Consciousness
Consciousness is an umbrella term that has
been used to refer to a variety of aspects of the relationship between the mind
and the world with which it interacts.[1]
It has been defined, at one time or another, as: subjective experience; awareness; the ability to
experience feelings;
wakefulness; having a sense of selfhood; or as the executive control system of the mind.[2]
Despite the difficulty of definition, many philosophers believe that there is a
basic underlying intuition about consciousness that is shared by nearly all
people.[3] As Max Velmans
and Susan Schneider wrote in The
Blackwell Companion to Consciousness:
"Anything that we are aware of at a given moment forms
part of our consciousness, making conscious experience at once the most
familiar and most mysterious aspect of our lives."[4]
In
philosophy, consciousness
is often said to imply four characteristics: subjectivity, change, continuity,
and selectivity.[2][5]
Philosopher Franz
Brentano has also suggested intentionality or aboutness (that consciousness is about something); however,
there is no consensus on whether intentionality is a requirement for
consciousness.[6]
Issues of practical concern in the philosophy of consciousness include whether
consciousness can ever be explained mechanistically; whether non-human
consciousness exists and if so how it can be recognized; at what point in fetal
development consciousness begins; and whether it may ever be possible for computers to
achieve a conscious state.[7][8][9]
At
one time consciousness was viewed with skepticism by many scientists and
considered within the domain of philosophers and theologians, but in recent
years it has been an increasingly significant research topic for psychology, neuroscience, and medicine.
In
psychology and neuroscience, the focus is
on understanding what it means biologically and psychologically for information
to be present in consciousness—that is, on determining the neural and
psychological correlates of consciousness. The majority of
experimental studies use human subjects and assess consciousness 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, blindsight,
denial of
impairment, and altered states of consciousness
produced by psychoactive drugs or spiritual or meditative techniques.
In
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, then delirium, then loss of any meaningful communication, and
ending with loss of movement in response to painful stimuli.[10]
Issues of practical concern include how the presence of consciousness can be
assessed in severely ill, comatose, or anesthetized people.[11]
The
origin of the modern concept of consciousness is often attributed to John Locke's Essay Concerning Human
Understanding, published in 1690.[12]
Locke explicitly defined consciousness as “the perception of what passes in a
man’s own mind.”[13]
His essay had much influence on the 18th century view of consciousness, and his
definition appeared in Samuel
Johnson's celebrated Dictionary (1755).
The
earliest English language uses of "conscious" and
"consciousness" date back, however, to the 1500s. The English word
"conscious" originally derived from Latin word conscius (con- "together" + scire "to
know"), but the Latin version did not have the same meaning as our word —
it meant knowing with, in other
words having joint or common knowledge
with another, privy to, cognizant of.[14]
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. Taken literally this is nonsense, but it 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 retained the Latin meaning. For
example Thomas Hobbes
in Leviathan 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 conscius sibi 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".[15]
A
related word was conscientia, which primarily means moral 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.[16]
Here, conscientia
is the knowledge that a witness has of the deed of someone else.[17] 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.[citation needed] Descartes
used "conscientia" the way modern speakers
would use "conscience." In Search
after Truth he says "conscience or internal testimony" (conscientia vel interno testimonio).[18]
Shortly
thereafter, in Britain, the neo-Platonist theologian Ralph Cudworth
used something resembling the modern meaning of consciousness in his "True
Intellectual System of the Universe" (1678), although he never
explicitly defined the term.[19]
There
are many philosophical stances on consciousness, including behaviorism, dualism, idealism, functionalism, reflexive monism, phenomenalism,
phenomenology and intentionality, physicalism,
emergentism,
mysticism, personal identity, and externalism. These stances
differ in the answers they give to a set of fundamental questions, including:
1.
Is consciousness a valid concept or a
conceptual error?
2.
Is consciousness a single unified
entity or a collection of disparate entities?
3.
How does consciousness relate to
language?
4.
How does consciousness relate to
behavior?
5.
Can consciousness be explained in terms
of the laws of physics?
6.
Why are we convinced that other people
(or even we ourselves) possess consciousness?
7.
Why do we believe that some animals
possess consciousness, and is there any way to test
this belief?
8.
What is the nature of experience, and
particularly what is the nature of sensory qualities such as the color red?
The
question about the relationship between consciousness and the physical realm is
perhaps the most contentious of all: several schools of thought are defined
mainly in terms of the answers they give to it.
A
majority of philosophers have felt that the word consciousness names a genuine
entity, but some who belong to the physicalist and behaviorist
schools have not been convinced; many scientists have also been dubious. The
most compelling argument in favor is that the vast majority of mankind has an
overwhelming intuition that there truly is such a thing. The argument against
is that this intuition, however compelling it may be, is false. Gilbert Ryle,
for example, argued that traditional understanding of consciousness depends on
a Cartesian dualist outlook that divides into mind and body, 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.[citation needed]
Another
problem that concerns many philosophers and scientists is the difficulty of
producing a definition that does not rely on circularity or fuzziness. The
neuroscientist Antonio Damasio, for example, calls consciousness "the
feeling of what happens", and defines it as "an organism's awareness
of its own self and its surroundings".[20]
These formulations seem intuitively reasonable, but they are difficult to apply
to specific situations.
Phenomenal
consciousness (P-consciousness) is simply experience;[21]
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.
The hard problem
of consciousness, formulated by David Chalmers in 1996,
deals with the issue of "how to explain a state of phenomenal
consciousness in terms of its neurological basis".[22]
Access consciousness
(A-consciousness) is the phenomenon whereby information in our minds is
accessible for verbal report, reasoning, and the control of behavior. So, when
we perceive,
information about what we perceive is often access conscious; when we introspect,
information about our thoughts is access conscious; when we remember,
information about the past (e.g., something that we learned) is
often access conscious, and so on. Chalmers thinks that access consciousness is
less mysterious than phenomenal consciousness, so that it is held to pose one
of the easy problems of
consciousness. Daniel
Dennett denies that there is a "hard problem", asserting that the
totality of consciousness can be understood in terms of impact on behavior, as
studied through heterophenomenology. There have been numerous
approaches to the processes that act on conscious experience from instant to
instant. Dennett suggests that what people think of as phenomenal
consciousness, such as qualia, are judgments and consequent behavior.[23]
He extends this analysis by arguing that phenomenal consciousness can be
explained in terms of access consciousness, denying the existence of qualia,
hence denying the existence of a "hard problem."[23]
Chalmers, on the other hand, argues that Dennett's explanatory processes merely
address aspects of the easy problem. Eccles and others have pointed out the
difficulty of explaining the evolution of qualia, or of 'minds', which
experience them, given that all the processes
governing evolution are physical and so have no direct access to them. There is
no guarantee that all people have minds, nor any way to verify whether one does
or does not possess one.
Events
that occur in the mind or brain that are not within phenomenal or access consciousness are known as subconscious events.
For
centuries, philosophers have investigated phenomenal consciousness. René Descartes, who
coined the famous dictum 'cogito
ergo sum', wrote Meditations
on First Philosophy in the seventeenth century.[24]
According to Descartes, all thought is conscious.[25]
Conscious experience, according to Descartes, included such ideas as imaginings
and perceptions
laid out in space and time that are viewed from a point,
and appearing as a result of some quality such as color, smell, and so on.
Descartes
defines ideas as extended
things, as in this excerpt from his Treatise
on Man:
Now among these figures, it is not
those imprinted on the external sense organs, or on the internal surface of the
brain, which should be taken to be ideas - but only those that are traced in
the spirits on the surface of gland H [where the seat of the imagination and
the 'common sense' is located]. That is to say, it is only the latter figures
which should be taken to be the forms or images which the rational soul united
to this machine will consider directly when it imagines some object or
perceives it by the senses.[26]
Thus
Descartes does not identify mental ideas with activity within the sense organs,
or even with brain activity, but rather with the "forms or images"
that unite the body and the "rational soul," through the mediating
'gland H'. This organ is now known as the pineal gland. Descartes
notes that, anatomically, while the human brain consists of two
symmetrical hemispheres the pineal gland, which lies close to the brain's
centre, appears to be singular. Thus he extrapolated from this that it was the
mediator between body and soul.[26]
Philosophical
responses, including those of Nicolas Malebranche, Thomas Reid, John Locke, David Hume and Immanuel Kant, were
varied. Malebranche, for example, agreed with
Descartes that the human being was composed of two elements, body and mind, and
that conscious experience resided in the latter. He did, however, disagree with
Descartes as to the ease with which we might become aware of our mental
constitution, stating 'I am not my own light unto myself'.[27]
David Hume and Immanuel Kant also differ from Descartes, in that they avoid
mentioning a place from which experience is viewed; certainly, few if any
modern philosophers have identified the pineal gland as the seat of dualist
interaction.
When
we look around a room or have a dream, things are laid out in space and time
and viewed as if from a point. However, when philosophers and scientists
consider the location of the form and contents of this phenomenal
consciousness, there are fierce disagreements. As an example, Descartes
proposed that the contents are brain activity seen by a non-physical place
without extension (the Res Cogitans),
which, in Meditations
on First Philosophy, he identified as the soul.[28]
This idea is known as Cartesian
Dualism. Another example is found in the work of Thomas Reid who thought the
contents of consciousness are the world itself, which becomes conscious
experience in some way. This concept is a type of Direct
realism. The precise physical substrate of conscious experience in the
world, such as photons, quantum fields, etc. is usually not specified.
Other
philosophers, such as George
Berkeley, have proposed that the contents of consciousness are an aspect of
minds and do not necessarily involve matter at all. This is a type of Idealism. Yet others, such as Leibniz, have
considered that each point in the universe is endowed with conscious content.
This is a form of Panpsychism, the belief that all matter, including
rocks for example, is sentient or conscious. The concept of the things in
conscious experience being impressions in the brain is a type of representationalism,
and representationalism is a form of indirect
realism.
It
is sometimes held that consciousness emerges from the complexity of brain
processing. The general label 'emergence'
applies to new phenomena that emerge from a physical basis without the
connection between the two explicitly specified.
Some
theorists hold that phenomenal consciousness poses an explanatory gap. Colin McGinn
takes the New Mysterianism position that it can't be solved, and
Chalmers criticizes purely physical accounts of mental
experiences based on the idea that philosophical zombies are logically possible
and supports property
dualism. But others have proposed speculative scientific theories to
explain the explanatory gap, such as Quantum mind, space-time
theories of consciousness,[29] reflexive monism, and Electromagnetic
theories of consciousness to explain the correspondence between brain
activity and experience.
Parapsychologists
and some philosophers e.g. Stephen Braude sometimes
appeal to the concepts of psychokinesis or telepathy to support the
belief that consciousness is not confined to the brain.
Because
humans express their conscious states using language, it is tempting to equate
language abilities and consciousness. There are, however, speechless humans
(infants, feral
children, aphasics,
severe forms of autism), to
whom consciousness is attributed despite language lost or not yet acquired.
Moreover, the study of brain states of non-linguistic primates, in particular
the macaques,
has been used extensively by scientists and philosophers in their quest for the
neural correlates of the contents of
consciousness.
Julian Jaynes
argued to the contrary, in The
Origin of Consciousness in the Breakdown of the Bicameral Mind, that
for consciousness to arise in a person, language needs to have reached a fairly
high level of complexity. According to Jaynes, human
consciousness emerged as recently as 1300 BCE or thereabouts. He defines
consciousness in such a way as to show how he conceives of it as a type of thinking
that builds upon non human ways of perceiving, for example (p. 55)...
Subjective conscious
mind is an analog of what is called the real world. It is built up like a
vocabulary or lexical field whose terms are all metaphors or analogs of
behavior in the physical world. Its reality is of the same order as
mathematics. It allows us to shortcut behavioral processes and arrive at more adequate decisions. Like mathematics, it is
an operator rather than a repository. And it is intimately bound up with volition
and decision.
...and
page 65...
It operates by way of
analogy, by way of constructing an analog space with an analog "I"
that can observe that space, and move metaphorically in it.
...and
perhaps most tellingly, page 66...
there
is nothing in consciousness that is not an analog of something that was in
behavior first.
Some
philosophers, including W.V. Quine, and some neuroscientists,
including Christof Koch, contest this hypothesis, arguing that it
suggests that prior to this "discovery" of consciousness, experience
simply did not exist.[30]
Ned Block argued that Jaynes had confused consciousness with the concept of consciousness,
the latter being what was discovered between the Iliad and the Odyssey.[31]
Daniel Dennett states
that these approaches misconceive Jaynes's definition
of consciousness as more than mere perception or awareness of an object. He
notes that consciousness is like money in that having the thing requires having
the concept of it, so it is a revolutionary proposal and not a ridiculous error
to suppose that consciousness only emerges when its concept does.
More
recently, Merlin Donald,
seeing a similar connection between language and consciousness, and a similar
link to cultural, and not purely genetic, evolution, has put a similar proposal
to Jaynes' forward - though relying on less specific
speculation about the more recent pre-history of consciousness. He writes...
To understand
consciousness fully, the generation of culture must be explained. Enculturation
has been neglected as a possible formative process in its own right, but we
have no alternative other than to give it pride of place in any evolutionary
theory.[32]
He
argues that an earlier "symbol using culture" must have preceded both
the personal symbol using of individual consciousness, as well as language itself.
The
idea that language and consciousness are not innate to humans, a characteristic
of human nature, but
rather the result of cultural evolution, beginning with something similar to
the culture of chimpanzees, goes back before
According
to Vedanta, awareness is
not a product of physical processes and can be considered under
four aspects. The first is waking consciousness (jagaritasthana), the
identification with “I” or “me” in relationship with phenomenal experiences
with external objects. The second aspect is dream consciousness (svapna-sthana),
which embodies the same subject/object duality as the waking state. The third
aspect of consciousness is deep sleep (susupti), which is non-dual as
a result of holding in abeyance all feelings, thoughts, and sensations. The
final aspect is the consciousness that underlies and transcends the first three
aspects (turiya)
also referred to as a trans-cognitive state (anubhava) or a state of
self-realization or freedom from body-mind identification (moksha).[33] Gaudiya Vedanta
recognizes a fifth aspect of consciousness in which God becomes subordinate to bhakti.[34]
In
Buddhism, consciousness (viññāṇa) is
included in the five classically defined experiential "aggregates".
The aggregates are seen as empty of self-nature; that is, they arise dependent on causes
and conditions. The cause for consciousness arising (viññāṇa)
is the arising of another aggregate (physical or mental); and, consciousness
arising in turn gives rise to one or more of the mental (nāma)
aggregates. The causation chain identified in the aggregate (khandha)
model overlaps the conditioning chain in Dependent Origination (paticcasamuppāda)
model. [35]
Consciousness is the third link, between mind
body mental formations and name & form in the traditional Twelve
Causes (nidāna)
of Dependent Origination.[36] The
six classes of consciousness are: eye-consciousness, ear-consciousness,
nose-consciousness, tongue-consciousness, body-consciousness, intellect-consciousness. [37]
The following aspects are traditionally highlighted within Dependent
Origination:
·
consciousness is conditioned by mental
fabrications (saṅkhāra);
·
consciousness and the mind-body (nāmarūpa)
are interdependent; and,
·
consciousness
acts as a "life force" by which there is a continuity across
rebirths.
Broadly
speaking, scientific approaches to consciousness can be divided into two
categories. In one category are methods that rely on asking subjects to describe
their experiences or answer questions, and therefore can only be conducted
using human subjects. In the other category are methods that test for aspects
of consciousness that can be manifested in nonverbal behavior, and therefore
can be used in other species as well as humans. The nonverbal manifestations
that have been used include arousal, responsiveness to stimulation, attention,
and the ability to distinguish self from non-self.
For
a long time in scientific psychology, consciousness as a research topic or
explanatory concept was strongly discouraged by mainstream scholars, because of
concerns about the validation of primary data .[38]
Research on topics associated with consciousness were
conducted under the banner of attention.
Modern investigations into consciousness are based on psychological statistical
studies and case studies of consciousness states and the deficits
caused by surgery, trauma or illness that disrupt the normal functioning of
human senses and cognition. Another approach is
experimental work on unconscious perception, e.g., the investigation of priming effects using subliminal stimuli.
These discoveries suggest that the mind
is a complex structure derived from various localized functions that are bound
together with a unitary awareness.[citation needed]
Several
studies point to common mechanisms in different clinical conditions that lead
to loss of consciousness. Persistent
vegetative state (PVS) is a condition in which an individual loses the
higher cerebral powers of the brain, but maintains sleep-wake cycles with full
or partial autonomic functions. Studies comparing PVS with healthy, awake
subjects consistently demonstrate an impaired connectivity between the deeper
(brainstem and thalamic) and the upper (cortical) areas of the brain. In
addition, it is agreed that the general brain activity in the cortex
is lower in the PVS state. Some electroneurobiological
interpretations of consciousness characterize this loss of consciousness as a
loss of the ability to resolve time (similar to playing an old phonographic
record at very slow or very rapid speed), along a continuum that starts with
inattention, continues on sleep, and arrives to coma and death .[39]
It is likely that different components of consciousness can be teased apart
with anesthetics,
sedatives and hypnotics.
These drugs appear to act differently on several brain areas to disrupt, to
varying degrees, different components of consciousness. The ability to recall
information, for example, may be disrupted by anesthetics acting on the hippocampal cortex. Neurons in this region are
particularly sensitive to anesthetics at the time loss of recall occurs. Direct
anesthetic actions on hippocampal neurons have been
shown to underlie EEG effects that occur in humans and animals during loss of
recall.[40]
Brain
chemistry affects human consciousness. Sleeping drugs
such as midazolam
(Dormicum) can bring the brain from the awake condition (conscious) to the sleep (unconscious)
condition. Wake-up drugs such as flumazenil
reverse this process. Many other drugs (such as alcohol, nicotine, Tetrahydrocannabinol
(THC), heroin, cocaine, LSD, MDMA, caffeine), have a
consciousness-changing effect.[citation needed]
Neurophysiological
studies in awake, behaving monkeys point to advanced cortical areas in
prefrontal cortex and temporal lobes as carriers of neuronal correlates of
consciousness. Christof Koch and Francis Crick argue that neuronal mechanisms of consciousness
are intricately related to prefrontal cortex — cortical areas involved in
higher cognitive function, affect, behavioral control, and planning. Rodolfo
Llinas proposes 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
band frequency via time coincidence. According to this view the "I"
represents a global predictive function required for intentionality.[41][42]
Experimental work of Steven Wise, Mikhail Lebedev
and their colleagues supports this view. They demonstrated that activity of
prefrontal cortex neurons reflects illusory perceptions of movements of visual
stimuli. Nikos Logothetis
and colleagues made similar observations on visually responsive neurons in the
temporal lobe. These neurons reflect the visual perception in the situation
when conflicting visual images are presented to different eyes (i.e., bistable percepts during binocular rivalry). The studies of
blindsight
— vision without awareness after lesions to parts of the visual system such as
the primary visual cortex — performed by Lawrence Weiskrantz
and David P. Carey provided important insights on how conscious perception
arises in the brain.[citation needed]
The
Neuroscience
of free will also seems to provide relevant insights to the understanding
of consciousness.
Experimental
research on consciousness presents special difficulties, e.g., when
establishing whether an observer is unaware of a critical stimulus. Several
techniques exist for dissociating the conscious visibility of stimuli from
indirect effects they might have on behavior.[43]
For example, the experimental technique of Response Priming allows
researchers to find conditions where the conscious visibility of a critical
stimulus and the ability of that stimulus to affect a motor response develop in
opposite directions, e.g., when motor effects of a stimulus become larger under
conditions where its visibility is decreasing.[44]
A
new approach has attempted to combine the methodologies of cognitive psychology
and traditional philosophy to understand consciousness. This research has taken
place in the new field called experimental
philosophy, which seeks to use empirical methods (like conducting
experiments to test how ordinary non-experts think) to inform the philosophical
discussion.[45]
The aim of this type of philosophical research on consciousness has been to try
to get a better grasp on how exactly people ordinarily understand
consciousness. For instance, work by Joshua Knobe and
Jesse Prinz suggests that people may have two
different ways of understanding minds generally.[46]
Another suggestion has been that there is actually no such phenomenon as
consciousness, based on a criticized study by Justin Sytsma
and Edouard Machery.[47]
Further, Justin Sytsma and Edouard
Machery have written about the proper methodology for
studying folk intuitions about consciousness.[48]
Consciousness
can be viewed from the standpoints of evolutionary
psychology or evolutionary biology
approach as an adaptation
because it is a trait that increases fitness.[49]
Consciousness also adheres to John Alcock's theory of animal behavioral adaptations because it
possesses both proximate and ultimate causes.[50]
In
his paper "Evolution of consciousness," John Eccles argues that
special anatomical and physical properties of the mammalian cerebral cortex gave
rise to consciousness.[51] Budiansky, by contrast, limits consciousness to humans,
proposing that human consciousness may have evolved as an adaptation to
anticipate and counter social strategems of other
humans, predators, and prey.[52]
Alternatively, it has been argued that the recursive circuitry underwriting
consciousness is much more primitive, having evolved initially in premammalian species because it improves the capacity for
interaction with both social and
natural environments by providing an energy-saving "neutral" gear in
an otherwise energy-expensive motor output machine.[53]
Another theory, proposed by Shaun
Nichols and Todd Grantham, proposes that it is unnecessary to trace the
exact evolutionary or causal role of phenomenal consciousness because the
complexity of phenomenal consciousness alone implies that it is an adaptation.[54]
Once in place, this recursive circuitry may well have provided a basis for the
subsequent development of many of the functions that consciousness facilitates
in higher organisms, as outlined by Bernard J. Baars.[55]
|
Functions of Consciousness |
|
|
Function |
Purpose |
|
Definition and context-setting |
Relating global input to its contexts,
thereby defining input and removing ambiguities |
|
Adaptation and learning |
Representing and adapting to novel
and significant events |
|
Editing, flagging, and debugging |
Monitoring conscious content, editing
it, and trying to change it if it is consciously "flagged" as an
error |
|
Recruiting and control function |
Recruiting subgoals
and motor systems to organize and carry out mental and physical actions |
|
Prioritizing and access control |
Control over what will become
conscious |
|
Decision-making or executive function |
Recruiting unconscious knowledge
sources to make proper decisions, and making goals conscious to allow
widespread recruitment of conscious and unconscious "votes" for or
against them |
|
Analogy-forming function |
Searching for a partial match between
contents of unconscious systems and a globally displayed (conscious) message |
|
Metacognitive
or self-forming function |
Reflection upon and control of our
own conscious and unconscious functioning |
|
Auto-programming and self-maintenance
function |
Maintenance of maximum stability in
the face of changing inner and outer conditions |
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 even consciousness could be explained in purely physical terms. The first
influential writer to propose such an idea explicitly was Julien Offray de La Mettrie, in his book Man a Machine (L'homme machine).[56]
The
most influential modern physical theories of consciousness are based on psychology and neuroscience. Theories
proposed by neuroscientists such as Gerald Edelman[57]
and António Damásio,[58]
and by philosophers such as Daniel Dennett,[59]
seek to explain access consciousness and phenomenal consciousness in terms of
neural events occurring within the brain. Many other neuroscientists, such as Christof
Koch,[60]
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 have pursued the
goal of creating digital computer programs that can simulate or embody consciousness.
Some
theorists—most of whom are physicists—have argued that classical physics is
intrinsically incapable of explaining the holistic aspects of consciousness,
but that quantum theory provides the
missing ingredients. The most notable theories falling into this category
include the Holonomic brain theory of Karl H. Pribram
and David Bohm,
and the 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 has been confirmed by experiment, and many scientists and
philosophers consider the arguments for an important role of quantum phenomena
to be unconvincing.[citation needed]
|
This section requires expansion. |
A
minimally conscious state (MCS) is a condition distinct from coma or the vegetative state,[61]
in which a patient exhibits deliberate, or cognitively
mediated, behavior[62]
often enough, or consistently enough, for clinicians to be able to distinguish
it from entirely unconscious, reflexive
responses.
A
persistent vegetative state is a condition of patients with severe brain damage who were in a
coma, but progressed to a state
of partial arousal rather than
true awareness. It is a diagnosis of some uncertainty in that it deals with a syndrome. After four weeks in
a vegetative state (VS), the patient is classified as in a persistent
vegetative state. This diagnosis is classified as a permanent vegetative state
(PVS) after approximately 1 year of being in a
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 (see review in Baars, 2002). This has been called the integration consensus. However, it
remained unspecified which kinds of information are integrated in a conscious
manner and which kinds can be integrated 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 can be
disseminated and combined with other kinds without consciousness, as in intersensory interactions such as the ventriloquism effect
(cf., Morsella, 2005).
Ervin László argues that self-awareness, the
ability to make observations of oneself, evolved. Émile
Durkheim formulated the concept of so called collective
consciousness, which is essential for organization of human, social
relations. The accelerating drive of human race to explorations, cognition,
understanding and technological progress can be explained by some features of collective
consciousness (collective self - concepts) and collective intelligence[citation needed]
As
there is no clear definition of consciousness and no empirical measure exists
to test for its presence, it has been argued that due to the nature of the
problem of consciousness, empirical tests are intrinsically impossible.
However, several tests have been developed that attempt an operational
definition of consciousness and try to determine whether computers and
non-human animals can demonstrate through behavior, by passing these tests, that
they are conscious.
In
medicine, several neurological and brain imaging techniques, such as EEG and fMRI,
have proven useful for physical measures of brain activity associated with
consciousness. This is particularly true for EEG measures during anesthesia,
which can provide an indication of anesthetic depth.
See also: Turing
test and philosophy
of artificial intelligence
Though
sometimes thought of as a test for consciousness, the Turing test (named after
computer scientist Alan
Turing, who proposed it) was originally presented as an operational
replacement for the question "Can machines think?",
which Turing regarded as too ambiguous to be meaningful. This test is commonly
cited in discussion of artificial
intelligence. The test is based on an "Imitation Game" in which a
human experimenter converses, via computer keyboards, with two competitors, one
human, the other a computer. Because all of the conversation is by keyboard, no
cues such as voice, prosody, or appearance will be available to indicate which
is human and which is the computer. If the human judge
is unable to determine which of the conversants is the computer, the computer is said to have
"passed" the test.
The
Turing test has generated 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,[63]
while David Chalmers,
argues that a philosophical
zombie could pass the test, yet fail to be conscious.[64]
It
has been argued that the question itself is excessively anthropomorphic. Edsger Dijkstra commented
that "The question of whether a computer can think is no more interesting
than the question of whether a submarine can swim", expressing the view
that different words are appropriate for the workings of a machine to those of
animals even if they produce similar results, just as submarines are not
normally said to swim.
Philosopher
John Searle developed a thought experiment,
the Chinese room
argument, which is intended to show problems with the Turing Test.[65]
Searle asks the reader to imagine a non-Chinese speaker in a room in which
there are stored a very large number of Chinese symbols and rule books. Questions are
passed to the person in the form of written Chinese symbols via a slot, and the
person responds by looking up the symbols and the correct replies in the rule
books. Based on the purely input-output operations, the "Chinese
room" gives the appearance of understanding Chinese. However, the person in
the room understands no Chinese at all. This argument has been the subject of
intense philosophical debate since it was introduced in 1980, even leading to
edited volumes on this topic alone.
The
application of the Turing test to human consciousness has even led to an annual
competition, the Loebner Prize[citation needed], with
"Grand Prize of $100,000 and a Gold Medal for the first computer whose
responses were indistinguishable from a human's."
Main article: Mirror test
See also the concept of the Mirror stage by Jacques Lacan
With
the mirror test, devised
by Gordon
Gallup in the 1970s, one is interested in whether animals are able to
recognize themselves in a mirror. The classic example of the test 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 great apes, bottlenose dolphins, pigeons, elephants[66]
and magpies[67]
have all been observed to pass this test. The test is usually carried out with
an identical 'spot' being placed elsewhere on the head with a non-visible
material as a control, to assure the subject is not responding to the touch
stimuli of the spot's presence.
One
problem researchers face is distinguishing nonconscious reflexes and instinctual responses from
conscious responses. Neuroscientists Francis Crick and Christof
Koch have proposed that by placing a delay between stimulus and execution
of action, one may determine the extent of involvement of consciousness in an
action of a biological organism.[citation needed]
For
example, when psychologists Larry
Squire and Robert Clark combined a tone of a specific pitch with a puff of
air to the eye, test subjects came to blink their eyes in anticipation of the
puff of air when the appropriate tone was played. When the puff of air followed
a half of a second later, no such conditioning occurred. When subjects were
asked about the experiment, only those who were asked to pay attention could
consciously distinguish which tone preceded the puff of air.[citation needed]
Ability
to delay the response to an action implies that the information must be stored
in short-term memory, which is conjectured to be a closely associated
prerequisite for consciousness. However, this test is only valid for biological
organisms. While it is simple to create a computer program that passes, such
success does not suggest anything beyond a clever programmer.[30][page needed]
The
merkwelt (German;
English:
"way of viewing the world", "peculiar individual
consciousness") is a concept in robotics, psychology and biology that describes a
creature or android's capacity to view things, manipulate information and synthesize
to make meaning out of the universe.[citation needed]
In
biology, a shark's merkwelt for instance is dominated by smell due to
its enlarged olfactory
lobes whilst a bat's is dominated by its hearing,
especially at ultrasonic frequencies. In literature, a character's merkwelt can be defined by their particular consciousness.
For the collective, the plural is merkwelten. It is
related to the original German meaning of zeitgeist and indeed a merkwelt can be thought of as a more general, individual
zeitgeist.[68][69][70]
To
have a merkwelt, the individual must be self-aware.
This "self-awareness"
may involve thoughts, sensations, perceptions, moods, emotions, and dreams.
This term was particularly developed by the German biologist Jakob
von Uexküll who framed it as part of his theory
of umwelt.
This basically stated that any living 'observer' of the broader environment or umwelt
through their particular werkwelt or 'mechanical
viewing' (that is to say, the organs through which they view the world- their
eyes, ears, mouth etc. in humans and electrical sensors in sharks for instance)
could have a merkwelt or 'perceptual universe'. In essence, his
theory posits that the way each human or certain type of aware animal perceives
of their environment both through their experiences, the particular way their
organs perceive their environment and the way in which their consciousness
processes this information (how their brain works).[clarification needed][71]
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"And what is consciousness? These six are classes
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Categories: Neuropsychology
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