Kurosawa's style is marked by a number of devices and techniques. In his films of the 1940s and 1950s, he frequently employs the "axial cut", in which the camera moves toward or away from the subject through a series of matched jump cuts rather than tracking shots or dissolves. Another stylistic trait is "cut on motion," which displays the motion on the screen in two or more shots instead of one uninterrupted one. A form of cinematic punctuation strongly identified with Kurosawa is the wipe, an effect created through an optical printer: a line or bar appears to move across the screen, wiping away the end of a scene and revealing the first image of the next. As a transitional device, it is used as a substitute for the straight cut or the dissolve; in his mature work, the wipe became Kurosawa's signature.