Scientists are typically good at making scientific progress, but not particularly good at articulating what the progress consists of. - Alan Chalmers

The experienced and skilled observer does not have perceptual experiences identical to those of the untrained novice when the two confront the same situation.

Two normal observers viewing the same object from the same place under the same physical circumstances do not necessarily have identical visual experiences, even though the images on their respective retinas may be virtually identical.

A far as perception is concerned, the only things with which an observer has direct and immediate contact are his or her experiences.