Image and Brain: The Resolution of the Imagery Debate

Science - 1995-01-01Georgopoulos AP
Kosslyn's Image and Brain is a tour de force in the analysis of visual perception and imagery, looked upon from all possible perspectives. It is an examination of work done during the past 15 years on visual imagery by a variety of methods, from chronometric measurements to computer models to functional brain imaging, bringing a systematic approach to bear on this multitude of data to delineate the issues of brain mechanisms underlying visual perception and imagery. The scheme adopted posits a number of systems and subsystems (for example for edge detection and for encoding motion relations) that process specific kinds of information and that together make for an apparently seamless operation of visual perception and imagery. This analytical approach is open-ended, in the sense that more processing stations can be adduced if need or evidence for them arises; it is flexible, so that rearrangements in processing order are allowed for; and it is powerful, so that it can be applied rigorously to complex data. The net result is a coherent theory of visual perception and imagery in which results obtained by a diversity of methodologies--observations in normal and braindamaged people, neuroimaging, neurophysiological experiments, and computer modeling--can be accommodated and used to explore and fill in gaps in our account of observed phenomena. This calculus of processes, as it were, that Kosslyn develops can be applied to diverse situations. An excellent example is its application to the case of a particular brain-damaged patient, as detailed on pages 276-282. ...