. They asked undergraduate students to contribute ideas for improving Texas A&M, both individually and in collective groups. They shared the ideas on a computer, either in small chat groups or alone, but combined together after the fact. As expected, the “nominal” groups, or those made up of individual ideas that were later pulled together, outperformed the real chat groups, both with the number of ideas and the diversity of them.

Kohn and Smith believed the cause might be because of “cognitive fixation,” or the concept that, when exposed to group members’ ideas, people focused on those and blocked other types of ideas from taking hold. They experimented with this by manipulating the number of ideas participants saw in their chat windows, with some getting a few cues and others getting more. Their hypothesis was right: When exposed to many cues, the undergrads offered up less creative, diverse ideas. The numbers improved when the students were given a five-minute break during the exercise.

As with all such studies, there’s plenty of pretty obvious common sense to this research. But it’s a helpful reminder of how unhelpful it can be when managers dump people in a room together, thinking it will result in creative big ideas. Somehow, a belief in the power of group brainstorming sessions persists, despite evidence that it doesn’t work. Great minds can come up with their own ideas, but sometimes the problem is they think too much alike.