A question often on the minds of Cognitive Neuroscientists these days concerns the relation between perception and action. Those who are outside the field of perception may be excused for thinking that this must have always been so. What is perception for if not to inform the organism about the external world, so as to best guide its actions in the service of survival? Well, it is not much of an exaggeration to say that, with the exception of a few persistent "cranks" (e.g., James Gibson, Ulrich Neisser), most of what has passed for perception research in the past century has blithely ignored the interplay between perception and action. Most perception researchers were quite content to allow action to be studied by those in the related, but largely self-contained, specialities of human movement, motor performance, and kinetics. What perception researchers studied was the way the world appeared to someone sitting in an armchair, contemplating the information available in the visual array at their leisure.
Something distinctly Canadian' changed all that in 1995, with the publication of a book by David Milner (St. Andrews, Scotland) and Mel Goodale (University of Western Ontario, Canada) entitled The Visual Brain in Action. That book laid out a theory and a research program that was at the same time elegant in its simplicity, broad in its scope, and revolutionary in its impact. The elegance lay in the clear presentation of yet another dichotomy (of which psychologists are so fond), this time between the visual maps that lie in the dorsal versus ventral regions of the cortex. What made this dichotomy so compelling was that it encompassed and gave organization to a number of earlier and smaller-scale dichotomies, including that of action-perception, unconscious-conscious, preattentive-attentive, bottom up-top down, and what-where. The breadth of its scope could be seen in the way the book moved effortlessly from simple animal models of perception, to human neuropsychological conditions, to the analysis of behaviour and brain imaging in psychology's favourite "normal" research participant, the college undergraduate. The impact of the book can now be seen everywhere, but especially at annual conferences in psychology, vision research, neuropsychology, and brain imaging, where the modal presentation begins with a slide depicting the proposed division of labour between dorsal and ventral visual streams.
The four papers in this volume representing Canadian work in Perception and Action each have strong threads linking directly to the Milner and Goodale legacy. This section begins with a paper by Flanagan, King, Wolpert, and Johansson examining the role of long-term memories in participants' adaptation to a size-weight illusion. A guiding theoretical question in this work is whether sensory information is quickly lost or overwritten when it is used for action, as Milner and Goodale contend. …