One of the best ways we have to figure out how the mind is structured at the level of mechanism is to examine cases in which it functions in abnormal ways. The basic idea is that those mechanisms exhibit specific patterns of breakdown that are informative about their structure and functional composition. Here’s a basic example. In the study of language – one of the earliest examples of this methodology in action – it was found that specific patterns of brain damage would cause different kinds of aphasia, and this was helpful in surmising the contribution that different parts of the brain make to language-production. So, for instance, damage to Wernicke’s area would cause an aphasia in which a person had no problem speaking but the content of that speech would be largely meaningless; damage to Broca’s area would cause an aphasia in which the person could not produce speech at all, or only with great difficulty, but in which the words produced would be semantically appropriate. This informs theorisation about language-production in a number of ways: it tells us how the overall capacity is decomposed into simpler functions, at least, and it teaches us something about the physiological structures which are necessary to the performance of those functions.

          It seems that this strategy might be applied to elucidate some of the other capacities which make up human mentality. That is the overall theme of this book, which is focused upon the capacity that human beings have for consciousness. It is premised, that is, on the idea that psychopathological conditions which include abnormal or disordered states of consciousness can help us theorise more generally about the structure and functional composition of consciousness. These conditions have received their fair share of scientific attention, but perhaps not so much in light of the debate over the theorisation of consciousness. They include the depersonalisation disorders, somatoparaphrenia, schizophrenia, split consciousness following brain bisection, and others, and any adequate theory of consciousness must be able to account for these. Careful examination of those conditions might therefore be a helpful constraint on the debate over consciousness, or at least that is the central premise of this book. In this review I will discuss the different debates that run their way through the book, rather than giving an itemised description of every single contribution.

          Here’s an example that looms large in the first four chapters. Very briefly, it has been claimed by Liang and Lane (2009) that somatoparaphrenia – a delusion wherein the patient denies ownership of a limb or other body part – demonstrates that the higher-order representation or HOR theory of consciousness cannot be true. The HOR theory states that a mental state is conscious in virtue of it the subject being aware of it as one’s own, and that this is realised by the state being the object of a higher order representation. But in somatoparaphrenia the patient is both conscious of the limb and not aware of it as his own (in some cases ownership of the limb is even attributed to another person). So this “subjectivity” condition on consciousness, and a fortiori HOR itself, must be false.

          This is not the only condition in which subjectivity and consciousness seem to dissociate; Billon and Kriegel show in the first chapter that depersonalisation disorders exhibit a similar dissociation, and in a way that is harder for HOR theorists to account for. But on their view, there are two possible ways in which one can respond to such challenges. Either claim that these cases exhibit both subjectivity and consciousness, but lack subjectivity* or consciousness* (which are nearby but distinct concepts, such as “sense of agency”), or that these cases exhibit both subjectivity and consciousness and also some further positive phenomenon which makes the case pathological (like, for example, a phenomenology of alienation) rather than a deficit in either subjectivity or consciousness. I found that this mapped out the possibilities in this debate quite nicely. Varieties of either approach are taken by Gennaro and Mylopoulos in the next two chapters, and Lane gives a lengthy response in a chapter of his own.

          The subjectivity condition on consciousness – that a state is conscious in virtue of the sense of “mine-ness” on the part of whoever is enjoying that conscious state – is also challenged later on in the book, in the contribution by O’Brien and Opie. They cite both neurological and behavioural features of schizophrenia that they think motivate away from these “process” theories of consciousness and towards their own “vehicle” theory of consciousness. This distinction of theirs seems to me to mirror the more widely used first-order/higher-order distinction, and a vehicle theory of consciousness entails that a state is conscious just in virtue of its representational properties. Theories of this kind are unpopular, since cognitive psychology appears to tell us that there are many representational states that are nonetheless non-conscious (the representation of light-dark contrast at early stages of visual processing, for example). But O’Brien and Opie can account for this fact by saying that they espouse connectionism rather than classical cognitivism, and that on connectionism there are multiple modes of representation. Only one of these modes gives rise to consciousness.

            There are a few features of schizophrenia that apparently motivate for a vehicle, rather than a process, theory. The most salient of these are the reduced activity in the prefrontal cortex, which we should not expect on a process approach like HOR. That is because schizophrenics experience both a deficit in frontal cortex activity along with an amplification of consciousness in various ways, and O’Brien and Opie think that process theorists are committed to saying that the prefrontal cortex is implicated in the higher-order process or representation which makes for a conscious state. The vehicle theory, by contrast, makes the neurobiology of schizophrenia consistent with its phenomenology. Hirstein makes a similar point in his contribution on network underconnectivity in autism; cases like these motivate against the view that sophisticated higher order processes or functions are necessary to consciousness. There are therefore some deeper themes raised by these latter two chapters that touch upon the distinction between cognitive and non-cognitive theories of consciousness (cf., Block 2011).

          Here is another question about consciousness that might be answered with the aid of psychopathology, and which is discussed by some of the contributors: is consciousness always unified? Brooks and Van Gulick argue in separate chapters against unity as a necessary feature of consciousness – a controversial thesis, given the endorsement of the unity condition in classical and recent literatures (cf., Bayne 2010). In doing so they appeal to dissociative identity disorder and brain bisection, and dispute interpretations of those illnesses that have been given in order to preserve the unity condition on consciousness (e.g., Bayne’s hypothesis that the unified conscious field switches between two streams of representational information in brain bisection cases). More specifically, and in reference to Brooks’ contribution, it is argued that the link of unified consciousness to autobiographical memory demonstrates that consciousness does not “switch” in the case of brain bisection – if it did, then we should expect there to be some break in the patient’s sense of self to occur during any such “switch,” since consciousness would gain access to episodic autobiographical memories that were laid down in the other stream, and to which the subdominant stream had no access.

          Also worthwhile looking at in this collection is Hohwy’s essay, in which he considers psychopathology and consciousness under the umbrella of the prediction error minimization framework – a large-scale theory of perception, cognition and action that has recently been gaining momentum in cognitive neuroscience. In this framework, phenomena as diverse as schizophrenia, autism, and various perceptual illusions can be given compelling mechanistic explanations, and in a way which shows them all to be dysfunctions of a single overarching mechanism. Perhaps then, and especially given the disorders of consciousness in some of these phenomena, we might expect prediction error minimization to yield clues as to how the characteristics of conscious experience arise and how they may deviate from the norm in psychopathology. Howhy follows up on this intuition by connecting the mechanism of prediction error minimization to a synthesis of Lau’s (2008) Bayesian meta-cognitive theory of consciousness and the ever-popular global workspace theory. This essay will be of special interest to those following the general discussion about predictive processing as well as the themes which are central to this book itself.

          There are also some interesting chapters which take self-deception as their focus – more specifically, disorders of belief formation (like delusion) that appear to have self-deception as a possible causal contributor. Droege, for instance, offers a take on confabulation that brings together elements from Darwinian approaches to mind and representation in order to give what she claims to be a mechanistic underpinning to the psychodynamic trope of consciousness negotiating incompatible demands between instinctual and socio-cultural imperatives. Likewise, Pliushsch and Metzinger give a model which is meant to account for such phenomena, though theirs is more deflationary when it comes to self-deception and its link to motivation. In any case, these essays are interesting in the way that they link the consciousness literature to conceptual work on self-deception and its link (or lack thereof, in the case of the latter chapter) to mental partition (e.g., Mele 2001).

          In sum, this is an interesting and well thought out collection that has the effect of bringing together much of the previous literature on a number of diverse but nearby topics. If I had any complaint, it would be that there is a lack of unity with respect to the essays. The essay by Myin et al., which deals with the way that consciousness and psychopathology could be alternatively explained within a strong “4E” framework, is somewhat out of step with the larger debates which are taken up in the book, and the same could be said of Hohwy’s contribution as well. (Both of these essays are nonetheless very good.) However, this is partly a consequence of the state of the field itself, and therefore not a great fault on the part of the editor. The book should be considered essential for philosophers of mind who are interested in new research on consciousness, or psychopathology, but especially for those who are interested in both.

 

References

Bayne, T. (2010). The Unity of Consciousness. Oxford: Oxford University Press.

Block, N. (2011). Perceptual consciousness overflows cognitive access. Trends in Cognitive Sciences, 15, 567-575.

Lau, H. (2008). A higher order Bayesian decision theory of consciousness. Progress in Brain Research, 168, 35-48.

Liang, C., & Lane, T. (2009). Higher-order thought and pathological self: The case of somatoparaphrenia. Analysis, 69, 661-668.

Mele, A. (2001). Self-Deception Unmasked. Princeton: Princeton University Press.

 

© 2016 Andrew Sims

 

Dr. Andrew Sims, Casual Academic, Philosophy, School of Humanities and Social Sciences, Deakin University