In the theatre of consciousness. Global Workspace Theory, a rigorous scientific theory of consciousness
Abstract:Can we make progress exploring consciousness? Or is it forever beyond human reach? In science we never know the ultimate outcome of the journey. We can only take whatever steps our current knowledge affords. This paper explores today's evidence from the viewpoint of Global Workspace (GW) theory. First, we ask what kind of evidence has the most direct bearing on the question. The answer given here is ‘contrastive analysis’ -- a set of paired comparisons between similar conscious and unconscious processes. This body of evidence is already quite large, and constrains any possible theory (Baars, 1983; 1988; 1997). Because it involves both conscious and unconscious events, it deals directly with our own subjective experience, as anyone can tell by trying the demonstrations in this article.
One dramatic contrast is between the vast number of unconscious neural processes happening in any given moment, compared to the very narrow bottleneck of conscious capacity. The narrow limits of consciousness have a compensating advantage: consciousness seems to act as a gateway, creating access to essentially any part of the nervous system. Even single neurons can be controlled by way of conscious feedback. Conscious experience creates access to the mental lexicon, to autobiographical memory, and to voluntary control over automatic action routines. Daniel C. Dennett has suggested that consciousness may itself be viewed as that to which ‘we’ have access. (Dennett, 1978) All these facts may be summed up by saying that consciousness creates global access.
How can we understand the evidence? The best answer today is a ‘global workspace architecture’, first developed by cognitive modelling groups led by Alan Newell and Herbert A. Simon. This mental architecture can be described informally as a working theatre. Working theatres are not just ‘Cartesian’ daydreams -- they do real things, just like real theatres (Dennett & Kinsbourne, 1992; Newell, 1990). They have a marked resemblance to other current accounts (e.g. Damasio, 1989; Gazzaniga, 1993; Shallice, 1988; Velmans, 1996). In the working theatre, focal consciousness acts as a ‘bright spot’ on the stage, directed there by the selective ‘spotlight’ of attention. The bright spot is further surrounded by a ‘fringe,’ of vital but vaguely conscious events (Mangan, 1993). The entire stage of the theatre corresponds to ‘working memory’, the immediate memory system in which we talk to ourselves, visualize places and people, and plan actions.
Information from the bright spot is globally distributed through the theatre, to two classes of complex unconscious processors: those in the darkened theatre ‘audience’ mainly receive information from the bright spot; while ‘behind the scenes’, unconscious contextual systems shape events in the bright spot. One example of such a context is the unconscious philosophical assumptions with which we tend to approach the topic of consciousness. Another is the right parietal map that creates a spatial context for visual scenes (Kinsbourne, 1993). Baars (1983;1988; 1997) has developed these arguments in great detail, and aspects of this framework have now been taken up by others, such as the philosopher David Chalmers (1996). Some brain implications of the theory have been explored. Global Workspace (GW) theory provides the most useful framework to date for our rapidly accumulating body of evidence. It is consistent with our current knowledge, and can be enriched to include other aspects of human experience.