Case for Mental Imagery

Mental imagery has always been a controversial topic in psychology. The major problem has been the inherently private nature of mental images, which has traditionally prevented objective assessment of their structure and function. Between researchers in cognitive psychology and computer-science, a debate, now commonly called 'the imagery debate' arose about what exactly constitutes a mental image. Although the imagery researchers in cognitive psychology assumed that mental images were in fact images, and hence often compared them to pictures, the computer-science researchers relied on language-like internal representations that are easy to implement in programming languages. On the side of the computer-science researchers, Zenon Pylyshyn has argued that the picture metaphor underlying theoretical discussions of visual mental imagery is seriously misleading, particularly because it suggests that an image is an entity to be perceived. Pylyshyn has claimed that to describe what we know adequately, we must posit mental structures that describe, that are conceptual and propositional in nature, rather than sensory or pictorial-symbolic descriptions, rather than images. On the side of the mental-imagery researchers, Stephen Kosslyn has argued that the idea that mental depict, as opposed to describe, is not only defensible, but most consistent with the emerging body of data about imagery. In this volume, Stephen Kosslyn revisits the debate some 30 years later, when it has evolved to bear on a much more general concern: the relation between mental phenomena and underlying natural substrates. Kosslyn summarises the arguments and positions, puts them in context, and shows how modern neuroscientific methods can illustrate the representational nature of mental imagery.

Stephen M. Kosslyn is the former Chair of the Department of Psychology, currently Dean of Social Science and John Lindsley Professor of Psychology at Harvard University. His research focuses primarily on the nature of visual mental imagery, visual perception, and visual communication; he has published 5 previous books and over 275 papers on these topics. Kosslyn has received numerous awards, including the National Academy of Sciences Initiatives in Research Award, a Guggenheim Fellowship, and election to the American Academy of Arts and Sciences. William L. Thompson received his BA in psychology from McGill University in 1990 and since then has worked in Stephen Kosslyn's laboratory in the Psychology Department at Harvard University. Using the techniques of positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), he has worked on numerous neuroimaging studies, investigating primarily visual mental imagery, but also color perception, hypnosis, and mental rotation. He has co-authored over 30 journal articles and book chapters, including extensive reviews and meta-analyses of the visual mental imagery literature. Giorgio Ganis has a Ph.D. in Cognitive Science from the University of California at San Diego. He is Assistant Professor in Radiology at the Harvard Medical School and Research Associate in psychology at Harvard University. His research has focused primarily on the neural correlates of visual cognition in humans, and he has published numerous scientific papers on this topic. Ganis has received various awards, including a McDonnell-Pew Program in Cognitive Neuroscience Grant.