Visual images preserve metric spatial information: Evidence from studies of image scanning.
Stephen M. Kosslyn, Thomas M. Ball, Brian J. Reiser · Journal of Experimental Psychology Human Perception & Performance · 1978
Four experiments demonstrated that more time is required to scan further distances across visual images, even when the same amount of material falls between the initial focus point and the target.Not only did times systematically increase with distance but subjectively larger images required more time to scan than did subjectively smaller ones.Finally, when subjects were not asked to base all judgments on examination of their images, the distance between an initial focus point and a target did not affect reaction times.Introspections about visual imagery very often include references to "scanning" across images.Kosslyn (1973) attempted to demonstrate that scanning of images is a functional cognitive process, and his experiment indicated that more time was required to traverse greater distances across mental images.However, in the course of scanning longer distances, 1 people in Kosslyn's experiment also passed over more parts of the imaged object.For example, in scanning from the motor to the porthole of an imaged speedboat, a person passed over the rear deck and part of the cabin; in scanning from the motor to the more distant anchor, one scanned over all of these parts plus the front deck and bow.Given this confounding, then, we have no way of knowing whether Kosslyn's results were a consequence of people actually scanning over a quasi-pictorial, spatial image.One could argue that the image itself was epiphenomenal in this situation and that the apparent effects of distance actually were a consequence of how