Theories of consciousness: A concise overview

The Equations for Consciousness: A Reply to “Tracking the Travels,” a Review of <i>Journey of the Mind</i>

EDITORIAL article Front. Psychol., 01 September 2011 | https://doi.org/10.3389/fpsyg.2011.00191

Exploring the limits to our understanding of whether fish feel pain.

GENERAL COMMENTARY article Front. Psychol., 19 February 2015Sec. Cognition https://doi.org/10.3389/fpsyg.2015.00179

Emotional states of consciousness, or what are typically called emotional feelings, are traditionally viewed as being innately programmed in subcortical areas of the brain, and are often treated as different from cognitive states of consciousness, such as those related to the perception of external stimuli. We argue that conscious experiences, regardless of their content, arise from one system in the brain. In this view, what differs in emotional and nonemotional states are the kinds of inputs that are processed by a general cortical network of cognition, a network essential for conscious experiences. Although subcortical circuits are not directly responsible for conscious feelings, they provide nonconscious inputs that coalesce with other kinds of neural signals in the cognitive assembly of conscious emotional experiences. In building the case for this proposal, we defend a modified version of what is known as the higher-order theory of consciousness.

Although subjective conscious experience and introspection have long been considered unscientific and banned from psychology, they are indispensable in scientific practice. These terms are used in scientific contexts today; however, their meaning remains vague, and earlier objections to the distinction between conscious experience and unconscious processing, remain valid. This also applies to the distinction between conscious visual perception and unconscious visual processing. Damage to the geniculo-striate pathway or the visual cortex results in a perimetrically blind visual hemifield contralateral to the damaged hemisphere. In some cases, cerebral blindness is not absolute. Patients may still be able to guess the presence, location, shape or direction of movement of a stimulus even though they report no conscious visual experience. This “unconscious” ability was termed “blindsight”. The present paper demonstrates how the term conscious visual experience can be introduced in a logically precise and methodologically correct way and becomes amenable to scientific examination. The distinction between conscious experience and unconscious processing is demonstrated in the cases of conscious vision and blindsight. The literature on “blindsight” and its neurobiological basis is reviewed. It is shown that blindsight can be caused by residual functions of neural networks of the visual cortex that have survived cerebral damage, and may also be due to an extrastriate pathway via the midbrain to cortical areas such as areas V4 and MT/V5.

Towards solving the hard problem of consciousness: The varieties of brain resonances and the conscious experiences that they support

In every country in the world we teach our children that they belong to a certain nation and religion. The fact that we all live on the same planet Earth is not taken into consideration. The result is that we raise people with narrow personal identification, which can always be manipulated and used for violence and war with people of other nations and religions. In order to stop this centuries-long destruction we have to raise new generations that will first belong to the planetary society and second to a certain nation or religion. In the today’s educational system worldwide we mostly develop the rational analytic experience of the world, while the conscious synthetic experience if left aside. In order to strengthen the integration forces between people of this planet the scientific analytic experience needs to be enriched with conscious synthetic experience of the world. Conscious experience has a dimension of “sacredness”; one discovers his/her deep connectedness with other human beings, the nature and the universe. This experience of oneness is the basis for a peaceful planetary society living in cohabitation with nature. Key words: Perception, experience, observer, observing, rational mind, consciousness, watching, witnessing, self-experience, mind, time, timeless, oneness, planetary society, dual-aspect-dual-mode PE-SE framework, proto-experience, subjective experience, peace, happiness, war, suffering.

Theories of consciousness using neurobiological data or being influenced by these data have been focused either on states of consciousness or contents of consciousness. These theories have occasionally used evidence from psychophysical phenomena where conscious experience is a dependent experimental variable. However, systematic catalog of many such relevant phenomena has not been offered in terms of these theories. In the perceptual retouch theory of thalamocortical interaction, recently developed to become a blend with the dendritic integration theory, consciousness states and contents of consciousness are explained by the same mechanism. This general-purpose mechanism has modulation of the cortical layer-5 pyramidal neurons that represent contents of consciousness as its core. As a surplus, many experimental psychophysical phenomena of conscious perception can be explained by the workings of this mechanism. Historical origins and current views inherent in this theory are presented and reviewed.

The problem of consciousness is mostly regarded as identical to the mind-body problem. According to Chalmers’ philosophical arguments, the hard problem of consciousness lies in establishing and explaining the link between physical processes and conscious experiences, via psychological processes. A brief history of various theories of consciousness is given and a selection of theories are tested against Zeman’s three fundamental intuitions and Chalmers’ controversial zombie argument. The hard problem of consciousness is further described using Levine’s notion of an explanatory gap between physical matter and conscious experience, through the first and third persons. Various states, contents, levels and processes of consciousness are summarised, including Damasio and Meyer’s dual perspective for defining consciousness. Tart’s three definitions do not entirely describe altered states of consciousness. While the challenge of finding the core function of human and animal sleep remains unknown when tested under the null hypothesis, studies on the neural correlates of consciousness during meditation have revealed neuroplasticity effects. The synchrony of gamma brain oscillations reflecting various styles of meditation or attention, also known as the binding problem, may be related to conscious experiences. This binding problem with gamma brain oscillatory synchronization also arises in relation to sensory awareness or perception, affecting the perception of time and hallucinatory experiences in various disorders of consciousness such as severe schizophrenic and deja vu (in healthy or epileptic) patients. In conjunction with medication treatments, music therapy is often useful in accelerating the healing process in most such disorders of consciousness. It is still unknown how this sensory awareness to music is perceived in medicated patients suffering from disorders of consciousness. More clinically elusive are near death experiences, in which consciousness persists independently of brain function, where there is no scientific basis for such consciousness to exist and no physiological or psychological model that can explain it. Near death experiences can be regarded as a special state of consciousness, which provides further evidence that the consciousness problem may be very close to the mind-body problem that originates in Descartes’ classic theory of dualism and is transformed into Chalmers’ contemporary theory of natural dualism. The final section of this chapter offers an overview of all invited chapters.

This chapter describes the mechanisms behind conscious experiences, emphasizing the Neural Binding and Coherence (NBC) theory. It explores how neural representation, binding, coherence, and competition interact to create conscious phenomena. Using smell, hunger, loneliness, and self-awareness as examples, the chapter illustrates how these mechanisms contribute to component consciousness and compound experiences. The concept of ‘recurring emergence’ is central, highlighting how interactions within neural systems produce qualitative novelties like conscious states. The chapter also examines evolutionary functions, explaining how conscious experiences, such as smell aiding survival or hunger driving action, enhance biological fitness. Through detailed analyses, it connects abstract concepts like self-awareness to neural processes, arguing for consciousness as a product of neural mechanisms, in contrast to mystical, dualist, or panpsychist explanations.

The aim of the study was to investigate differences in cortical networks based on the state of consciousness. Five subjects performed a serial-awakening paradigm with electroencephalography (EEG) recordings. We considered four states of consciousness: (1) non-rapid eye movement (NREM) sleep with no conscious experience, (2) NREM sleep with conscious experience, (3) rapid eye movement (REM) sleep with conscious experience, and (4) wakefulness. We applied graph theoretical analysis to explore the cortical connectivity and network properties in five frequency bands. Connectivity between EEG channels was evaluated with the weighted phase lag index (wPLI). The characteristic path length, transitivity, and clustering coefficient were computed to evaluate functional integration and segregation of the associated brain network. There were no significant differences in wPLI among the four states of consciousness. In the beta band, functional integration in wakefulness was higher than in NREM sleep. Regarding functional segregation, in the theta band, transitivity and clustering coefficient in NREM sleep with no conscious experience were stronger than in wakefulness or REM sleep, but clustering in the beta band showed an opposite effect. The observed differences may be related to cortical bistability and add to previously observed neural correlates of consciousness.

Naturalism and transcendentalism in the naturalization of phenomenology

Multiple Perspectives on Consciousness for Cognitive Science Richard A. Carlson (racarlson@psu.edu) Department of Psychology, Penn State University 613 Moore Building, University Park, PA 16802 USA The huge contemporary literature on consciousness spans multiple disciplines, including psychology, philosophy, and neuroscience. This tutorial will introduce participants to major proposals about consciousness, and their empirical and methodological implications. The goal is to prepare participants to explore the consciousness literature in greater depth. Our consideration of perspectives on consciousness will be organized by considering how these perspectives address core questions about consciousness, including: (a) How can subjectivity and agency be accommodated in a scientific theory of consciousness? (b) How can conscious and nonconscious or unconscious processes and representations be systematically distinguished? (c) How can conscious mental states be assessed or measured? (d) How can dissociations and impairments of consciousness be understood? The literatures to be considered address these questions in analytic, functional, computational, and implementational terms. Philosophical Perspectives Philosophers approach the problem of consciousness from a variety of analytic perspectives, some focusing on contemporary formulations of the mind-body problem and others on analyses of subjective experience. Among the philosophical perspectives we will consider are John Searle’s (1992) analysis of consciousness in terms of intentionality, David Chalmer’s (1996) distinction between “easy” and “hard” problems of consciousness, David Rosenthal’s (1993) “higher order thought” proposal, and Daniel Dennett’s (1991) “multiple drafts” theory of consciousness. Neuroscience Perspectives Neuroscientists have made a wide variety of proposals concerning the neural correlates of consciousness (NCC). A starting assumption is that a subset of current neural activity is correlated with current conscious experience. There is controversy, however, concerning how that subset is to be identified. For example, the NCC might be limited to particular types of cells or anatomical structures, or comprise global patterns of synchronized neural activity. We will consider recent proposals concerning NCC by Crick and Koch (1998), Damasio (2000), and Edelman and Tononi Psychological Perspectives Psychological perspectives on consciousness generally focus on functionally-defined aspects of cognition. For example, psychologists have identified consciousness with working memory (Baars, 1988), attention (Schneider & Pimm-Smith, 1997), metacognition (Nelson, 1996), and with the structure of mental states (Carlson, 1997). Cognitive research often focuses on distinguishing conscious and nonconscious influences on psychological processes such as learning (Dienes & Berry, 1997) and perception (Merikle, Smilek, & Eastwood, 2001). This research has generated a rich literature on methods for assessing consciousness. References Baars, B. J. (1988). A cognitive theory of consciousness. New York: Cambridge University Press. Carlson, R. A. (1997). Experienced Cognition. Mahwah, NJ: Lawrence Erlbaum Associates. Chalmers, D. (1996). The conscious mind. Oxford: Oxford University Press. Crick, F., & Koch, C. (1998). Consciousness and neuroscience. Cerebral Cortex, 8, 97-107. Damasio, A. R. (2000). A neurobiology for consciousness. In T. Metzinger (Ed.), Neural correlates of consciousness Cambridge, MA: The MIT Press. Dienes, Z., & Berry, D. (1997). Implicit learning: Below the subjective threshold. Psychonomic Bulletin and Review, 4, Dennett, D. C. (1991). Consciousness explained. Boston: Little, Brown and Company. Edelman, G. M., & Tononi, G. (2000). Reentry and the dynamic core: Neural correlates of conscious experience. In T. Metzinger (Ed.), Neural correlates of consciousness. Cambridge, MA: The MIT Press. Merikle, P. M., Smilek, D., & Eastwood, J. D. (2001). Perception without awareness: perspectives from cognitive psychology. Cognition, 79, 115-134. Nelson, T. O. (1996). Consciousness and metacognition. American Psychologist, 51, 102-116. Rosenthal, D. M. (1993). Thinking that one thinks. In M. Davies, & G. W. Humphreys (Eds.), Consciousness: Psychological and philosophical essays. Oxford: Blackwell. Searle, J. R. (1992). The rediscovery of the mind. Cambridge, MA: The MIT Press. Schneider, W., & Pimm-Smith, M. (1997). Consciousness as a message aware control mechanism to modulate cognitive processing. J. Cohen, & J. Schooler (Eds.), Scientific approaches to consciousness: The 25th Carnegie Symposium on Cognition. Mahwah, NJ: Erlbaum.

Consciousness and the Novel: Connected Essays, by David Lodge; 320 pp. Cambridge, Mass.: Harvard University Press, 2002, $24.95 boards, $16.95 paper. Fictional Minds, by Alan Palmer; 275 pp. Lincoln and London: University of Nebraska Press, 2004, $45.00. Radiant Cool: A Novel Theory of Consciousness, by Dan Lloyd; 357 pp. Cambridge, Mass.: The MIT Press, 2004, $24.95 boards, $14.95 paper. What contributions can fiction make to the representation and investigation of conscious experience? Might fiction help us to develop and advance new theories about the nature of consciousness? And might such theories, in turn, inform our understanding of the process of reading fiction? Three recent volumes—one by English critic and novelist, David Lodge; another by literary theorist, Alan Palmer; and a third by philosopher and (now) novelist, Dan Lloyd—raise these important, genre-bending questions, and they offer challenging if not always convincing answers to them. More generally, these volumes make valuable contributions to the fruitful cross-pollination that has developed between philosophers, scientists, literary theorists, and novelists who are interested in the nature of consciousness. Lodge's new collection of essays is called Consciousness and the Novel: Connected Essays, and like all of the criticism he has written since the late eighties, this volume is intended for a general audience, not for [End Page 299] literary theorists. The title essay, "Consciousness and the Novel," is a revised version of the Richard Ellman Lectures in Modern Literature that Lodge gave at Emory University in 2001, and the other nine essays, all previously published, cover such topics as Howards End; the novels of Evelyn Waugh; The Letters of Kingsley Amis; Martin Amis's memoir, Experience; and the relationship between literature and criticism. I will focus on "Consciousness and the Novel." Lodge's thesis in this essay is that novels play an essential role in our exploration of the nature of human consciousness. This thesis is certainly true, but it is also entirely banal. Much more interesting is what Lodge says in support of it. He argues that because of the unique representative possibilities of the novel, conscious experiences can be represented more effectively in novels than they can be in scientific writing. Taken literally, as an assertion about the relative representational power of novels and scientific discourse, this is extremely implausible. However, taken more loosely—as an invitation to those of us interested in consciousness to take a closer look at the ways conscious experiences are represented in novels—Lodge's claim is sensible and appealing. I will consider the literal reading of Lodge's claim first and then turn to the looser one. It is undoubtedly true that, as a whole, novelists devote more energy to representing conscious experiences than writers of scientific discourse do. However, science writers can use whatever techniques best serve their aims, including the aim of describing conscious experiences, so there is no reason to think that conscious experiences can, in principle, be represented more effectively in novels than in broadly scientific discourse. Given that Lodge discusses such creative science writers as Antonio Damasio, Daniel Dennett, and Steven Pinker in the course of his essay, it is surprising and disappointing to find him caricature scientific writing in the following way: "science . . . is a third-person discourse. The first-person pronoun is not used in scientific papers. If there were any hint of qualia in a scientific paper . . . it would be edited out" (p. 11). Qualia are the supposedly subjective qualitative aspects of conscious experiences. How the plucked string of a cello sounds to you; how the rotting fish in the garbage smells to you; and how it feels for you to inch down into the smooth, almost-too-hot water of a perfect bubble bath—these are all (supposedly) examples of qualia. Lodge is simply mistaken when he says that there is no hint of qualia in scientific writing. There is no consensus about whether qualia can be explained scientifically. In fact, there is no consensus about whether they exist. [End Page...