Reviewed by Peter Tunstall, Chicago

This collection offers a rich, multidisciplinary cross-section of current thinking on the notoriously elusive subject of consciousness, with a particular focus on conscious/non-conscious interactions.

Contributions are distributed among four sections: ‘Neuronal mechanisms’, ‘Psychological processes’, ‘Psychopathologies and therapies’, and ‘Expanding boundaries’. The first deals with brain chemistry and anatomy, connections, and synchronization; topics include gamma oscillations, general anesthesia, and the role of the endocannabinoid system in mediating the unconscious processes that underlie conscious moods. The second contains discussions of memory (implicit and explicit), social consciousness, lucid dreaming, and what magicians can teach us about attention and visual awareness. The third includes chapters on depression, dementia, schizophrenia, 3,4-methylenedioxy-N-methylamphetamine (MDMA) use, and the placebo effect, and the final part explores creativity, psi phenomena, and self-induced altered states of consciousness, such as those induced by meditation and the use of entheogens. The emphasis is toward the empirical rather than the philosophical strand of consciousness studies.

Two chapters deal explicitly with linguistic issues. In ‘Consciousness and language: A processing perspective’, Michael Sharwood Smith and John Truscott propose that ‘some linguistic processes are inherently unconscious while others can be conscious or not’ (129). Drawing on Bernard J. Baars’s global workspace model of consciousness and Ray Jackendoff’s intermediate-level theory, they contrast functions of the language module itself, which never reach activation levels sufficient for consciousness, with on extramodular linguistic knowledge, which includes conceptual representations (unconscious) and perceptual representations (conscious): ‘processing within the language module is entirely unconscious but nevertheless relies on conscious perceptual processes to provide its input and leaves conscious footprints in the form of the voice in the head’ (135). While much of this is plausible, one may question whether linguistic consciousness is wholly accounted for as a ‘set of perceptual blackboards, each representing the ultimate output of a sensory system’ (133). There is more to conscious thought than subvocalization.

In ‘Consciousness as the spin-off and schizophrenia as the price of language’, Timothy J. Crow attributes schizophrenia to developmental defects associated with hemispheric asymmetry. These defects, he proposes, lead to a kind of ‘aberrant transmission (backflow)’ (193) between the four quadrants of the cortex, resulting in pathologies of language and self-awareness. While the link between schizophrenia and lateralization abnormalities is supported by post-mortem studies (194), it seems something of a leap to identify the right hemisphere as the seat of reflexive consciousness. Because pre-psychotic children show language impairments (195), and schizophrenia is seen as an ‘illness of the self’ (197, quoting Maxim I. Stamenov), he concludes that language is crucial to a sense of self: ‘the components of language fall apart, and consciousness fragments’ (197). Some acknowledgement of non-psychotic aphasias would be in order here; how are we to account for the apparent persistence of self-awareness in these cases?

It is impossible to do justice in so small a space to the range of topics covered here and to the inventiveness of ideas displayed. While this book offers neither consensus nor closure on the nature of consciousness, it provides much food for thought.