Superimposition

Superimposition is an editing technique and special effect that blends two or more shots (of separately photographed action). It does so on the same film strip in such a way that the images are seen simultaneously.

The technique of superimposition always draws attention to itself since it breaks up the apparent continuity of time and space. During a lap dissolve, one image is momentarily superimposed on another.

In contrast, however, a superimposition usually lasts longer than the blending of two shots in a lap dissolve. And unlike a lap dissolve, it usually does not signify a transition from one scene to another. Superimpositions are frequently used in montage sequences.