Psychological review Author:James Mark Baldwin Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: AN EXPERIMENT ON GETTING AN AFTER-IMAGE FROM A MENTAL IMAGE. BY JUNE E. DOWNEY. University of Wyoming. In the literature of the subject one finds a deplo... more »rable lack of detail both as regards methods used and results obtained. Leaving out of consideration the experiments conducted on hypnotized persons, the classic references are to the cases of Fdre and Meyers and to the general statements of Wundt. The great difficulty that suggests itself to even the most casual reader of the passages in question is the one upon which Dr. Franz lays stress in his monograph upon after-images, namely, that the subject, who, in the nature of the case, must be an exceptionally vivid visualizer, could very well suggest a sequence of colors corresponding to after-image effects unless this possibility were ruled out by the subject's absolute ignorance of the very existence of after-images. That the subject should be na'ive as regards after-images is the first and paramount requirement for the success of the experiment. Other requirements and precautions suggest themselves, however. The subject must have his mental images under control; he must be able to hold them for a certain length of time; he must, moreover, be to a certain degree a trained observerâ??that is, able to observe and to report accurately upon color sequences. Usually, in work upon after-images, constancy in result is held to be the test of the trained observer, and yet even under the most unvarying objective conditions variations in the results obtained from any one individual will occur. Naturally one would expect to find this difficulty increased in dealing with mental images where the attributes of quality, intensity and duration could not be kept absolutely constant. Variation in result is usually balanced by frequent repet...« less