OPEN QUESTIONS ON SHANAHAN'S WORKSPACE

Murray Shanahan [2010] has written a nice book about the neural underpinnings of the conscious condition. He begins with some philosophical background remarks (Chap. 1) and proceeds then to the issues of cognition and embodiment and nally to his model of consciousness, which is inspired by the Baars' global workspace model [Baars, 1997]. The objective of this book is obviously the phenomenon of consciousness, but Shanahan wisely limits his pursuit and attempts to explain the conscious/unconscious distinction. The Baars global workspace model is based on earlier black board models used in Arti cial Intelligence. In these models, the black board is a working memory containing the task at hand. A number of autonomous experts read the black board and compete for permission to write on it. At each moment, the access is granted to the expert that has the most relevant piece of information to o®er. According to Baars, the brain can be thought as a system of a number of autonomous expert modules and a global workspace. The global workspace is a working memory, which contains the contents of consciousness. Baars states that the global workspace is a kind of a theater stage, where inner speech and inner imagery take place in a serial way. Thus, the global workspace model is a theater model. Baars proposes that in the brain, the global workspace is located at the sensory projection areas of the cortex. According to Baars, the expert module processes are unconscious and the global workspace process is conscious. Shanahan's view about the global workspace is di®erent. Firstly, he wishes to distance himself from the theater model by recasting the role of the global workspace. Instead of a working memory, the global workspace should be thought as a communications infrastructure that connects the various autonomous units with each other: \Indeed, unless recast this way, the putative workspace might be mistaken for a dedicated brain region, something akin to the Cartesian theater ridiculed by Dennett." Shanahan proposes that in the brain, the global workspace consists of the International Journal of Machine Consciousness Vol. 3, No. 2 (2011) 339 341 #.c World Scienti c Publishing Company DOI: 10.1142/S179384301100073X