Association for the Scientific Study of Consciousness, 10th Annual Conference (review)

In its recent 125th-anniversary edition, Science magazine listed the top 25 questions still to be resolved by science. The understanding of the biological basis of consciousness was placed second in importance only to the question of what the universe is made of. This explosion of interest in the study of consciousness over recent years is all the more remarkable given that it was seen as a topic barely suitable for scientific investigation just a couple of decades ago. Even now there are some who consign such research to the fringes of scientific acceptability. Nevertheless, it is clear from the 10th Annual Conference of the Association for the Scientific Study of Consciousness (ASSC) that the problem is attracting some of the most advanced investigators and thinkers working today, many of whom presented their latest research to the 300 or so attendees.

Although the conference is primarily scientific in purpose, there were a good number of philosophical contributions. Indeed the proceedings were initiated with a talk from Daniel Dennett, author of Consciousness Explained and recently elected president of the ASSC. In the fitting surroundings of the Natural History Museum in Oxford, he drew an analogy between the gradual evolution of biological species and the emergence of conscious thoughts, arguing that at no specific time or in no specific place can one say that a particular species or thought occurs. Each event, he claimed, is embedded in a wider temporal process that relies on the dynamic organization of sub-events, none of which in itself constitutes the larger property in question. For Dennett, the personal mind is organized from numerous "sub-personal" or "robotic" neurological events, which are distributed in time and space and act collectively to produce conscious experience. This collective activity supports a kind of "fame-in-the-brain" or "cerebral celebrity" for those mental events we are aware of—these being Dennett's metaphors for the general propagation of conscious thoughts throughout our cognitive architecture. It was a philosophical argument, made with reference to certain empirical data but nevertheless pointing to the deep conceptual problems we face in understanding the very thing with which we understand things, namely the mind.

Such introspection, however, was entirely absent from many of the scientific talks, which largely consisted of the presentation of experimental data that tended to measure degrees of "awareness" rather than states of "consciousness." The neuroscientist John Driver, for instance, presented research on cross-modal sensation and its effect on spatial awareness in which he showed that the ability to determine the position of particular tactile stimuli on the body is affected by visual and auditory cues. To give a simple example, it is harder to report which hand is being stimulated when both are placed close together compared to when they are far apart. As Driver demonstrated, much evidence has accrued in recent years to support this cross-modal view of perception, in which each sensory pathway is significantly modulated by other pathways, with the consequence that the conventional notion that we experience the world through distinct senses is no longer tenable. The long-term aim of much research in the field is to discover some neurological basis for conscious experience, the so-called neural correlates of consciousness. Recent interest has focused on the "recurrent processing" that occurs when neural impulses from higher processing areas in the brain are returned to earlier processing centers from which they originated. The presence of this kind of internal feedback in the visual system can be shown to closely correlate with the subject's awareness of a particular event, and both Victor Lamme and Vincent Walsh presented experiments and arguments that supported this view in the first symposium. As was made clear, however, although recurrent processing seems necessary for visual awareness, the question remains open whether it is also sufficient.

Christof Koch, one of the leading figures in consciousness research, picked up the neural-correlate theme in his contribution to the second symposium. Koch is...