Research norms, looping in other researchers for ideas Let's say that I and a couple of a researchers have made good progress on some work but got stuck on something, say, a biological system that we derived but it's not quite working the way it should.  Would I be breaking any research norms by looping in one of my former professors (in the same department) who specializes in computational biology and can likely help us?  Or should I really let the advisor of our group decide on who to loop in for ideas and help?
This may be field dependent, but in my field (math), where groups of people that work on a paper together are rather small, you should ask all involved people before you enlarge the team. 

Note that there is a gray area, though. If you run into somebody and discuss your recent research and it seems like this discussion may be fruitful for the point where your team got stuck, it may or may not be a good idea to discuss your particular problem (depending on whether you know that guy before, there is a trusted relationship,…). When you are in this situation and are in doubt, you could resort to something like "It sounds like you could be the right person to discuss a particular problem we are having in our group. May I contact you later about this?" and then ask your group. In your situation, I would definitely ask the other group members before involving further people.