Book Review: In Consciousness We Trust by Hakwan Lau

There was a time when psychologists focussed mostly on experiments and piecemeal progresses, leaving big pictures and theoretical adventures to philosophers. That time has ended, as we see substantive theoretical frameworks coming out of experimentalists’ minds: along with Being You (Seth, 2021) and Know Thyself (Fleming, 2021), In Consciousness We Trust is yet another contribution in the same vein. The book epitomizes Hakwan Lau's research program in cognitive psychology and neuroscience in the past two decades, which deals with thorny theoretical issues concerning the nature of conscious experiences. It touches on the empirical literature on conscious perception, attention, metacognition, rational control, emotion, and the sense of agency, among others. But the book does not simply review findings; it also presents an empirically informed original theory of consciousness. Lau's narrative is alive and includes personal journeys, which make the book very readable and intriguing.

The book has an introduction and nine chapters, and usefully contains succinct yet informative summaries of chapters. Introduction explains why the right level for understanding consciousness is cognitive neuroscience rather than physics (contra, e.g., Sir Roger Penrose) via discussing some aspects of the recent history of consciousness studies. Ch.1 discusses the relations between subjective experience, wakefulness, and voluntary control. It also introduces the key contrast between global (e.g., Baars, 1989; Dehaene, 2014; Dennett, 1991) and local theories (e.g., Lamme, 2003, 2006; Zeki, 2001), and five key issues that help arbitrate between the global and the local. Ch.2 argues that the relevant evidence favors the view that the prefrontal cortex is part of the neural correlate of consciousness. It also discusses the nature of NCC, blindsight, stimulus confounder, binocular rivalry, and no-cognition paradigms. Ch.3 points out that the relevant lesions and stimulation studies, barring certain conceptual confusions, further support the prefrontal involvement of consciousness. Ch.4 discusses the relation between attention and the apparent richness of consciousness, and how it creates problems for local theories; it also discusses a traditional puzzle “speckled hen” in philosophy, the classical partial report paradigm in psychology by Sperling (1960), load theory of attention, peripheral vision, and so on. Ch.5 discusses potential functions of consciousness and covers issues such as subliminal priming, Libet's classical experiment on volition and free will, and metacognition. The result here puts pressure on global theories. Ch.6 argues that neither global nor local theories seem right given what has been discussed so far, so the author's alternative—the centralist proposal—looms large (other centralists include, e.g., Cleeremans et al., 2020). It also discusses issues such as predictive coding, constraints of a plausible theory of consciousness, and how recent progresses in artificial intelligence can shed lights in this regard. Ch.7 discusses the perceptual reality theory, which predicts that some nonhuman animals are unconscious, while some artificial systems could be conscious; it also discusses optimal Bayesians, phantom pains, higher-order thoughts versus beliefs, inner sense, and many other issues. Ch.8 relates “consciousness” as understood in the current context and “consciousness” in the context of the social and clinical sciences, that is, rational grasp of reality; it does this by discussing split-brain cases, schizophrenia, affective experiences, among other things. Ch.9 dives into the heart of consciousness studies—the hard problem—and argues that cognitive-neuroscientific theories do better than so-called “metaphysical theories”; it also touches on important notions such as quality space and analog representations. This summary does not do justice to how rich the book is, but we shall save some space for discussions below. One thing to be noted is that although the book has covered much ground, it seems to leave out some questions that readers might wish to know. For example, what roles do the structures of temporal lobes, for example, parahippocampal place area (PPA), fusiform face area (FFA), and lateral occipital complex (LOC), play in generating consciousness? Do they provide contents only (e.g., faces), regardless of whether the contents are conscious?

Here, we will focus on two conceptual issues, which can seem merely terminological but are actually substantive. The first one concerns the term “raw feel” and its relations to other similar terms. By “raw feel,” the author means “something it is like,” and he takes it to be synonymous as “subjective experience,” “conscious experience,” “qualitative experience,” “subjective feel,” “phenomenology,” “phenomenality,” “phenomenal quality,” “phenomenal experience,” “phenomenal consciousness,” and “conscious awareness.” Now, these are theoretical terms that are up for grabs, so readers should accept the author's stipulations. However, using “raw feels” to denote consciousness is actually inapt for the author's purposes, given that his view of consciousness has an intellectualist flavor which implies that sophisticated mental processes are involved in consciousness. This is not a criticism of the view; it is just a suggestion that given his overall outlook, consciousness is nothing “raw”; instead it is “cooked,” for example, by higher-order states or prefrontal processes. If anything, “raw feels” are more suitable for those who believe in the Overflow thesis, such as Ned Block (2007, 2018). Things get worse when the author equates those terms, as many of them are of different ontological categories. For example, while phenomenality and phenomenal quality are properties, conscious experience and qualitative experience are episodes. This is significant for the author's project because he intends to have philosophers, who are extra sensitive to subtle meanings, as his audience too.

Next, and more importantly, is that the author's criticisms against panpsychism, even if cogent, are misplaced. To put it bluntly, while the author's mainline here concerns NCC, panpsychism should not be construed as an answer to the NCC question. Here, we need to distinguish two projects of explaining consciousness; one is horizontal in the sense that it sticks to correlates only, and asks (for example) whether the prefrontal cortex is involved in the correlates. The other is vertical in the sense that it takes a stand on the nature of the correlations: is it identity, reduction, causation, supervenience, constitution, emergence, or grounding? Panpsychism, being a metaphysical theory, deals with this vertical question. I share the author's sentiment against panpsychism, but I suggest that in evaluating it we need to be clear that it is not supposed to engage the horizontal NCC project.

No matter how convincing one finds the book is, this is a must-read for everyone in consciousness research, and this is one of the best books in this area in the 21^st century so far. It is also of particular interest for Perception readers, as many key examples in the book—such as blindsight, binocular rivalry, speckled hen, the partial report paradigm, and peripheral vision—are all instances of perceptual consciousness. Although the author's theory is a general one concerning consciousness, many of his ideas are distilled from cases of perception. Finally, a bonus is that this is an open-access title, which gives one more reason why you should read it too.