If you have a hard time changing your opinion, that's fine and even normal. As an INTP, I can be stubborn with my ideas sometimes, but I would say that what I consider open-mindedness is to entertain any conflicting opinions and THEN discard them after analyzing them more thoroughly. If they still seem problematic that is. My mindset is that even some random person that knows little of the subject might have a point sometimes. So simply put: do not reject different opinions too quickly.
But if what the person is saying is something you already considered and so you kind of ignore it, then that is not being close-minded.
But if what the person is saying is something you already considered and so you kind of ignore it, then that is not being close-minded.