Omission of the unfamiliar is also frequent. It differs from omission of the irrelevant, in that it has nothing whatever to do, of necessity, with connexions between parts of presented material. This becomes the more clear upon the consideration that when incidents, objects, or events unfamiliar in themselves, are nevertheless related to anything that is familiar, what frequently occurs is not omission but transformation. A special case is where that which is unfamiliar in itself is rendered familiar by its content. It is then frequently preserved, but transformed. Thus in my reproductions, "boats" invariably sooner or later replaced "canoes," and "rowing" replaced "paddling"; a "bush-cat" became an ordinary "cat," and "pea-nut" was transformed into "acorn." It is in this type of change that the direct influence of social and environmental factors is probably the strongest.
Omission of the unpleasant was very frequently illustrated. This needs little emphasis, as the principle is now well established. Several of the stories used were chosen purposely because they contained modes of speech, or reports of incidents somewhat opposed to modern conventions. Such modes of speech, and such relatively shocking incidents, always tended to disappear. This also was very marked when, in repeated reproduction, the intervals were extended. The material simply disappeared from the reproduction, leaving the subject entirely unaware that anything had dropped out. There is more than a little suggestion that material thus omitted may still have continued to exercise some influence in giving a new twist to the reproductions. Such functioning of factors from the Unconscious is of particular interest in view of the development of contemporary psychology.
When we turn from omissions to transformations we find that here, also, the influence of three broad principles of change is evident. The first may be called the principle
