In recent years experiments have been performed on the influence on figural after-effect displacements of (a) the contrast between the inspection-figure and its background [(Nozawa (1953), Yoshida (1953), Pollack (1958)], (b) the width of the inspection-figure [(Kohler and Wa1lach (1944), Oyama (1955)], and (c) the background luminance of the inspection-figure [(Fujiwara and Obonai (1953)].The present account, which has been delayed, deals with research on the influences of these parameters.The results were first reterred to by Oyama (1954) according to the citation listed under E. H. Graham (1952) in the present table of references.See also the reference in Sagara and Oyama (1957).Despite the fact that a considerable time has elapsed since the completion of the experiments, it still seems desirable to present the results in published form.In particular they provide useful additions to the available evidence on three important influences on figural after-effect displacement. ApPARATUS AND PROCEDUREFor a detailed description of the apparatus employed to present figures to induce and to test for after-effects, the reader is referred to the Hammer article (1949).The test-configuration (T-figures) used in all the experiments was identical with that employed in the earlier work.The subject was asked to align vertically two black test-lines Tu and T A (each 3.4 mm X 0.6mm) while fixating a small black circle (3 mm in diameter) located (vertically) midway between them and centered at 2.2 mm to the right of their right edges.(See Fig. 1) Tu was aligned with TA (the latter being affected by the inspection-figure, ILl by means of the micrometer equipment described in the Hammer paper.