A nice little article on the Harvard Business Review blog from McKinsey highlights essentially the idea that most of us are predisposed to rate ourselves better than our peers, direct reports, etc especially in behaviour-related areas and how 360 degree feedback looks to redress this 'self-serving' bias.
It is along the lines of 'It's not me, it's all them others...', a tendency to not perceive ourselves as part of a problem; as a group in an organisation we might all recognise the issue or problem, but the fail to see how we might contribute to it through our own behaviour....hmmm, now where have I heard that recently in the news?
It reminds me of the wonderful road sign in Germany which is placed by areas of high traffic congestion which says 'You are not in traffic, you are traffic'.
John