In many modern building complexes the problem of disorientation is acute. People have no idea where they are, and they experience considerable mental stress as a result. This is because many modern buildings do not have features that are readily recognized and remembered by people trying to find their way about. Nor are they grouped in such a way that a person sees a recognisable entrance, or central part of the building, to which he can relate the other parts. Psychological theory suggests that the effect of a badly laid out building is almost as bad on a person who knows it as on one who does not, since he spends a good deal of time looking out for landmarks and wondering where to go next, and his minds is generally distracted by the excessive attention he has to pay to the building. It is also important that names be used to distinguish parts of buildings, and also colours, and that the sizes of different parts of the building indicate the relative importance of each part. A good environment is one which is easy to understand, without conscious attention: for example, an Oxford or Cambridge college has a system of groupings that are easily recognized and remembered, being made up of 'courts', 'staircases', 'rooms', etc, which are easily identifiable.