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Consciousness, at its simplest, is
sentience Sentience is the capacity to experience feeling Feeling was originally used to describe the physical sensation of touch through either experience or perception. The word is also used to describe other experiences, such as "Emotion, a feeling of ...
or
awareness Awareness is the state of being conscious of something. More specifically, it is the ability to directly know and perceive, to feel, or to be cognizant of events. Another definition describes it as a state wherein a subject is aware of some infor ...

awareness
of internal and external existence. Despite millennia of analyses, definitions, explanations and debates by philosophers and scientists, consciousness remains puzzling and controversial, being "at once the most familiar and lso themost mysterious aspect of our lives". Perhaps the only widely agreed notion about the topic is the intuition that consciousness exists. Opinions differ about what exactly needs to be studied and explained as consciousness. Sometimes, it is synonymous with the
mind The mind is the set of faculties responsible for mental phenomena A phenomenon (; plural phenomena) is an observable fact or event. The term came into its modern philosophical Philosophy (from , ) is the study of general and fun ...

mind
, and at other times, an aspect of mind. In the past, it was one's "inner life", the world of
introspection Introspection is the examination of one's own conscious , an English Paracelsian Paracelsianism (also Paracelsism; German: ') was an early modern History of medicine, medical movement based on the theories and therapies of Paracelsus. It de ...
, of private
thought In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, an ...

thought
,
imagination Imagination is the ability to produce and simulate novel objects, sensations, and ideas in the mind The mind is the set of faculties responsible for mental Phenomenon, phenomena. Often the term is also identified with the phenomena themselves. ...

imagination
and volition. Today, it often includes any kind of
cognition Cognition () refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses many aspects of intellectual function Intellectual functioning refers to the "general men ...
,
experience Experience refers to conscious , an English Paracelsian Paracelsianism (also Paracelsism; German: ') was an early modern History of medicine, medical movement based on the theories and therapies of Paracelsus. It developed in the second half ...

experience
,
feeling Feeling was originally used to describe the physical sensation of touch through either experience or perception. The word is also used to describe other experiences, such as "Emotion, a feeling of warmth" and of sentience in general. In psychology ...

feeling
or
perception Perception (from the Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" o ...

perception
. It may be awareness, awareness of awareness, or
self-awareness In philosophy of self The philosophy of self is the study of the many conditions of identity Identity may refer to: Social sciences * Identity (social science), personhood or group affiliation in psychology and sociology Group expre ...
either continuously changing or not. There might be different levels or orders of consciousness, or different kinds of consciousness, or just one kind with different features. Other questions include whether only humans are conscious, all animals, or even the whole universe. The disparate range of research, notions and speculations raises doubts about whether the right questions are being asked. Examples of the range of descriptions, definitions or explanations are: simple
wakefulness Wakefulness is a daily recurring brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exi ...
, one's sense of
self The self is an individual person as the object of its own reflective consciousness Consciousness, at its simplest, is or of internal and external existence. Despite millennia of analyses, definitions, explanations and debates by philosoph ...

self
hood or
soul In many religious, philosophical, and myth Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. The main characters in myths are usually non-humans, such as ...

soul
explored by " looking within"; being a metaphorical "
stream A stream is a body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmål (, ; literally "book tongue") is an official written standard for the No ...
" of contents, or being a
mental state A mental state, or a mental property, is a state of mind The mind is the set of faculties responsible for mental phenomena A phenomenon (; plural phenomena) is an observable fact or event. The term came into its modern philosophical ...
,
mental event A mental event is any event that happens within the mind of a Consciousness, conscious individual. Examples include thoughts, feelings, decisions, dreams, and realizations. Some believe that mental events are not limited to human thought but can ...
or
mental process Cognition () refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses many aspects of intellectual function Intellectual functioning refers to the "general men ...
of the brain; having
phanera ''Phanera'' is a genus of flowering plants in the legume family, Fabaceae. It belongs to the subfamily Cercidoideae. This genus differs from ''Bauhinia'' in being vines or lianas, generally with tendrils and a lobed rather than spathaceous calyx, ...
or
qualia In philosophy of mind Philosophy of mind is a branch of that studies the and nature of the and its relationship with the body. The is a paradigmatic issue in philosophy of mind, although a number of other issues are addressed, such as the ...
and
subjectivity Subjectivity in a philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical or mental reality Reality is the sum ...
; being the ' something that it is like' to 'have' or 'be' it; being the "inner theatre" or the executive control system of the mind.


Inter-disciplinary perspectives

Western philosophers since the time of
Descartes
Descartes
and
Locke
Locke
have struggled to comprehend the nature of consciousness and how it fits into a larger picture of the world. These issues remain central to both
continental Continental may refer to: Places * Continent * Continental, Arizona, a small community in Pima County, Arizona, US * Continental, Ohio, a small town in Putnam County, US Arts and entertainment * Continental (album), ''Continental'' (album), an alb ...
and analytic philosophy, in
phenomenology Phenomenology may refer to: * Empirical research, when used to describe measurement methods in some sciences * An empirical relationship or phenomenological model * Phenomenology (architecture), based on the experience of building materials and the ...
and the
philosophy of mind Philosophy of mind is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, a ...

philosophy of mind
, respectively. Some basic questions include: whether consciousness is the same kind of thing as matter; whether it may ever be possible for computing machines like computers or robots to be conscious; how consciousness relates to language; how consciousness as Being relates to the world of experience; the role of the self in experience; whether individual thought is possible at all; and whether the concept is fundamentally coherent. Recently, consciousness has also become a significant topic of interdisciplinary research in
cognitive science Cognitive science is the interdisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of two or more academic discipline An academic discipline or academic field is a subdivision of knowledge that is Educ ...

cognitive science
, involving fields such as
psychology Psychology is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in the real world. ...

psychology
,
linguistics Linguistics is the scientific study of language A language is a structured system of communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo ...

linguistics
, anthropology,
neuropsychology Neuropsychology is a branch of psychology. It is concerned with how a person's cognition and behavior are related to the brain and the rest of the nervous system. Professionals in this branch of psychology often focus on how injuries or illness ...
and
neuroscience Neuroscience is the scientific study of the nervous system In biology, the classical doctrine of the nervous system determines that it is a Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sens ...

neuroscience
. The primary focus is on understanding what it means biologically and psychologically for
information Information is processed, organised and structured data Data (; ) are individual facts A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to c ...

information
to be present in consciousness—that is, on determining the neural and psychological correlates of consciousness. The majority of experimental studies assess consciousness in humans by asking subjects for a verbal report of their experiences (e.g., "tell me if you notice anything when I do this"). Issues of interest include phenomena such as
subliminal perception Subliminal stimuli () (the prefix sub- literally means "below, or less than"), contrary to wikt:supraliminal, supraliminal stimuli or "above threshold", are any sensory Stimulus (physiology), stimuli below an individual's Sensory threshold, thresho ...
,
blindsight Blindsight is the ability of people who are cortically blind due to lesions in their striate cortex The visual cortex of the brain A brain is an organ (anatomy), organ that serves as the center of the nervous system in all vertebrate and most i ...
, denial of impairment, and
altered states of consciousness An altered state of consciousness (ASC), also called altered state of mind or mind alteration, is any condition which is significantly different from a normal waking state. By 1892, the expression was in use in relation to hypnosis File: ...
produced by
alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a Saturated and unsaturated compounds, saturated carbon atom. The term alcohol originally referred to the primary alcohol ethan ...
and
other drugs Other most often refers to: * Other (philosophy), a concept in psychology and philosophy Other or The Other may also refer to: Books * The Other (Tryon novel), ''The Other'' (Tryon novel), a 1971 horror novel by Tom Tryon * The Other (short story ...
, or spiritual or meditative techniques. In
medicine Medicine is the science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge), skills (proced ...

medicine
, consciousness is assessed by observing a patient's arousal and responsiveness, and can be seen as a continuum of states ranging from full alertness and comprehension, through disorientation,
delirium Delirium (also known as acute confusional state) is an organically caused decline from a previous baseline mental functioning, that develops over a short period of time, typically hours to days. Delirium is a syndrome A syndrome is a set of me ...
, loss of meaningful communication, and finally loss of movement in response to painful
stimuli A stimulus is something that causes a physiological response. It may refer to: *Stimulation Stimulation is the encouragement of development or the cause of activity generally. For example, "The press provides stimulation of political discourse." ...
. Issues of practical concern include how the presence of consciousness can be assessed in severely ill, comatose, or anesthetized people, and how to treat conditions in which consciousness is impaired or disrupted. The degree of consciousness is measured by standardized behavior observation scales such as the
Glasgow Coma Scale The Glasgow Coma Scale (GCS) is a clinical scale used to reliably measure a person's level of consciousness after a brain injury. The GCS assesses a person based on their ability to perform eye movements, speak, and move their body. These thre ...
.


Etymology

In the late 20th century, philosophers like Hamlyn, Rorty, and Wilkes have disagreed with
Kahn Kahn is a surname of German language, German origin. ''Kahn'' means "small boat", in German. It is also a Germanized form of the Jewish surname Cohen (surname), Cohen, another variant of which is ''Cahn''.Hardie and Modrak as to whether
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questio ...

Aristotle
even had a concept of consciousness. Aristotle does not use any single word or
terminology Terminology is a general word for the group of specialized words or meanings relating to a particular field, and also the study of such terms and their use. This is also known as terminology science. Terms are words and compound words or multi-w ...

terminology
to name the
phenomena A phenomenon (; plural phenomena) is an observable fact or event. The term came into its modern philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, existence, knowledge ...

phenomena
; it is used only much later, especially by
John Locke John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Enlightenment Enlightenment, enlighten or enlightened may refer to: Age of Enlightenment * ...

John Locke
.
Caston Caston is a village and civil parish in the English county of Norfolk. It covers an area of and had a population of 459 in 174 households at the United Kingdom Census 2001, 2001 census, decreasing to a population of 443 also in 174 households at ...
contends that for Aristotle, was somewhat the same as what modern philosophers call consciousness. The origin of the modern concept of consciousness is often attributed to Locke's ''
Essay Concerning Human Understanding ''An Essay Concerning Human Understanding'' is a work by John Locke John Locke (; 29 August 1632 – 28 October 1704) was an English philosopher and physician, widely regarded as one of the most influential of Age of Enlightenmen ...
'', published in 1690. Locke defined consciousness as "the perception of what passes in a man's own mind". His essay influenced the 18th-century view of consciousness, and his definition appeared in
Samuel Johnson Samuel Johnson (18 September 1709  – 13 December 1784), often called Dr Johnson, was an English writer who made lasting contributions as a poet, playwright, essayist, moralist, critic A critic is a person who communicates an asse ...
's celebrated ''
Dictionary A dictionary is a listing of lexemes from the lexicon of one or more specific languages, often arranged Alphabetical order, alphabetically (or by radical-and-stroke sorting, radical and stroke for ideographic languages), which may include in ...
'' (1755). "Consciousness" (French: ''conscience'') is also defined in the 1753 volume of
Diderot Denis Diderot (; 5 October 171331 July 1784) was a French philosopher, art critic, and writer, best known for serving as co-founder, chief editor, and contributor to the ''Encyclopédie'' along with Jean le Rond d'Alembert. He was a prominent fi ...

Diderot
and
d'Alembert Jean-Baptiste le Rond d'Alembert (; ; 16 November 1717 – 29 October 1783) was a French mathematician, mechanician A mechanician is an engineer or a scientist working in the field of mechanics, or in a related or sub-field: engineering or com ...

d'Alembert
's
Encyclopédie ''Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers'' (English: ''Encyclopedia, or a Systematic Dictionary of the Sciences, Arts, and Crafts''), better known as ''Encyclopédie'', was a general encyclopedia ...

Encyclopédie
, as "the opinion or internal feeling that we ourselves have from what we do". The earliest English language uses of "conscious" and "consciousness" date back, however, to the 1500s. The English word "conscious" originally derived from the Latin ''conscius'' (''con-'' "together" and ''scio'' "to know"), but the Latin word did not have the same meaning as the English word—it meant "knowing with", in other words, "having joint or common
knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to correspond to e ...
with another". There were, however, many occurrences in Latin writings of the phrase ''conscius sibi'', which translates literally as "knowing with oneself", or in other words "sharing knowledge with oneself about something". This phrase had the figurative meaning of "knowing that one knows", as the modern English word "conscious" does. In its earliest uses in the 1500s, the English word "conscious" retained the meaning of the Latin ''conscius''. For example,
Thomas Hobbes Thomas Hobbes ( ; sometimes known as Thomas Hobbes of Malmesbury; 5 April 1588 – 4 December 1679) was an English English usually refers to: * English language English is a West Germanic languages, West Germanic language first sp ...
in ''
Leviathan Leviathan (; , ) is a sea serpent A sea serpent or sea dragon is a type of dragon A dragon is a large, snake, serpentine, legendary creature that appears in the folklore of many cultures worldwide. Beliefs about dragons vary consid ...
'' wrote: "Where two, or more men, know of one and the same fact, they are said to be Conscious of it one to another." The Latin phrase ''conscius sibi'', whose meaning was more closely related to the current concept of consciousness, was rendered in English as "conscious to oneself" or "conscious unto oneself". For example, Archbishop Ussher wrote in 1613 of "being so conscious unto myself of my great weakness". Locke's definition from 1690 illustrates that a gradual shift in meaning had taken place. A related word was '' conscientia'', which primarily means
moral A moral (from Latin ''morālis'') is a message that is conveyed or a lesson to be learned from a narrative, story or wikt:event, event. The moral may be left to the hearer, reader, or viewer to determine for themselves, or may be explicitly enca ...

moral
conscience Conscience is a cognitive process that elicits emotion and rational associations based on an individual's ethics, moral philosophy or value system. Conscience stands in contrast to elicited emotion or thought due to associations based on immedi ...

conscience
. In the literal sense, "conscientia" means knowledge-with, that is, shared knowledge. The word first appears in Latin juridical texts by writers such as
Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Ancient Rome, Roman statesman, lawyer, scholar, philosopher and Academic skepticism, Academic Skeptic, who tried to uphold optimate principles during crisis of ...

Cicero
. Here, ''conscientia'' is the knowledge that a witness has of the deed of someone else.
René Descartes René Descartes ( or ; ; Latinized Latinisation or Latinization can refer to: * Latinisation of names, the practice of rendering a non-Latin name in a Latin style * Latinisation in the Soviet Union, the campaign in the USSR during the 1920s ...

René Descartes
(1596–1650) is generally taken to be the first philosopher to use ''conscientia'' in a way that does not fit this traditional meaning. Descartes used ''conscientia'' the way modern speakers would use "conscience". In ''Search after Truth'' (', Amsterdam 1701) he says "conscience or internal testimony" (''conscientiâ, vel interno testimonio'').


The problem of definition

The dictionary definitions of the word ''consciousness'' extend through several centuries and reflect a range of seemingly related meanings, with some differences that have been controversial, such as the distinction between 'inward awareness' and 'perception' of the physical world, or the distinction between 'conscious' and 'unconscious', or the notion of a "mental entity" or "mental activity" that is not physical. The common usage definitions of ''consciousness'' in ''
Webster's Third New International Dictionary ''Webster's Third New International Dictionary of the English Language, Unabridged'' (commonly known as ''Webster's Third'', or ''W3'') was published in September 1961. It was edited by Philip Babcock Gove Philip Babcock Gove (1902–1972) was an A ...
'' (1966 edition, Volume 1, page 482) are as follows: #* ''awareness or perception of an inward psychological or spiritual fact; intuitively perceived knowledge of something in one's inner self'' #* ''inward awareness of an external object, state, or fact'' #* ''concerned awareness;'' INTEREST, CONCERN—''often used with an attributive noun .g. class consciousness' #''the state or activity that is characterized by sensation, emotion, volition, or thought; mind in the broadest possible sense; something in nature that is distinguished from the physical'' #''the totality in psychology of sensations, perceptions, ideas, attitudes, and feelings of which an individual or a group is aware at any given time or within a particular time span—''compare STREAM OF CONSCIOUSNESS #''waking life (as that to which one returns after sleep, trance, fever) wherein all one's mental powers have returned . . .'' #''the part of mental life or psychic content in psychoanalysis that is immediately available to the ego—''compare PRECONSCIOUS, UNCONSCIOUS The
Cambridge Dictionary The ''Cambridge Advanced Learner's Dictionary'' (unofficially ''Cambridge English Dictionary'' or ''Cambridge Dictionary'', abbreviated ''CALD'') was first published in 1995 under the name ''Cambridge International Dictionary of English'', by ...
defines consciousness as "''the state of understanding and realizing something.''" The
Oxford Living Dictionary Lexico is a website that provides a collection of dictionaries of English and Spanish produced by Oxford University Press (OUP), the publishing house of the University of Oxford. While the dictionaries on Lexico are made solely by OUP, the webs ...
defines consciousness as "''The state of being aware of and responsive to one's surroundings.''", "''A person's awareness or perception of something.''" and "''The fact of awareness by the mind of itself and the world.''" Philosophers have attempted to clarify technical distinctions by using a
jargon Jargon is the specialized terminology associated with a particular field or area of activity. Jargon is normally employed in a particular Context (language use), communicative context and may not be well understood outside that context. The conte ...
of their own. The ''
Routledge Encyclopedia of Philosophy Routledge () is a British multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a sov ...
'' in 1998 defines consciousness as follows: Many philosophers and scientists have been unhappy about the difficulty of producing a definition that does not involve circularity or fuzziness. In The ''Macmillan Dictionary of Psychology'' (1989 edition), Stuart Sutherland expressed a skeptical attitude more than a definition: A partisan definition such as Sutherland's can hugely affect researchers' assumptions and the direction of their work: Many philosophers have argued that consciousness is a unitary concept that is understood intuitively by the majority of people in spite of the difficulty in defining it. Others, though, have argued that the level of disagreement about the meaning of the word indicates that it either means different things to different people (for instance, the
objective Objective may refer to: * Objective (optics), an element in a camera or microscope * ''The Objective'', a 2008 science fiction horror film * Objective pronoun, a personal pronoun that is used as a grammatical object * Objective Productions, a Briti ...
versus
subjective Subjective may refer to: * Subjectivity, a subject's personal perspective, feelings, beliefs, desires or discovery, as opposed to those made from an independent, objective, point of view ** Subjective experience, the subjective quality of consciou ...
aspects of consciousness), or else it encompasses a variety of distinct meanings with no simple element in common.


Philosophy of mind

Most writers on the philosophy of consciousness have been concerned with defending a particular point of view, and have organized their material accordingly. For surveys, the most common approach is to follow a historical path by associating stances with the philosophers who are most strongly associated with them, for example, Descartes, Locke, Kant, etc. An alternative is to organize philosophical stances according to basic issues.


The coherence of the concept

Philosophers differ from non-philosophers in their intuitions about what consciousness is. While most people have a strong intuition for the existence of what they refer to as consciousness, skeptics argue that this intuition is false, either because the concept of consciousness is intrinsically incoherent, or because our intuitions about it are based in illusions.
Gilbert Ryle Gilbert Ryle (1900–1976) was a British philosopher, principally known for his critique of Cartesian dualism, for which he coined the phrase "ghost in the machine." He was a representative of the generation of British ordinary language philosoph ...
, for example, argued that traditional understanding of consciousness depends on a Cartesian dualist outlook that improperly distinguishes between mind and body, or between mind and world. He proposed that we speak not of minds, bodies, and the world, but of individuals, or persons, acting in the world. Thus, by speaking of "consciousness" we end up misleading ourselves by thinking that there is any sort of thing as consciousness separated from behavioral and linguistic understandings.


Types of consciousness

Ned Block Ned Joel Block (born 1942) is an American philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom'. The coining of the term ...

Ned Block
argued that discussions on consciousness often failed to properly distinguish ''phenomenal'' (P-consciousness) from ''access'' (A-consciousness), though these terms had been used before Block. P-consciousness, according to Block, is simply raw experience: it is moving, colored forms, sounds, sensations, emotions and feelings with our bodies and responses at the center. These experiences, considered independently of any impact on behavior, are called
qualia In philosophy of mind Philosophy of mind is a branch of that studies the and nature of the and its relationship with the body. The is a paradigmatic issue in philosophy of mind, although a number of other issues are addressed, such as the ...
. A-consciousness, on the other hand, is the phenomenon whereby information in our minds is accessible for verbal report, reasoning, and the control of behavior. So, when we
perceive Perception (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the powe ...

perceive
, information about what we perceive is access conscious; when we introspect, information about our thoughts is access conscious; when we
remember Remember may refer to: Film and television * ''Remember?'', a 1939 film starring Robert Taylor and Greer Garson * Remember (2015 film), ''Remember'' (2015 film), a Canadian film by Atom Egoyan, starring Christopher Plummer * Remember (1926 film), ...

remember
, information about the past is access conscious, and so on. Although some philosophers, such as
Daniel Dennett Daniel Clement Dennett III (born March 28, 1942) is an American philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom' ...

Daniel Dennett
, have disputed the validity of this distinction, others have broadly accepted it.
David Chalmers David John Chalmers (; born 20 April 1966) is an Australian Australians, colloquially referred to as "Aussies", are the citizens Citizenship is a relationship between an individual and a state to which the individual owes allegiance ...

David Chalmers
has argued that A-consciousness can in principle be understood in mechanistic terms, but that understanding P-consciousness is much more challenging: he calls this the
hard problem of consciousness The hard problem of consciousness is the problem of explaining why and how we have qualia In philosophy and certain models of psychology, qualia ( or ; singular form: quale) are defined as individual instances of Subjectivity, subjective, conscio ...
. Kong Derick has also stated that there are two types of consciousness: high level consciousness, which he attributes to the Mind and low level consciousness, which he attributes to the Submind. " Some philosophers believe that Block's two types of consciousness are not the end of the story.
William Lycan William G. Lycan (; born September 26, 1945) is an American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of America (USA), comm ...
, for example, argued in his book ''Consciousness and Experience'' that at least eight clearly distinct types of consciousness can be identified (organism consciousness; control consciousness; consciousness ''of''; state/event consciousness; reportability; introspective consciousness; subjective consciousness; self-consciousness)—and that even this list omits several more obscure forms. There is also debate over whether or not A-consciousness and P-consciousness always coexist or if they can exist separately. Although P-consciousness without A-consciousness is more widely accepted, there have been some hypothetical examples of A without P. Block, for instance, suggests the case of a "zombie" that is computationally identical to a person but without any subjectivity. However, he remains somewhat skeptical concluding "I don't know whether there are any actual cases of A-consciousness without P-consciousness, but I hope I have illustrated their conceptual possibility."


Consciousness in children

Of the eight types of consciousness in the Lycan classification, some are detectable in utero and others develop years after birth. Psychologist and educator William Foulkes studied children's dreams and concluded that prior to the shift in cognitive maturation that humans experience during ages five to seven, children lack the Lockean consciousness that Lycan had labeled "introspective consciousness" and that Foulkes labels "self-reflection." In a 2020 paper,
Katherine Nelson Katherine Nelson (1930 – August 10, 2018) was an American Developmental psychology, developmental psychologist, and professor. Education Nelson completed her dissertation research on the organization of free recall of verbal information in chi ...
and Robyn Fivush use "autobiographical consciousness" to label essentially the same faculty, and agree with Foulkes on the timing of this faculty's acquisition. Nelson and Fivush contend that "language is the tool by which humans create a new, uniquely human form of consciousness, namely, autobiographical consciousness."
Julian Jaynes Julian Jaynes (February 27, 1920 – November 21, 1997) was an American researcher in psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconsciou ...
had staked out these positions decades earlier. Citing the developmental steps that lead the infant to autobiographical consciousness, Nelson and Fivush point to the acquisition of "
theory of mind In psychology Psychology is the scientific Science (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area ar ...
," calling theory of mind "necessary for autobiographical consciousness" and defining it as "understanding differences between one's own mind and others' minds in terms of beliefs, desires, emotions and thoughts." They write, "The hallmark of theory of mind, the understanding of false belief, occurs ... at five to six years of age."


Mind–body problem

Mental processes (such as consciousness) and physical processes (such as brain events) seem to be correlated, however the specific nature of the connection is unknown. The first influential philosopher to discuss this question specifically was , and the answer he gave is known as
Cartesian dualismCartesian means of or relating to the French philosopher René Descartes—from his Latinized name ''Cartesius''. It may refer to: Mathematics * Cartesian closed category, a closed category in category theory *Cartesian coordinate system A C ...
. Descartes proposed that consciousness resides within an immaterial domain he called res cogitans (the realm of thought), in contrast to the domain of material things, which he called
res extensa ''Res extensa'' is one of the two Substance theory, substances described by René Descartes in his Cartesian dualism, Cartesian ontology (often referred to as "radical Mind-body dualism, dualism"), alongside ''Mental substance, res cogitans''. Tra ...

res extensa
(the realm of extension). He suggested that the interaction between these two domains occurs inside the brain, perhaps in a small midline structure called the
pineal gland The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland Endocrine glands are ductless glands of the endocrine system The endocrine system is a messenger system comprising feedback loops of the hormones released by inte ...

pineal gland
. Although it is widely accepted that Descartes explained the problem cogently, few later philosophers have been happy with his solution, and his ideas about the pineal gland have especially been ridiculed. However, no alternative solution has gained general acceptance. Proposed solutions can be divided broadly into two categories: dualist solutions that maintain Descartes' rigid distinction between the realm of consciousness and the realm of matter but give different answers for how the two realms relate to each other; and
monist Monism attributes oneness or singleness (Greek: μόνος) to a concept e.g., existence. Various kinds of monism can be distinguished: * Priority monism states that all existing things go back to a source that is distinct from them; e.g., ...
solutions that maintain that there is really only one realm of being, of which consciousness and matter are both aspects. Each of these categories itself contains numerous variants. The two main types of dualism are
substance dualism Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and takes up space * Substance th ...
(which holds that the mind is formed of a distinct type of substance not governed by the laws of physics) and
property dualism Property dualism: the exemplification of two kinds of property by one kind of substance Property dualism describes a category of positions in the philosophy of mind which hold that, although the world is composed of just one kind of substance the ...

property dualism
(which holds that the laws of physics are universally valid but cannot be used to explain the mind). The three main types of monism are
physicalism In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical reality Reality is the sum or aggregate of all that is ...
(which holds that the mind consists of matter organized in a particular way),
idealism In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, lan ...

idealism
(which holds that only thought or experience truly exists, and matter is merely an illusion), and
neutral monism Neutral monism is an umbrella term for a class of metaphysical Metaphysics is the branch of philosophy that studies the first principles of being, identity and change, space and time, causality, necessity and possibility. It includes questions ...
(which holds that both mind and matter are aspects of a distinct essence that is itself identical to neither of them). There are also, however, a large number of idiosyncratic theories that cannot cleanly be assigned to any of these schools of thought. Since the dawn of Newtonian science with its vision of simple mechanical principles governing the entire universe, some philosophers have been tempted by the idea that consciousness could be explained in purely physical terms. The first influential writer to propose such an idea explicitly was
Julien Offray de La Mettrie Julien Offray de La Mettrie (; November 23, 1709 – November 11, 1751) was a French physician A physician (American English), medical practitioner (English in the Commonwealth of Nations, Commonwealth English), medical doctor, or simply doc ...

Julien Offray de La Mettrie
, in his book ''
Man a Machine ''Man a Machine'' (French: ''L'homme Machine'') is a work of materialist philosophy by the 18th-century French physician and philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλό ...
'' (''L'homme machine''). His arguments, however, were very abstract. The most influential modern physical theories of consciousness are based on
psychology Psychology is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in the real world. ...

psychology
and
neuroscience Neuroscience is the scientific study of the nervous system In biology, the classical doctrine of the nervous system determines that it is a Complex system, highly complex part of an animal that coordinates its Behavior, actions and Sens ...

neuroscience
. Theories proposed by neuroscientists such as
Gerald Edelman Gerald Maurice Edelman (; July 1, 1929 – May 17, 2014) was an American biologist who shared the 1972 Nobel Prize in Physiology or Medicine for work with Rodney Robert Porter on the immune system. Edelman's Nobel Prize-winning research concerne ...
and
Antonio Damasio Antonio Damasio ( pt, António Damásio) is a Portuguese-American neuroscientist A neuroscientist (or neurobiologist) is a scientist A scientist is a person who conducts Scientific method, scientific research to advance knowledge in an Branch ...
, and by philosophers such as Daniel Dennett, seek to explain consciousness in terms of neural events occurring within the brain. Many other neuroscientists, such as
Christof Koch Christof Koch (; born November 13, 1956) is a German-American neuroscientist A neuroscientist (or neurobiologist) is a scientist who has specialised knowledge in neuroscience, a branch of biology that deals with the physiology, biochemistry, psy ...
, have explored the neural basis of consciousness without attempting to frame all-encompassing global theories. At the same time, computer scientists working in the field of
artificial intelligence Artificial intelligence (AI) is intelligence Intelligence has been defined in many ways: the capacity for abstraction Abstraction in its main sense is a conceptual process where general rules and concept Concepts are defined as abstra ...

artificial intelligence
have pursued the goal of creating digital computer programs that can simulate or embody consciousness. A few theoretical physicists have argued that classical physics is intrinsically incapable of explaining the holistic aspects of consciousness, but that
quantum theory Quantum theory may refer to: Science *Quantum mechanics Quantum mechanics is a fundamental theory A theory is a reason, rational type of abstraction, abstract thinking about a phenomenon, or the results of such thinking. The process of co ...
may provide the missing ingredients. Several theorists have therefore proposed
quantum mind The quantum mind or quantum consciousness is a group of hypotheses proposing that classical mechanics cannot explain consciousness. It posits that quantum mechanical, quantum-mechanical phenomena, such as quantum entanglement, entanglement and Quan ...
(QM) theories of consciousness. Notable theories falling into this category include the
holonomic brain theory Holonomic brain theory, also known as The Holographic Brain, is a branch of neuroscience investigating the idea that human consciousness is formed by quantum effects in or between brain cells. This is opposed by traditional neuroscience, which inve ...
of Karl H. Pribram, Karl Pribram and David Bohm, and the Orch-OR, Orch-OR theory formulated by Stuart Hameroff and Roger Penrose. Some of these QM theories offer descriptions of phenomenal consciousness, as well as QM interpretations of access consciousness. None of the quantum mechanical theories have been confirmed by experiment. Recent publications by G. Guerreshi, J. Cia, S. Popescu, and H. Briegel could falsify proposals such as those of Hameroff, which rely on quantum entanglement in protein. At the present time many scientists and philosophers consider the arguments for an important role of quantum phenomena to be unconvincing. Apart from the general question of the Hard problem of consciousness, "hard problem" of consciousness (which is, roughly speaking, the question of how mental experience can arise from a physical basis), a more specialized question is how to square the subjective notion that we are in control of our decisions (at least in some small measure) with the customary view of causality that subsequent events are caused by prior events. The topic of free will is the philosophical and scientific examination of this conundrum.


Problem of other minds

Many philosophers consider experience to be the essence of consciousness, and believe that experience can only fully be known from the inside, subjectively. But if consciousness is subjective and not visible from the outside, why do the vast majority of people believe that other people are conscious, but rocks and trees are not? This is called the problem of other minds. It is particularly acute for people who believe in the possibility of philosophical zombies, that is, people who think it is possible in principle to have an entity that is physically indistinguishable from a human being and behaves like a human being in every way but nevertheless lacks consciousness. Related issues have also been studied extensively by Greg Littmann of the University of Illinois,''The Culture and Philosophy of Ridley Scott'', Greg Littmann, pp. 133–144, Lexington Books (2013). and by Colin Allen (a professor at Indiana University) regarding the literature and research studying
artificial intelligence Artificial intelligence (AI) is intelligence Intelligence has been defined in many ways: the capacity for abstraction Abstraction in its main sense is a conceptual process where general rules and concept Concepts are defined as abstra ...

artificial intelligence
in androids.''Moral Machines'', Wendell Wallach and Colin Allen, 288 pages, Oxford University Press, USA (June 3, 2010), . The most commonly given answer is that we attribute consciousness to other people because we see that they resemble us in appearance and behavior; we reason that if they look like us and act like us, they must be like us in other ways, including having experiences of the sort that we do. There are, however, a variety of problems with that explanation. For one thing, it seems to violate the Occam's razor, principle of parsimony, by postulating an invisible entity that is not necessary to explain what we observe. Some philosophers, such as Daniel Dennett in an essay titled ''The Unimagined Preposterousness of Zombies'', argue that people who give this explanation do not really understand what they are saying. More broadly, philosophers who do not accept the possibility of zombies generally believe that consciousness is reflected in behavior (including verbal behavior), and that we attribute consciousness on the basis of behavior. A more straightforward way of saying this is that we attribute experiences to people because of what they can ''do'', including the fact that they can tell us about their experiences.


Animal consciousness

The topic of animal consciousness is beset by a number of difficulties. It poses the problem of other minds in an especially severe form, because non-human animals, lacking the ability to express human language, cannot tell humans about their experiences. Also, it is difficult to reason objectively about the question, because a denial that an animal is conscious is often taken to imply that it does not feel, its life has no value, and that harming it is not morally wrong. Descartes, for example, has sometimes been blamed for mistreatment of animals due to the fact that he believed only humans have a non-physical mind. Most people have a strong intuition that some animals, such as cats and dogs, are conscious, while others, such as insects, are not; but the sources of this intuition are not obvious, and are often based on personal interactions with pets and other animals they have observed. Philosophers who consider subjective experience the essence of consciousness also generally believe, as a correlate, that the existence and nature of animal consciousness can never rigorously be known. Thomas Nagel spelled out this point of view in an influential essay titled ''What Is it Like to Be a Bat?''. He said that an organism is conscious "if and only if there is something that it is like to be that organism—something it is like ''for'' the organism"; and he argued that no matter how much we know about an animal's brain and behavior, we can never really put ourselves into the mind of the animal and experience its world in the way it does itself. Other thinkers, such as Douglas Hofstadter, dismiss this argument as incoherent. Several psychologists and ethologists have argued for the existence of animal consciousness by describing a range of behaviors that appear to show animals holding beliefs about things they cannot directly perceive—Donald Griffin's 2001 book ''Animal Minds'' reviews a substantial portion of the evidence. On July 7, 2012, eminent scientists from different branches of neuroscience gathered at the University of Cambridge to celebrate the Francis Crick Memorial Conference, which deals with consciousness in humans and pre-linguistic consciousness in nonhuman animals. After the conference, they signed in the presence of Stephen Hawking, the 'Cambridge Declaration on Consciousness', which summarizes the most important findings of the survey: "We decided to reach a consensus and make a statement directed to the public that is not scientific. It's obvious to everyone in this room that animals have consciousness, but it is not obvious to the rest of the world. It is not obvious to the rest of the Western world or the Far East. It is not obvious to the society." "Convergent evidence indicates that non-human animals ..., including all mammals and birds, and other creatures, ... have the necessary neural substrates of consciousness and the capacity to exhibit intentional behaviors."


Artifact consciousness

The idea of an wikt:artifact, artifact made conscious is an ancient theme of mythology, appearing for example in the Greek myth of Pygmalion (mythology), Pygmalion, who carved a statue that was magically brought to life, and in medieval Jewish stories of the Golem, a magically animated homunculus built of clay. However, the possibility of actually constructing a conscious machine was probably first discussed by Ada Lovelace, in a set of notes written in 1842 about the Analytical Engine invented by Charles Babbage, a precursor (never built) to modern electronic computers. Lovelace was essentially dismissive of the idea that a machine such as the Analytical Engine could think in a humanlike way. She wrote: One of the most influential contributions to this question was an essay written in 1950 by pioneering computer scientist Alan Turing, titled ''Computing Machinery and Intelligence''. Turing disavowed any interest in terminology, saying that even "Can machines think?" is too loaded with spurious connotations to be meaningful; but he proposed to replace all such questions with a specific operational test, which has become known as the Turing test. To pass the test, a computer must be able to imitate a human well enough to fool interrogators. In his essay Turing discussed a variety of possible objections, and presented a counterargument to each of them. The Turing test is commonly cited in discussions of
artificial intelligence Artificial intelligence (AI) is intelligence Intelligence has been defined in many ways: the capacity for abstraction Abstraction in its main sense is a conceptual process where general rules and concept Concepts are defined as abstra ...

artificial intelligence
as a proposed criterion for machine consciousness; it has provoked a great deal of philosophical debate. For example, Daniel Dennett and Douglas Hofstadter argue that anything capable of passing the Turing test is necessarily conscious, while
David Chalmers David John Chalmers (; born 20 April 1966) is an Australian Australians, colloquially referred to as "Aussies", are the citizens Citizenship is a relationship between an individual and a state to which the individual owes allegiance ...

David Chalmers
argues that a philosophical zombie could pass the test, yet fail to be conscious. A third group of scholars have argued that with technological growth once machines begin to display any substantial signs of human-like behavior then the dichotomy (of human consciousness compared to human-like consciousness) becomes passé and issues of machine autonomy begin to prevail even as observed in its nascent form within contemporary industry and technology. Jürgen Schmidhuber argues that consciousness is simply the result of compression. As an agent sees representation of itself recurring in the environment, the compression of this representation can be called consciousness. In a lively exchange over what has come to be referred to as "the Chinese room argument", John Searle sought to refute the claim of proponents of what he calls "strong artificial intelligence (AI)" that a computer program can be conscious, though he does agree with advocates of "weak AI" that computer programs can be formatted to "simulate" conscious states. His own view is that consciousness has subjective, first-person causal powers by being essentially intentional due simply to the way human brains function biologically; conscious persons can perform computations, but consciousness is not inherently computational the way computer programs are. To make a Turing machine that speaks Chinese, Searle imagines a room with one monolingual English speaker (Searle himself, in fact), a book that designates a combination of Chinese symbols to be output paired with Chinese symbol input, and boxes filled with Chinese symbols. In this case, the English speaker is acting as a computer and the rulebook as a program. Searle argues that with such a machine, he would be able to process the inputs to outputs perfectly without having any understanding of Chinese, nor having any idea what the questions and answers could possibly mean. If the experiment were done in English, since Searle knows English, he would be able to take questions and give answers without any algorithms for English questions, and he would be effectively aware of what was being said and the purposes it might serve. Searle would pass the Turing test of answering the questions in both languages, but he is only conscious of what he is doing when he speaks English. Another way of putting the argument is to say that computer programs can pass the Turing test for processing the syntax of a language, but that the syntax cannot lead to semantic meaning in the way strong AI advocates hoped. In the literature concerning artificial intelligence, Searle's essay has been second only to Turing's in the volume of debate it has generated. Searle himself was vague about what extra ingredients it would take to make a machine conscious: all he proposed was that what was needed was "causal powers" of the sort that the brain has and that computers lack. But other thinkers sympathetic to his basic argument have suggested that the necessary (though perhaps still not sufficient) extra conditions may include the ability to pass not just the verbal version of the Turing test, but the Robotics, robotic version, which requires Symbol grounding, grounding the robot's words in the robot's sensorimotor capacity to Categorization, categorize and interact with the things in the world that its words are about, Turing-indistinguishably from a real person. Turing-scale robotics is an empirical branch of research on embodied cognition and situated cognition. In 2014, Victor Argonov has suggested a non-Turing test for machine consciousness based on machine's ability to produce philosophical judgments. He argues that a deterministic machine must be regarded as conscious if it is able to produce judgments on all problematic properties of consciousness (such as qualia or binding) having no innate (preloaded) philosophical knowledge on these issues, no philosophical discussions while learning, and no informational models of other creatures in its memory (such models may implicitly or explicitly contain knowledge about these creatures' consciousness). However, this test can be used only to detect, but not refute the existence of consciousness. A positive result proves that machine is conscious but a negative result proves nothing. For example, absence of philosophical judgments may be caused by lack of the machine's intellect, not by absence of consciousness.


Scientific study

For many decades, consciousness as a research topic was avoided by the majority of mainstream scientists, because of a general feeling that a phenomenon defined in subjective terms could not properly be studied using objective experimental methods. In 1975 George Mandler published an influential psychological study which distinguished between slow, serial, and limited conscious processes and fast, parallel and extensive unconscious ones. The Science and Religion Forum 1984 annual conference, From Artificial Intelligence to Human Consciousness''' identified the nature of consciousness as a matter for investigation; Donald Michie was a keynote speaker. Starting in the 1980s, an expanding community of neuroscientists and psychologists have associated themselves with a field called ''Consciousness Studies'', giving rise to a stream of experimental work published in books, journals such as ''Consciousness and Cognition'', ''Frontiers in Consciousness Research'', ''Psyche (consciousness journal), Psyche'', and the ''Journal of Consciousness Studies'', along with regular conferences organized by groups such as the Association for the Scientific Study of Consciousness and the Society for Consciousness Studies. Modern medical and psychological investigations into consciousness are based on psychological experiments (including, for example, the investigation of Priming (psychology), priming effects using subliminal stimuli), and on case studies of alterations in consciousness produced by trauma, illness, or drugs. Broadly viewed, scientific approaches are based on two core concepts. The first identifies the content of consciousness with the experiences that are reported by human subjects; the second makes use of the concept of consciousness that has been developed by neurologists and other medical professionals who deal with patients whose behavior is impaired. In either case, the ultimate goals are to develop techniques for assessing consciousness objectively in humans as well as other animals, and to understand the neural and psychological mechanisms that underlie it.


Measurement

Experimental research on consciousness presents special difficulties, due to the lack of a universally accepted operational definition. In the majority of experiments that are specifically about consciousness, the subjects are human, and the criterion used is verbal report: in other words, subjects are asked to describe their experiences, and their descriptions are treated as observations of the contents of consciousness. For example, subjects who stare continuously at a Necker cube usually report that they experience it "flipping" between two 3D configurations, even though the stimulus itself remains the same. The objective is to understand the relationship between the conscious awareness of stimuli (as indicated by verbal report) and the effects the stimuli have on brain activity and behavior. In several paradigms, such as the technique of response priming, the behavior of subjects is clearly influenced by stimuli for which they report no awareness, and suitable experimental manipulations can lead to increasing priming effects despite decreasing prime identification (double dissociation). Verbal report is widely considered to be the most reliable indicator of consciousness, but it raises a number of issues. For one thing, if verbal reports are treated as observations, akin to observations in other branches of science, then the possibility arises that they may contain errors—but it is difficult to make sense of the idea that subjects could be wrong about their own experiences, and even more difficult to see how such an error could be detected. Daniel Dennett has argued for an approach he calls heterophenomenology, which means treating verbal reports as stories that may or may not be true, but his ideas about how to do this have not been widely adopted. Another issue with verbal report as a criterion is that it restricts the field of study to humans who have language: this approach cannot be used to study consciousness in other species, pre-linguistic children, or people with types of brain damage that impair language. As a third issue, philosophers who dispute the validity of the Turing test may feel that it is possible, at least in principle, for verbal report to be dissociated from consciousness entirely: a philosophical zombie may give detailed verbal reports of awareness in the absence of any genuine awareness. Although verbal report is in practice the "gold standard" for ascribing consciousness, it is not the only possible criterion. In medicine, consciousness is assessed as a combination of verbal behavior, arousal, brain activity and purposeful movement. The last three of these can be used as indicators of consciousness when verbal behavior is absent. The scientific literature regarding the neural bases of arousal and purposeful movement is very extensive. Their reliability as indicators of consciousness is disputed, however, due to numerous studies showing that alert human subjects can be induced to behave purposefully in a variety of ways in spite of reporting a complete lack of awareness. Studies of the neuroscience of free will have also shown that the experiences that people report when they behave purposefully sometimes do not correspond to their actual behaviors or to the patterns of electrical activity recorded from their brains. Another approach applies specifically to the study of
self-awareness In philosophy of self The philosophy of self is the study of the many conditions of identity Identity may refer to: Social sciences * Identity (social science), personhood or group affiliation in psychology and sociology Group expre ...
, that is, the ability to distinguish oneself from others. In the 1970s Gordon G. Gallup, Gordon Gallup developed an operational test for self-awareness, known as the mirror test. The test examines whether animals are able to differentiate between seeing themselves in a mirror versus seeing other animals. The classic example involves placing a spot of coloring on the skin or fur near the individual's forehead and seeing if they attempt to remove it or at least touch the spot, thus indicating that they recognize that the individual they are seeing in the mirror is themselves. Humans (older than 18 months) and other Hominidae, great apes, bottlenose dolphins, killer whales, Columbidae, pigeons, Eurasian magpie, European magpies and elephants have all been observed to pass this test.


Neural correlates

A major part of the scientific literature on consciousness consists of studies that examine the relationship between the experiences reported by subjects and the activity that simultaneously takes place in their brains—that is, studies of the neural correlates of consciousness. The hope is to find that activity in a particular part of the brain, or a particular pattern of global brain activity, which will be strongly predictive of conscious awareness. Several brain imaging techniques, such as EEG and fMRI, have been used for physical measures of brain activity in these studies. Another idea that has drawn attention for several decades is that consciousness is associated with high-frequency (gamma band) neural oscillations, oscillations in brain activity. This idea arose from proposals in the 1980s, by Christof von der Malsburg and Wolf Singer, that gamma oscillations could solve the so-called binding problem, by linking information represented in different parts of the brain into a unified experience. Rodolfo Llinás, for example, proposed that consciousness results from recurrent thalamo-cortical resonance where the specific thalamocortical systems (content) and the non-specific (centromedial thalamus) thalamocortical systems (context) interact in the gamma wave, gamma band frequency via synchronous oscillations. A number of studies have shown that activity in primary sensory areas of the brain is not sufficient to produce consciousness: it is possible for subjects to report a lack of awareness even when areas such as the primary visual cortex, primary visual cortex (V1) show clear electrical responses to a stimulus. Higher brain areas are seen as more promising, especially the prefrontal cortex, which is involved in a range of higher cognitive functions collectively known as executive functions. There is substantial evidence that a "top-down" flow of neural activity (i.e., activity propagating from the frontal cortex to sensory areas) is more predictive of conscious awareness than a "bottom-up" flow of activity. The prefrontal cortex is not the only candidate area, however: studies by Nikos Logothetis and his colleagues have shown, for example, that visually responsive neurons in parts of the temporal lobe reflect the visual perception in the situation when conflicting visual images are presented to different eyes (i.e., bistable percepts during binocular rivalry). Furthermore, top-down feedback from higher to lower visual brain areas may be weaker or absent in the peripheral visual field, as suggested by some experimental data and theoretical arguments; nevertheless humans can perceive visual inputs in the peripheral visual field arising from bottom-up V1 neural activities. Meanwhile, bottom-up V1 activities for the central visual fields can be vetoed, and thus made invisible to perception, by the top-down feedback, when these bottom-up signals are inconsistent with brain's internal model of the visual world. Modulation of neural responses may correlate with phenomenal experiences. In contrast to the raw electrical responses that do not correlate with consciousness, the modulation of these responses by other stimuli correlates surprisingly well with an important aspect of consciousness: namely with the phenomenal experience of stimulus intensity (brightness, contrast). In the research group of Danko Nikolić it has been shown that some of the changes in the subjectively perceived brightness correlated with the modulation of firing rates while others correlated with the modulation of neural synchrony. An fMRI investigation suggested that these findings were strictly limited to the primary visual areas. This indicates that, in the primary visual areas, changes in firing rates and synchrony can be considered as neural correlates of qualia—at least for some type of qualia. In 2011, Michael Graziano, Graziano and Kastner proposed the attention schema theory, "attention schema" theory of awareness. In that theory, specific cortical areas, notably in the superior temporal sulcus and the temporo-parietal junction, are used to build the construct of awareness and attribute it to other people. The same cortical machinery is also used to attribute awareness to oneself. Damage to these cortical regions can lead to deficits in consciousness such as hemispatial neglect. In the attention schema theory, the value of explaining the feature of awareness and attributing it to a person is to gain a useful predictive model of that person's attentional processing. Attention is a style of information processing in which a brain focuses its resources on a limited set of interrelated signals. Awareness, in this theory, is a useful, simplified schema that represents attentional states. To be aware of X is explained by constructing a model of one's attentional focus on X. In 2013, the perturbational complexity index (PCI) was proposed, a measure of the algorithmic complexity of the electrophysiological response of the cortex to transcranial magnetic stimulation. This measure was shown to be higher in individuals that are awake, in REM sleep or in a locked-in state than in those who are in deep sleep or in a vegetative state, making it potentially useful as a quantitative assessment of consciousness states. Assuming that not only humans but even some non-mammalian species are conscious, a number of evolutionary approaches to the problem of neural correlates of consciousness open up. For example, assuming that birds are conscious—a common assumption among neuroscientists and ethologists due to the extensive cognitive repertoire of birds—there are comparative neuroanatomical ways to validate some of the principal, currently competing, mammalian consciousness–brain theories. The rationale for such a comparative study is that the avian brain deviates structurally from the mammalian brain. So how similar are they? What homologues can be identified? The general conclusion from the study by Butler, et al., is that some of the major theories for the mammalian brain also appear to be valid for the avian brain. The structures assumed to be critical for consciousness in mammalian brains have homologous counterparts in avian brains. Thus the main portions of the theories of Francis Crick, Crick and Christof Koch, Koch, Edelman and Giulio Tononi, Tononi, and Cotterill seem to be compatible with the assumption that birds are conscious. Edelman also differentiates between what he calls primary consciousness (which is a trait shared by humans and non-human animals) and higher-order consciousness as it appears in humans alone along with human language capacity. Certain aspects of the three theories, however, seem less easy to apply to the hypothesis of avian consciousness. For instance, the suggestion by Crick and Koch that layer 5 neurons of the mammalian brain have a special role, seems difficult to apply to the avian brain, since the avian homologues have a different morphology. Likewise, the theory of John Eccles (neurophysiologist), Eccles seems incompatible, since a structural homologue/analogue to the dendron has not been found in avian brains. The assumption of an avian consciousness also brings the reptilian brain into focus. The reason is the structural continuity between avian and reptilian brains, meaning that the phylogenetic origin of consciousness may be earlier than suggested by many leading neuroscientists. Joaquin Fuster of UCLA has advocated the position of the importance of the prefrontal cortex in humans, along with the areas of Wernicke and Broca, as being of particular importance to the development of human language capacities neuro-anatomically necessary for the emergence of higher-order consciousness in humans.


Biological function and evolution

Opinions are divided as to where in biological evolution consciousness emerged and about whether or not consciousness has any survival value. Some argue that consciousness is a byproduct of evolution. It has been argued that consciousness emerged (i) exclusively with the first humans, (ii) exclusively with the first mammals, (iii) independently in mammals and birds, or (iv) with the first reptiles. Other authors date the origins of consciousness to the first animals with nervous systems or early vertebrates in the Cambrian over 500 million years ago. Donald Griffin suggests in his book ''Animal Minds'' a gradual evolution of consciousness. Each of these scenarios raises the question of the possible survival value of consciousness. Thomas Henry Huxley defends in an essay titled ''On the Hypothesis that Animals are Automaton, Automata, and its History'' an epiphenomenalism, epiphenomenalist theory of consciousness according to which consciousness is a causally inert effect of neural activity—"as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery". To this William James objects in his essay ''Are We Automata?'' by stating an evolutionary argument for mind-brain interaction implying that if the preservation and development of consciousness in the biological evolution is a result of natural selection, it is plausible that consciousness has not only been influenced by neural processes, but has had a survival value itself; and it could only have had this if it had been efficacious. Karl Popper develops in the book ''The Self and Its Brain'' a similar evolutionary argument. Regarding the primary function of conscious processing, a recurring idea in recent theories is that phenomenal states somehow integrate neural activities and information-processing that would otherwise be independent. This has been called the ''integration consensus''. Another example has been proposed by Gerald Edelman called dynamic core hypothesis which puts emphasis on reentry (neural circuitry), reentrant connections that reciprocally link areas of the brain in a massively parallel manner. Edelman also stresses the importance of the evolutionary emergence of higher-order consciousness in humans from the historically older trait of primary consciousness which humans share with non-human animals (see ''#Neural correlates, Neural correlates'' section above). These theories of integrative function present solutions to two classic problems associated with consciousness: differentiation and unity. They show how our conscious experience can discriminate between a virtually unlimited number of different possible scenes and details (differentiation) because it integrates those details from our sensory systems, while the integrative nature of consciousness in this view easily explains how our experience can seem unified as one whole despite all of these individual parts. However, it remains unspecified which kinds of information are integrated in a conscious manner and which kinds can be integrated without consciousness. Nor is it explained what specific causal role conscious integration plays, nor why the same functionality cannot be achieved without consciousness. Obviously not all kinds of information are capable of being disseminated consciously (e.g., neural activity related to vegetative functions, reflexes, unconscious motor programs, low-level perceptual analyses, etc.) and many kinds of information can be disseminated and combined with other kinds without consciousness, as in intersensory interactions such as the ventriloquism effect. Hence it remains unclear why any of it is conscious. For a review of the differences between conscious and unconscious integrations, see the article of E. Morsella. As noted earlier, even among writers who consider consciousness to be a well-defined thing, there is Animal consciousness, widespread dispute about which animals other than humans can be said to possess it. Edelman has described this distinction as that of humans possessing higher-order consciousness while sharing the trait of primary consciousness with non-human animals (see previous paragraph). Thus, any examination of the evolution of consciousness is faced with great difficulties. Nevertheless, some writers have argued that consciousness can be viewed from the standpoint of evolutionary biology as an adaptation in the sense of a Phenotypic trait, trait that increases Fitness (biology), fitness. In his article "Evolution of consciousness", John Eccles argued that special anatomical and physical properties of the mammalian cerebral cortex gave rise to consciousness ("[a] psychon ... linked to [a] dendron through quantum physics"). Bernard Baars proposed that once in place, this "recursive" circuitry may have provided a basis for the subsequent development of many of the functions that consciousness facilitates in higher organisms. Peter Carruthers (philosopher), Peter Carruthers has put forth one such potential adaptive advantage gained by conscious creatures by suggesting that consciousness allows an individual to make distinctions between appearance and reality. This ability would enable a creature to recognize the likelihood that their perceptions are deceiving them (e.g. that water in the distance may be a mirage) and behave accordingly, and it could also facilitate the manipulation of others by recognizing how things appear to them for both cooperative and devious ends. Other philosophers, however, have suggested that consciousness would not be necessary for any functional advantage in evolutionary processes. No one has given a causal explanation, they argue, of why it would not be possible for a functionally equivalent non-conscious organism (i.e., a philosophical zombie) to achieve the very same survival advantages as a conscious organism. If evolutionary processes are blind to the difference between function ''F'' being performed by conscious organism ''O'' and non-conscious organism ''O*'', it is unclear what adaptive advantage consciousness could provide. As a result, an exaptive explanation of consciousness has gained favor with some theorists that posit consciousness did not evolve as an adaptation but was an exaptation arising as a consequence of other developments such as increases in brain size or cortical rearrangement. Consciousness in this sense has been compared to the blind spot in the retina where it is not an adaption of the retina, but instead just a by-product of the way the retinal axons were wired. Several scholars including Pinker, Chomsky, Edelman, and Luria have indicated the importance of the emergence of human language as an important regulative mechanism of learning and memory in the context of the development of higher-order consciousness (see ''#Neural correlates, Neural correlates'' section above). Another idea suggested where consciousness originates from a cell that has nestled itself in a blood capillary in the brain where the blood flow determines whether or not one is conscious.


States of consciousness

There are some brain states in which consciousness seems to be absent, including dreamless sleep or coma. There are also a variety of circumstances that can change the relationship between the mind and the world in less drastic ways, producing what are known as
altered states of consciousness An altered state of consciousness (ASC), also called altered state of mind or mind alteration, is any condition which is significantly different from a normal waking state. By 1892, the expression was in use in relation to hypnosis File: ...
. Some altered states occur naturally; others can be produced by drugs or brain damage. Altered states can be accompanied by changes in thinking, disturbances in the sense of time, feelings of loss of control, changes in emotional expression, alternations in body image and changes in meaning or significance. The two most widely accepted altered states are sleep and dreaming. Although dream sleep and non-dream sleep appear very similar to an outside observer, each is associated with a distinct pattern of brain activity, metabolic activity, and eye movement; each is also associated with a distinct pattern of experience and cognition. During ordinary non-dream sleep, people who are awakened report only vague and sketchy thoughts, and their experiences do not cohere into a continuous narrative. During dream sleep, in contrast, people who are awakened report rich and detailed experiences in which events form a continuous progression, which may however be interrupted by bizarre or fantastic intrusions. Thought processes during the dream state frequently show a high level of irrationality. Both dream and non-dream states are associated with severe disruption of memory: it usually disappears in seconds during the non-dream state, and in minutes after awakening from a dream unless actively refreshed. Research conducted on the effects of partial epileptic seizures on consciousness found that patients who have partial epileptic seizures experience altered states of consciousness. In partial epileptic seizures, consciousness is impaired or lost while some aspects of consciousness, often automated behaviors, remain intact. Studies found that when measuring the qualitative features during partial epileptic seizures, patients exhibited an increase in arousal and became absorbed in the experience of the seizure, followed by difficulty in focusing and shifting attention. A variety of psychoactive drugs, including Ethanol, alcohol, have notable effects on consciousness. These range from a simple dulling of awareness produced by sedatives, to increases in the intensity of sensory qualities produced by stimulants, cannabis (drug), cannabis, empathogen-entactogen, empathogens–entactogens such as MDMA ("Ecstasy"), or most notably by the class of drugs known as psychedelic drug, psychedelics. Lysergic acid diethylamide, LSD, mescaline, psilocybin, N,N-Dimethyltryptamine, dimethyltryptamine, and others in this group can produce major distortions of perception, including hallucinations; some users even describe their drug-induced experiences as mystical or spiritual in quality. The brain mechanisms underlying these effects are not as well understood as those induced by use of alcohol, but there is substantial evidence that alterations in the brain system that uses the chemical neurotransmitter serotonin play an essential role. There has been some research into physiological changes in yogis and people who practise various techniques of meditation. Some research with brain waves during meditation has reported differences between those corresponding to ordinary relaxation and those corresponding to meditation. It has been disputed, however, whether there is enough evidence to count these as physiologically distinct states of consciousness. The most extensive study of the characteristics of altered states of consciousness was made by psychologist Charles Tart in the 1960s and 1970s. Tart analyzed a state of consciousness as made up of a number of component processes, including exteroception (sensing the external world); interoception (sensing the body); input-processing (seeing meaning); emotions; memory; time sense; sense of identity; evaluation and cognitive processing; motor output; and interaction with the environment. Each of these, in his view, could be altered in multiple ways by drugs or other manipulations. The components that Tart identified have not, however, been validated by empirical studies. Research in this area has not yet reached firm conclusions, but a recent questionnaire-based study identified eleven significant factors contributing to drug-induced states of consciousness: experience of unity; spiritual experience; blissful state; insightfulness; disembodiment; impaired control and cognition; anxiety; complex imagery; elementary imagery; audio-visual synesthesia; and changed meaning of percepts.


Phenomenology

Phenomenology is a method of inquiry that attempts to examine the structure of consciousness in its own right, putting aside problems regarding the relationship of consciousness to the physical world. This approach was first proposed by the philosopher Edmund Husserl, and later elaborated by other philosophers and scientists. Husserl's original concept gave rise to two distinct lines of inquiry, in philosophy and psychology. phenomenology (philosophy), In philosophy, phenomenology has largely been devoted to fundamental metaphysical questions, such as the nature of intentionality (''"aboutness"''). phenomenology (psychology), In psychology, phenomenology largely has meant attempting to investigate consciousness using the method of
introspection Introspection is the examination of one's own conscious , an English Paracelsian Paracelsianism (also Paracelsism; German: ') was an early modern History of medicine, medical movement based on the theories and therapies of Paracelsus. It de ...
, which means looking into one's own mind and reporting what one observes. This method fell into disrepute in the early twentieth century because of grave doubts about its reliability, but has been rehabilitated to some degree, especially when used in combination with techniques for examining brain activity. Introspectively, the world of conscious experience seems to have considerable structure. Immanuel Kant asserted that the world as we perceive it is organized according to a set of fundamental "intuitions", which include 'object' (we perceive the world as a set of distinct things); 'shape'; 'quality' (color, warmth, etc.); 'space' (distance, direction, and location); and 'time'. Some of these constructs, such as space and time, correspond to the way the world is structured by the laws of physics; for others, the correspondence is not as clear. Understanding the physical basis of qualities, such as redness or pain, has been particularly challenging. David Chalmers has called this the hard problem of consciousness. Some philosophers have argued that it is intrinsically unsolvable, because qualities ("''
qualia In philosophy of mind Philosophy of mind is a branch of that studies the and nature of the and its relationship with the body. The is a paradigmatic issue in philosophy of mind, although a number of other issues are addressed, such as the ...
''") are ineffability, ineffable; that is, they are "raw feels", incapable of being analyzed into component processes. Other psychologists and neuroscientists reject these arguments. For example, research on ideasthesia shows that qualia are organised into a semantic-like network. Nevertheless, it is clear that the relationship between a physical entity such as light and a perceptual quality such as color is extraordinarily complex and indirect, as demonstrated by a variety of optical illusions such as neon color spreading. In neuroscience, a great deal of effort has gone into investigating how the perceived world of conscious awareness is constructed inside the brain. The process is generally thought to involve two primary mechanisms: hierarchical processing of sensory inputs, and memory. Signals arising from sensory organs are transmitted to the brain and then processed in a series of stages, which extract multiple types of information from the raw input. In the visual system, for example, sensory signals from the eyes are transmitted to the thalamus and then to the primary visual cortex; inside the cerebral cortex they are sent to areas that extract features such as three-dimensional structure, shape, color, and motion. Memory comes into play in at least two ways. First, it allows sensory information to be evaluated in the context of previous experience. Second, and even more importantly, working memory allows information to be integrated over time so that it can generate a stable representation of the world—Gerald Edelman expressed this point vividly by titling one of his books about consciousness ''The Remembered Present''. In computational neuroscience, Bayesian approaches to brain function have been used to understand both the evaluation of sensory information in light of previous experience, and the integration of information over time. Bayesian models of the brain are probabilistic inference models, in which the brain takes advantage of prior knowledge to interpret uncertain sensory inputs in order to formulate a conscious percept; Bayesian models have successfully predicted many perceptual phenomena in vision and the nonvisual senses. Despite the large amount of information available, many important aspects of perception remain mysterious. A great deal is known about low-level signal processing in sensory systems. However, how sensory systems, action systems, and language systems interact are poorly understood. At a deeper level, there are still basic conceptual issues that remain unresolved. Many scientists have found it difficult to reconcile the fact that information is distributed across multiple brain areas with the apparent unity of consciousness: this is one aspect of the so-called binding problem. There are also some scientists who have expressed grave reservations about the idea that the brain forms representations of the outside world at all: influential members of this group include psychologist James J. Gibson, J. J. Gibson and roboticist Rodney Brooks, who both argued in favor of "intelligence without representation".


Entropic brain

The entropic brain is a theory of conscious states informed by neuroimaging research with psychedelic drugs. The theory suggests that the brain in primary states such as Rapid eye movement sleep, rapid eye movement (REM) sleep, early psychosis and under the influence of psychedelic drugs, is in a disordered state; normal waking consciousness constrains some of this freedom and makes possible metacognitive functions such as internal self-administered reality testing and
self-awareness In philosophy of self The philosophy of self is the study of the many conditions of identity Identity may refer to: Social sciences * Identity (social science), personhood or group affiliation in psychology and sociology Group expre ...
. Criticism has included questioning whether the theory has been adequately tested.


Medical aspects

The medical approach to consciousness is practically oriented. It derives from a need to treat people whose brain function has been impaired as a result of disease, brain damage, toxins, or drugs. In medicine, conceptual distinctions are considered useful to the degree that they can help to guide treatments. Whereas the philosophical approach to consciousness focuses on its fundamental nature and its contents, the medical approach focuses on the amount of consciousness a person has: in medicine, consciousness is assessed as a "level" ranging from coma and brain death at the low end, to full alertness and purposeful responsiveness at the high end. Consciousness is of concern to patients and physicians, especially neurology, neurologists and anesthesia, anesthesiologists. Patients may have disorders of consciousness or may need to be anesthetized for a surgical procedure. Physicians may perform consciousness-related interventions such as instructing the patient to sleep, administering general anesthesia, or inducing induced coma, medical coma. Also, bioethics, bioethicists may be concerned with the ethical implications of consciousness in medical cases of patients such as the Karen Ann Quinlan case, while neuroscientists may study patients with impaired consciousness in hopes of gaining information about how the brain works.


Assessment

In medicine, consciousness is examined using a set of procedures known as neuropsychological assessment. There are two commonly used methods for assessing the level of consciousness of a patient: a simple procedure that requires minimal training, and a more complex procedure that requires substantial expertise. The simple procedure begins by asking whether the patient is able to move and react to physical stimuli. If so, the next question is whether the patient can respond in a meaningful way to questions and commands. If so, the patient is asked for name, current location, and current day and time. A patient who can answer all of these questions is said to be "alert and oriented times four" (sometimes denoted "A&Ox4" on a medical chart), and is usually considered fully conscious. The more complex procedure is known as a neurological examination, and is usually carried out by a neurology, neurologist in a hospital setting. A formal neurological examination runs through a precisely delineated series of tests, beginning with tests for basic sensorimotor reflexes, and culminating with tests for sophisticated use of language. The outcome may be summarized using the
Glasgow Coma Scale The Glasgow Coma Scale (GCS) is a clinical scale used to reliably measure a person's level of consciousness after a brain injury. The GCS assesses a person based on their ability to perform eye movements, speak, and move their body. These thre ...
, which yields a number in the range 3–15, with a score of 3 to 8 indicating coma, and 15 indicating full consciousness. The Glasgow Coma Scale has three subscales, measuring the best motor response (ranging from "no motor response" to "obeys commands"), the best eye response (ranging from "no eye opening" to "eyes opening spontaneously") and the best verbal response (ranging from "no verbal response" to "fully oriented"). There is also a simpler Paediatric Glasgow Coma Scale, pediatric version of the scale, for children too young to be able to use language. In 2013, an experimental procedure was developed to measure degrees of consciousness, the procedure involving stimulating the brain with a magnetic pulse, measuring resulting waves of electrical activity, and developing a consciousness score based on the complexity of the brain activity.


Disorders of consciousness

Medical conditions that inhibit consciousness are considered disorders of consciousness. This category generally includes minimally conscious state and persistent vegetative state, but sometimes also includes the less severe locked-in syndrome and more severe coma, chronic coma. Differential diagnosis of these disorders is an active area of biomedical research. Finally, brain death results in possible irreversible disruption of consciousness. While other conditions may cause a moderate deterioration (e.g., dementia and
delirium Delirium (also known as acute confusional state) is an organically caused decline from a previous baseline mental functioning, that develops over a short period of time, typically hours to days. Delirium is a syndrome A syndrome is a set of me ...
) or transient interruption (e.g., tonic–clonic seizure, grand mal and absence seizure, petit mal seizures) of consciousness, they are not included in this category.


Anosognosia

One of the most striking disorders of consciousness goes by the name anosognosia, a Greek-derived term meaning 'unawareness of disease'. This is a condition in which patients are disabled in some way, most commonly as a result of a stroke, but either misunderstand the nature of the problem or deny that there is anything wrong with them. The most frequently occurring form is seen in people who have experienced a stroke damaging the parietal lobe in the right hemisphere of the brain, giving rise to a syndrome known as hemispatial neglect, characterized by an inability to direct action or attention toward objects located to the left with respect to their bodies. Patients with hemispatial neglect are often paralyzed on the right side of the body, but sometimes deny being unable to move. When questioned about the obvious problem, the patient may avoid giving a direct answer, or may give an explanation that doesn't make sense. Patients with hemispatial neglect may also fail to recognize paralyzed parts of their bodies: one frequently mentioned case is of a man who repeatedly tried to throw his own paralyzed right leg out of the bed he was lying in, and when asked what he was doing, complained that somebody had put a dead leg into the bed with him. An even more striking type of anosognosia is Anton–Babinski syndrome, a rarely occurring condition in which patients become blind but claim to be able to see normally, and persist in this claim in spite of all evidence to the contrary.


Stream of consciousness

William James is usually credited with popularizing the idea that human consciousness flows like a stream, in his ''Principles of Psychology'' of 1890. According to James, the "stream of thought" is governed by five characteristics: # ''Every thought tends to be part of a personal consciousness.'' # ''Within each personal consciousness thought is always changing.'' # ''Within each personal consciousness thought is sensibly continuous.'' # ''It always appears to deal with objects independent of itself.'' # ''It is interested in some parts of these objects to the exclusion of others". A similar concept appears in Buddhist philosophy, expressed by the Sanskrit term ''Citta-saṃtāna'', which is usually translated as mindstream or "mental continuum". Buddhist teachings describe that consciousness manifests moment to moment as sense impressions and mental phenomena that are continuously changing. The teachings list six triggers that can result in the generation of different mental events. These triggers are input from the five senses (seeing, hearing, smelling, tasting or touch sensations), or a thought (relating to the past, present or the future) that happen to arise in the mind. The mental events generated as a result of these triggers are: feelings, perceptions and intentions/behaviour. The moment-by-moment manifestation of the mind-stream is said to happen in every person all the time. It even happens in a scientist who analyses various phenomena in the world, or analyses the material body including the organ brain. The manifestation of the mindstream is also described as being influenced by physical laws, biological laws, psychological laws, volitional laws, and universal laws. The purpose of the Buddhist practice of mindfulness is to understand the inherent nature of the consciousness and its characteristics.


Narrative form

In the West, the primary impact of the idea has been on literature rather than science: "stream of consciousness (narrative mode), stream of consciousness as a narrative mode" means writing in a way that attempts to portray the moment-to-moment thoughts and experiences of a character. This technique perhaps had its beginnings in the monologues of Shakespeare's plays and reached its fullest development in the novels of James Joyce and Virginia Woolf, although it has also been used by many other noted writers. Here, for example, is a passage from Joyce's ''Ulysses (novel), Ulysses'' about the thoughts of Molly Bloom:


Spiritual approaches

To most philosophers, the word "consciousness" connotes the relationship between the mind and the world. To writers on spiritual or religious topics, it frequently connotes the relationship between the mind and God, or the relationship between the mind and deeper truths that are thought to be more fundamental than the physical world. The mystical psychiatrist Richard Maurice Bucke, author of the 1901 book ''Cosmic Consciousness, Cosmic Consciousness: A Study in the Evolution of the Human Mind'', distinguished between three types of consciousness: 'Simple Consciousness', awareness of the body, possessed by many animals; 'Self Consciousness', awareness of being aware, possessed only by humans; and 'Cosmic Consciousness', awareness of the life and order of the universe, possessed only by humans who are enlightened. Many more examples could be given, such as the various levels of spiritual consciousness presented by Prem Saran Satsangi and Stuart Hameroff. Another thorough account of the spiritual approach is Ken Wilber's 1977 book ''The Spectrum of Consciousness'', a comparison of western and eastern ways of thinking about the mind. Wilber described consciousness as a spectrum with ordinary awareness at one end, and more profound types of awareness at higher levels.


See also

* Antahkarana * Centipede's dilemma * Cognitive closure (philosophy), Cognitive closure * Cognitive neuroscience * Cognitive psychology * Chaitanya (consciousness) * Episodic memory * Explanatory gap * Feelings * Functionalism (philosophy of mind) * Indian psychology * Merkwelt * Mirror neuron * Models of Consciousness * Modularity of mind * New mysterianism * Plant perception (paranormal) * Sakshi (Witness) * Solipsism


References


Further reading

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External links

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