As human beings we are programmed to be acutely aware of changes in our environment. We take in new information automatically and process it according to our own values and experiences.
In photography the photographer adjusts filters, softens or distorts the picture. The frames dictate what is seen. Further changes to the frame or applying a new filter make the picture different. To some the picture is better, maybe the definition is clearer. To others the picture is worse, it may lack depth.
In mediation, every participant is looking through their own lens. Their views are usually different, sometimes poles apart, maybe even conflicting. The participants, including the mediator, should acknowledge that each lens is unique and differs from the other. Once participants appreciate that they are looking at the same picture but with different views that same picture can be brought into focus and resolution can be found.