Optic flow provides all the information necessary to guide a walking human or a mobile robot to its target. Over the past 50 years, a body of research on optic flow spanning the disciplines of neurophysiology, psychophysics, experimental psychology, brain imaging and computational modelling has accumulated. Today, when we survey the field, we find independent lines of research have now converged and many arguments have been resolved; simultaneously the underpinning assumptions of flow theory are being questioned and alternative accounts of the visual guidance of locomotion proposed. At this critical juncture, this volume offers a timely review of what has been learnt and pointers to where the field is going.

This volume is not an attempt to give a comprehensive treatment of the many facets of intelligence. Rather, the intention is to present multiple approaches to interesting and novel ways of looking at old problems. The focus is on the visual and some of the conceptual intelligences. Vision is man's primary cognitive contact with the world around him, and we are vividly reminded of this by Roman Jakobson's autobiographical note, "The Evasive Initial" with which this volume begins. That we see the world as well as we do is something of a miracle. Looking out through our eyes, our brains give us reliable knowledge about the world around us in all it beauty of form, color and movement. The chapters in the first section look at how this may come about from various perspectives. How from the intensity array which the world casts on the eye's retina does the brain achieve recognition? What may be some of the processes involved in seeing? We see shapes, textures and colors, and subsequently, at the more cognitive levels, recognize them as objects which we can manipulate: we inspect them to discover what to use them for. The objects are tools or food; they are things, beautiful, lovable or frightening. They are things to remember and to talk about to our friends, or to ask someone for. We can ask for many or just a few. They are important to us or trivial.

Optic flow provides all the information necessary to guide a walking human or a mobile robot to its target. Over the past 50 years, a body of research on optic flow spanning the disciplines of neurophysiology, psychophysics, experimental psychology, brain imaging and computational modelling has accumulated. Today, when we survey the field, we find independent lines of research have now converged and many arguments have been resolved; simultaneously the underpinning assumptions of flow theory are being questioned and alternative accounts of the visual guidance of locomotion proposed. At this critical juncture, this volume offers a timely review of what has been learnt and pointers to where the field is going.

Communication is one of the most challenging human phenomena, and the same is true of its paradigmatic verbal realization as a dialogue. Not only is communication crucial for virtually all interpersonal relations; dialogue is often seen as offering us also a paradigm for important intra-individual processes. The best known example is undoubtedly the idea of concep tualizing thinking as an internal dialogue, "inward dialogue carried on by the mind within itself without spoken sound," as Plato called it in the Sophist. At first, the study of communication seems to be too vaguely defmed to have much promise. It is up to us, so to speak, to decide what to say and how to say it. However, on eloser scrutiny, the process of communication is seen to be subject to various subtle constraints. They are due inter alia to the nature of the parties of the communicative act, and most importantly, to the properties of the language or other method of representation presupposed in that particuIar act of communication. It is therefore not surprising that in the study of communication as a cognitive process the critical issues revolve around the nature of the representations and the nature of the computations that create, maintain and interpret these representations. The term "repre sentation" as used here indicates a particular way of specifying information about a given subject."