A method is suggested to deal with a rather urgent task of selecting people who can easily visualize the problem situation and who can efficiently transform corresponding visual representations. The primary task in developing the method consisted in establishing the outward indicators of the mental visualization. Some general mechanisms of visualization and of fixation of after-images stable in relation to the retina have been found. Criteria for testing individual differences in the efficiency of the representational thinking are suggested, as well as some procedures helpful in promotion of the ability to visualize.