Foreword

The enigma of how consciousness rises from biological phenomena has perplexed scientists, leading some of the greatest minds, including Nobel Laureates Leon Cooper, Francis Crick, Gerald Edelman, Eric Kandel, and Charles Sherrington, to conclude that answering this question is one of the greatest challenges in science. As Shallice [1] concludes, “The problem of consciousness occupies an analogous position for cognitive psychology as the problem of language behavior does for behaviorism, namely, an unsolved anomaly within the domain of the approach”.

Similarly, Chalmers [2] states, “We know consciousness far more intimately than we know the rest of the world, but we understand the rest of the world far better than we understand consciousness”. The puzzle of “consciousness-and-the-brain,” or of the “mind-body” problem, is often ranked as one of the top two unanswered scientific questions [3].

When speaking about consciousness, we are referring to its most basic form, the kind falling under the rubrics of ‘subjective experience,’ ‘qualia,’ ‘sentience,’ ‘basic awareness,’ and ‘phenomenal state.’ This basic form of consciousness has been best defined by Nagel [4], who claimed that an organism has basic consciousness if there is something it is like to be that organism—something it is like, for example, to be human and experience pain, love, or breathlessness. Similarly, Block [5] claimed, “the phenomenally conscious aspect of a state is what it is like to be in that state”.

The scientific challenge concerning consciousness is far more daunting than what non-experts may surmise: investigators focusing on the problem are not only incapable of having an inkling regarding how something like consciousness could arise from something like the brain, they cannot even begin to fathom how something like consciousness could emerge from any set of real or even hypothetical circumstances. That is, if a neuroscientist were provided with all the materials and dimensions (all eleven of them) of the known universe, he or she would still be unable to have an inkling regarding how to go about having basic consciousness arise from anything physical.

In everyday life, being conscious usually just means “being alive.” From the standpoint of this lay intuition, consciousness comes “for free” if one happens to be a living organism: one is alive and, because of this, one is aware of one’s surroundings, bodily states, thoughts, and so on. In truth, however, consciousness is actually an achievement of nervous function. To date, we do not have a single clue regarding how consciousness is achieved.

How can something unconscious be turned into something conscious, that is, to something for which there is something it is like to be that thing? More specifically, what must we do to a set of unconscious neurons to turn them into something that generates a basic conscious state? We will here pose a straightforward question that I think reveals the gravity of the problem: What would one have to do to cause an (unconscious) machine, such as a robot, to experience, say, a dream? This would require more than just the capacity to detect and respond to external stimuli. The challenge is so daunting that any small glimpse of a new clue regarding how it could be solved is priceless.

In this stimulating treatise, Paulo Negro provides thoughtful insights regarding clues and potential answers to the problem of consciousness-and-the-brain. Through the process, he provides an alternative to currently prevalent approaches, such as Integrated Information Theory, Global Neuronal Workspace Theory, Adaptive Resonance Theory, Orchestrated Objective Reduction, and panpsychism (in which consciousness is a property of all matter), each of which is reviewed thoughtfully in the treatise.

Negro’s theory emphasizes action and “the subject and its agency,” which, according to Negro predicates any form of conscious experience (e.g., conscious experience of qualities). Negro states, “There can be no consciousness without a subject because consciousness is the phenomenology of a world presented to a subject.” Unlike prevalent approaches to the study of consciousness, which focus on perception, Negro’s account focuses on action: The “generative model of consciousness has a basis on actions”. Negro concludes, “Consciousness provides a device to dynamically process and extract evolutionarily useful information from reality, for stepwise adaptive behaviors. Consciousness is how evolution feels”.

As noted by Paulo Negro throughout the book, when one embarks on a journey to study consciousness scientifically, one encounters many challenges. Below we delineate just some of these challenges, problems which are addressed throughout this tome.

The natural scientist must explain the difference between conscious processes in the brain and unconscious processes in the brain, of which there are many. Using a descriptive approach, the scientist attempts to explain the products of evolution as they are and not as we would have designed them or as they should be (which would be a normative approach). (Similar to Negro's account, a descriptive approach focuses on phylogeny). As Negro concludes, “Natural history is not the search for an abstract theory, but the understanding of the history of life in our planet”

To the detriment of the scientists, this difference cannot be dismissed and must be explained, one way or another. An explanation is required of science even if one proposes that all matter possesses consciousness (a form of panpsychism), for one must explain how unconscious processes could exist in a panpsychist reality. An explanation is required even if one proposes that consciousness serves no role in the nervous system (a form of epiphenomenalism). Biological phenomena must be explained and incorporated with the theoretical framework for understanding the rest of the natural work, whether they are deemed to be “useful” or not.

Thus, a complete theory of the natural world must explain the difference between conscious and unconscious processes, a difference that exists in every subfield of psychology and of neuroscience. In perception research, there is the distinction between supraliminal versus subliminal processes. In the study of attention, the term ‘attentional awareness’ is often contrasted with unconscious, ‘pre-attentive’ processing [6]. In memory research, there is the classic distinction between ‘declarative’ (explicit) processes and ‘procedural’ (implicit) processes [7-8]. In research on language production and motor control, the conscious aspects of voluntary action and action monitoring are contrasted with the unconscious aspects of motor programming [9-10], including the implicit learning of motor sequences [11]. Last, various fields contrast ‘controlled’ processing, which tends to be associated with consciousness, and ‘automatic’ processing, which tends to be associated with unconscious mechanisms [12]. In short, the difference between conscious and unconscious nervous processes is inevitable and must be explained, even if one adopts the stances of panpsychism or epiphenomenalism.

As noted by several theorists, basic conscious contents (e.g., the color blue, urges, or the smell of lavender) are “unanalyzable,” with their qualities being irreducible. Lashley (1923) [13], regarding traditional versions of subjectivism, states:

Thus, the conscious contents of blue, red, a smell, or the urge to blink are the tokens of a mysterious language understood, not by consciousness itself, as is clear in Lashley’s conclusion, and not by the physical world. Instead, they seem to be comprehensible by brain systems whose operations are cognitively impenetrable to us. We experience these conscious contents, and they affect behavior and our decision making, but we simply do not know what they are in the sense that we know what other things are (e.g., heat). We also know that they do not exist as such in the physical, “mental-less” world.

Similarly, our basic sense of a first-person perspective or of time is also a creation, creation with no analogs in the world of physical reality [14]. (Regarding the former, most conscious contents appear as if from a first-person perspective [15-17], be it during waking or dreaming. It has been proposed [15-16,18] that the demands of adaptive action selection, in which action targets can be, say, to the right or left of one, require the creation of this first-person perspective, which is a primitive form of ‘self’). Regarding the first-person perspective, Negro states, “Predictive Coding supports a subject-centric view in which actions are not only the source of consciousness, but also the building elements of the subject itself. The neural correlates of consciousness are what the subject is doing”.

Conscious states such as nausea, the auditory perception of pitch, the urge to sneeze, or the color white [19] simply do not exist in the physical world, just as the symbols displayed in navigational system of a modern car do not exist as such in the physical world. These navigational systems depict restaurants and gas stations as fictional, simplified icons (e.g., large forks and gas pumps, respectively). Though fictional, they influence the driver’s decisions and actions. Based on this example, one can appreciate that our experience of time, space, nausea, and qualities such as colors are not givens of physical reality, or of being alive, but achievements of devoted and specialized neural activities. These achievements are constructions that, unlike their counterparts in the world of physics, can be manipulated experimentally. Consistent with this view, regarding time, Negro states, “Local networks affect qualia of time experienced both in visual and auditory experiments”.

To the self, the conscious field seems “all encompassing”—complete even when conscious contents are obviously absent, as in the cases of sensory neglect (with anosognosia) and in the phenomenon of change blindness [20]. This “completeness” property is evident also in the dream world, in which circumstances are often irrational and fragmented, but not detected as so. As Paulo Negro concludes, “conscious experiences can be seen as running models (expectations) simulating reality” which, to the subject, is the only reality.

This property of completeness stems in part from the fact that one cannot be aware of that which one is unaware of [21]. To illustrate this point, Jaynes [21] uses the example of the blind spot in vision. One is usually unaware of the blind spot, simply because—again—one cannot be aware of that which one is unaware of. More generally, if a conscious content is not in the field, then it cannot influence volitional decision-making and action in any way [18]. For example, if the knowledge representations necessary for, say, ‘reality monitoring,’ are not in the field (e.g., due to high fever), then nothing else can assume the functional influence of these contents. In short, when the appropriate contents are absent, there is no independent repository of knowledge that can supplant these contents [18]. Thus, in the conscious field, there is often the absence of information but seldom information about absence [20,22]. Consciousness is always the totality of one’s experience at one moment in time.

Thus, when the nervous system is functioning normally, the contents of the conscious field at each moment seem not only complete, in the sense described above, but they also seem unambiguous. Merker [23] concludes that, because of the very nature of the constitution of the mechanisms giving rise to conscious sensory representations, the conscious field is actually incapable of representing stimulus ambiguity (e.g., as in the Necker cube), at least at one moment in time.

In order for action to be adaptive, it must be context-sensitive and must allow for what the Behaviorists called a conditional discrimination, in which the response to one stimulus depends on the nature of other stimuli in the stimulus scene. Hence, the consciously experienced meaning of a conscious content in the field, and how one responds to it, depends not only on the semantic representation associated with that conscious content, but also on the relationship between this semantic representation and the semantic representations of the other conscious contents participating in the field at that moment in time [24]. (The critical relationships among stimuli could also be spatial in nature, as in the case in which the adaptive response to Stimulus A depends on the spatial distance between, say, Stimulus B and Stimulus C, with these two stimuli being just two out of many stimuli composing the conscious field). Just as in color perception the nature of the phenomenal experience of one hue is determined in part by the nature of the other hues composing the stimulus scene, a conscious content is framed by the nature of the other conscious contents composing the stimulus scene at that time.

We should add that our intuitions regarding how nervous systems should solve this problem of contextual sensitivity, in which sensory inputs are connected to motor outputs, are actually computationally impossible [25-26]. The conscious field seems to be solving this problem of contextual sensitivity in a manner that is counterintuitive and different from the manner in which we humans would attempt to engineer a solution to the problem of contextual sensitivity.

It turns out that our intuitions regarding how a nonconscious creature might solve the problem of contextual sensitivity in the perception-and-action cycle are actually computationally impossible. That is, just as a computer cannot solve the traveling salesperson problem, many of the problems humans solve in the perception-to-action cycle are known, a priori, to be unsolvable through formal computational means. These problems cannot be solved through computer logic, regardless of how much computational power a computer has.

Nature is doing things differently in its peculiar and often happenstance ways. Reverse engineering the brain and consciousness might reveal clues, not only about what we are, but regarding how to deal with the limitations of our computer and robotic systems, just as the study of the dragonfly, the most sophisticated flyer within and outside the animal kingdom, has led to improvements in aerospace engineering.

Because of their deterministic design, traditional computers are also incapable of generating a truly random event, and hence cannot produce random numbers. Computerized slot machines, for example, are not truly random in nature. But other physical systems, such as those at the quantal level, are truly random in nature [27]. With this in mind, engineers can have slot-machines procure random numbers by having their computers refer to a random event (e.g., a decaying radioactive diode). In this case, a computational goal is achieved by having two different kinds of systems interacting with each other, each system benefiting from the physical properties of the other [28].

Likewise, from a descriptive approach to nervous function, one assumption is that the computational goals that humans confront require, given the hardware at hand, at least two kinds of physical processing—one conscious and one unconscious. Until robotic systems can solve the problem of contextual sensitivity (which seems to be computationally impossible), these systems must interact with humans to function adaptively in the natural world, because humans possess a property (a conscious field) that seems capable of somehow solving this challenge of contextual sensitivity.

Thus, in response to the common criticism “but one can imagine that function without consciousness,” a scientist today can argue that, first, evolution might not have carried out that function the same way that humans imagine it should be engineered, and, second, that our human ideas regarding how such functions could be carried out nonconsciously are actually impossible, a priori.

Perhaps conscious experiences (e.g., nausea, blue versus red) are easier to explain by appealing to, not our physical world, but the bizarre world of neurons, a world operating at vastly different size and speed scales. Much as a classroom model of the solar system that cannot not instantiate the critical phenomenon (strong gravitational fields) that glues our solar system together, the scale of our everyday human experience is far different from that in which consciousness arises (fast neurons interacting with each other). In other words, there is nothing that we can perceive in everyday life that works as fast, and in such an interactive manner, as the functional units of our brain.

Regarding the speed variable, our conscious experience is far slower than whatever processes that give rise to it. Perhaps some property may be arising from the extremely fast speeds of neurons and their networks that cannot happen at the slower speed of our everyday existence, which is the only environment we evolved to understand. The cause and effect relationships among billiard balls striking each other, which we evolved to be capable of understanding, also occurs at a slower scale than the workings of neurons. Returning to the topic of physics, it is important to appreciate that gravity seemed to be a conceptual mystery (dubbed ‘action at a distance’) until Einstein proved that our basic assumptions about it were wrong: space is not ‘empty’ but actually has a fabric that is warped by mass, giving rise to the phenomenon we identify as gravity [27]. Our assumptions about how things work (and cannot work) at the ‘human scale’ of existence might not be applicable to the smaller, faster scale of the world of neurons.

Regarding the speed of neural activity, it is important to appreciate that the puzzle of the “mind-body” problem is the same whether the tokens (conscious contents) differ from each other qualitatively or quantitatively [29]. This is an important notion because we know that the brain can implement codes that are quantitative in nature. Negro emphasizes, “​The brain has a bias towards a rhythmic mode of operation.” Specifically [30], it has been proposed that consciousness depends on, for example, “precise synchronization of oscillatory neuronal responses in the high frequency range (beta, gamma)”. Singer [30] adds, “brain states compatible with conscious processing should be characterized by a high degree of synchrony”. Negro emphasizes that sustained and widely distributed voltage deflections, increase of beta synchrony and gamma power correspond to a widely distributed cortical activity associated with conscious experiences.

Moreover, a group of neurons receiving information from another brain region cannot “see,” in a sense, the anatomical tracts connecting the two regions. Receiving neurons cannot see whether the afference stems from tracts that are visual or auditory. Hence, the receiving neurons must use some other kind of information (perhaps frequencies) to identify whether the information being received is of one kind or another (e.g., visual versus auditory).

We have delineated only a handful of the many problems encountered when attempting to understand consciousness from a scientific point of view. Paulo Negro's blueprint provides the reader with a wonderful journey in which, regarding these and many other challenges, no stone is left unturned and in which priceless clues and thoughtful insights about the true nature of consciousness are revealed, chapter after chapter. To navigate the mounting scientific findings regarding consciousness, and the growing number of theoretical frameworks that attempt to explain these findings, a blueprint for consciousness is essential, now more than ever.

Ezequiel Morsella ¹
Department of Psychology
San Francisco State University, CA
USA

Department of Neurology
University of California, CA
USA

and

Ngoc-Cam T. Bui
San Francisco State University, CA
USA

^[1]EZEQUIEL MORSELLA is a theoretician and experimentalist who has devoted his entire career to the investigation of differences in the brain between conscious and unconscious circuits that control human action. He is the lead author of the Oxford Handbook of Human Action (2009, Oxford University Press) and was the editor of the Festschrift in honor of Robert M. Krauss. His research has appeared in leading journals in neuroscience and experimental psychology, including Psychological Review and Behavioral and Brain Sciences. After his undergraduate studies at the University of Miami, he carried out his doctoral and postdoctoral studies at Columbia University and Yale University, respectively.  He is an Associate Professor in the Department of Psychology at San Francisco State and an Assistant Adjunct Professor in the Department of Neurology at the University of California, San Francisco.