LBNL-56279 : To Appear in Cambridge Handbook of Consciousness, Jan. 2007

**[Quantum Approaches to Consciousness.]{.underline}**

Henry P. Stapp

Theoretical Physics Group

Lawrence Berkeley National Laboratory

University of California

Berkeley, CA 94720

**\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--**

**This work was supported by the Director, Office of Science, Office of
High Energy and Nuclear Physics, of the U.S. Department of Energy under
contract DE-AC02-05CH11231**

**[1. Introduction.]{.underline}**

Quantum approaches to consciousness are sometimes said to be motivated
simply by the idea that quantum theory is a mystery and consciousness is
a mystery, so perhaps the two are related. That opinion betrays a
profound misunderstanding of the nature of quantum mechanics, which
consists fundamentally of a pragmatic scientific solution to the problem
of the connection between mind and matter.

The key philosophical and scientific achievement of the founders of
quantum theory was to forge a rationally coherent and practically useful
linkage between the two kinds of descriptions that jointly comprise the
foundation of science. Descriptions of the first kind are accounts of
psychologically experienced empirical findings, expressed in a language
that allows to us communicate to our colleagues what we have done and
what we have learned. Descriptions of the second kind are specifications
of physical properties, which are expressed by assigning mathematical
properties to space-time points, and formulating laws that determine how
these properties evolve over the course of time. Bohr, Heisenberg,
Pauli, and the other inventors of quantum theory discovered a useful way
to connect these two kinds of descriptions by causal laws, and their
seminal discovery was extended by John von Neumann from the domain of
atomic science to the realm of neuroscience, and in particular to the
problem of understanding and describing the causal connections between
the minds and the brains of human beings.

The magnitude of the difference between the quantum and classical
conceptions of the connection between mind and brain can scarcely be
exaggerated. All approaches to this problem based on the precepts of
classical physics founder first on the problem of the lack of any need
within classical mechanics for consciousness to exist at all, and second
on a conceptual gap that blocks any rational understanding of how the
experiential realities that form our streams of consciousness could ever
be produced by, or naturally come to be associated with, the motions of
the things that classical physics claims the physical world to be made
of. The first problem is that, according to precepts of classical
physics, the causal properties that it explicitly mentions suffice, by
themselves, with no acknowledgement of the existence of consciousness,
to completely specify all physical properties of the universe, including
the activities of our bodies and brains. According to the conceptual
structure of classical physics, everything physical would go on just the
same if nothing existed but the physical properties explicitly mentioned
in the theory. The second problem is that within that conceptual
framework of classical physics neither planets nor electrons, nor any of
the other entities, nor combinations of the entities that populate the
world *make* *choices on the basis of ideas*. The world described by the
concepts classical physics has been systematically stripped of, and is
consequently bereft of, the concept of choices based on consciously
experienced ideas. Thus the stubborn fact that idea-like realities do
exist enforces an awkward departure of science from a purely
naturalistic stance. Nonphysical features such as conscious thoughts,
ideas, and feelings must be added, for no apparent naturalistic,
physical, or rational reason, to the features that enter into the
putative laws of nature. There is thus a conceptual mismatch between the
world described by the basic laws of classical physics and the world we
inhabit and do science in.

These difficulties have been much discussed by many philosophers, who
have proposed many different approaches. But in view of the known
failure of classical physics to be able to describe the *macroscopic
properties* of systems whose behaviors can depend sensitively on the
behaviors of their atomic constituents, and the further fact that
orthodox contemporary physical theory brings conscious choices by human
agents into physical theory in an essential way, the question must be
asked whether these philosophical efforts accord with twentieth century
science, or are, instead, clever ways of trying to justifying the use of
approximately valid but fundamentally incorrect nineteenth century
physics in a domain where that approximation is inadequate.

Both of the above-mentioned difficulties are resolved in a rationally
coherent and practically useful way by quantum mechanics. On the one
hand, a key basic precept of the quantum approach, as it is both
practiced and taught, is that choices made by human beings play a key
and irreducible role in the dynamics. On the other hand, the great
disparity within classical physics between the experiential and physical
aspects of nature is resolved in the quantum approach by altering the
assumptions about the nature of the physical universe. The physical
world, as it appears in the theory, is transformed from a structure
based on *substance* or *matter* to one based on *events*, each of which
has both experiential aspects and physical aspects: Each such event
injects information, or "knowledge", into an information-bearing
mathematically described physical state. An important feature of this
radical revamping of the conceptual foundations is that it leaves
unchanged, at the practical level, most of classical physics. Apart from
making room for, *and a strict need for*, efficacious conscious choices,
the radical changes introduced at the foundational level by quantum
mechanics preserve at the pragmatic level almost all of classical
physics.

In the remainder of this introductory section I shall sketch out the
transition from the classical-physics conception of reality to von
Neumann's application of the principles of quantum physics to our
conscious brains. In succeeding sections I describe the most prominent
of the many efforts now being made by physicists to apply von Neumann's
theory to recent developments in neuroscience.

The quantum conception of the connection between the psychologically and
physically described components of scientific practice was achieved by
abandoning the classical picture of the physical world that had ruled
science since the time of Newton, Galileo, and Descartes. The building
blocks of science were shifted from descriptions of the behaviors of
tiny bits of mindless matter to accounts of *the actions that we take to
acquire knowledge* and of the *knowledge that we thereby acquire*.
Science was thereby transformed from its seventeenth century form, which
effectively excluded our conscious thoughts from any causal role in the
mechanical workings of Nature, to its twentieth century form, which
focuses on our active engagement with Nature, and on what we can learn
by taking appropriate actions.

Twentieth century developments have thus highlighted the fact that
*science is a human activity* that involves us not as passive witnesses
of a mechanically controlled universe, but as agents that can freely
choose to perform causally efficacious actions. The basic laws of
nature, as they are now understood, not only fail to determine how we
will act, but, moreover, inject our *choices about how to act* directly
into the dynamical equations.

This altered role of conscious agents is poetically expressed by Bohr's
famous dictum:

> "In the great drama of existence we ourselves are both actors and
> spectators." (Bohr, 1963, p. 15: 1958, p. 81)

It is more concretely expressed in statements such as:

> \"The freedom of experimentation, presupposed in classical physics, is
> of course retained and corresponds to the free choice of experimental
> arrangement for which the mathematical structure of the quantum
> mechanical formalism offers the appropriate latitude.\" (Bohr, 1958,
> p. 73}

The most important innovation of quantum theory, from a philosophical
perspective, is the fact that it is formulated in terms of an
*interaction* between the physically described world and conscious
agents who are, *within the causal structure defined by the known
physical laws*, *free to choose* which aspect of nature they will probe.
This crack, or gap, in the mechanistic world view leads to profound
changes in our conception of nature and the place of human beings within
it.

Another key innovation pertains to the *nature* of the *stuff* of the
physically/mathematically described universe. The switch is succinctly
summarized in Heisenberg's famous assertion:

> "The conception of the objective reality of the elementary particles
> has thus evaporated not into the cloud of some obscure new reality
> concept, but into the transparent clarity of a mathematics that
> represents no longer the behavior of the particle but rather our
> knowledge of this behavior." (Heisenberg, 1958a)

What the quantum mathematics describes is not the locations of tiny bits
of matter. What it described by the mathematics is a causal structure
imbedded in space-time that carries or contains information or
knowledge, but no material substance. This structure is, on certain
occasions, abruptly altered by *discrete events* that inject new
information into it. But this carrier structure is not purely passive.
It has an active quality. It acts as a bearer of "objective tendencies"
or "potentia" or "propensities" for new events to occur. (Heisenberg,
1958b, p. 53).

To appreciate this new conception of the connection between
psychologically described empirical part and the mathematically
described physical part of the new scientific description of physical
phenomena one needs to contrast it with what came before.

*The Classical-Physics Approach.*

Classical physics arose from the theoretical effort of Isaac Newton to
account for the findings of Johannes Kepler and Galileo Galilei. Kepler
discovered that the planets move in orbits that depend on the location
of other physical objects - such as the sun - but not on the manner or
the timings of our observations: minute-by-minute viewings have no more
influence on a planetary orbit than daily, monthly, or annual
observations. The nature and timings of our observational acts have no
effect at all on the orbital motions described by Kepler. Galileo
observed that certain falling terrestrial objects have similar
properties. Newton then discovered that he could explain
*simultaneously* the celestial findings of Kepler and the terrestrial
findings of Galileo by postulating, in effect, that all objects in our
solar system are composed of tiny planet-like particles whose motions
are controlled by *laws* that refer to the relative locations of the
various particles, and that make no reference to any conscious acts of
experiencing. These acts are taken to be simply passive witnessings of
macroscopic properties of large conglomerations (such as tables and
chairs and measuring devices) of the tiny individually-invisible
particles.

Newton's laws involve instantaneous action at a distance: each particle
has an instantaneous effect on the motion of every other particle, no
matter how distant. Newton considered this non-local feature of his
theory to be unsatisfactory, but proposed no alternative. Eventually,
Albert Einstein, building on ideas of James Clerk Maxwell, constructed a
*local* classical theory in which all dynamical effects are generated by
contact interactions between mathematically described properties
localized at space-time points, and in which no effect is transmitted
faster than the speed of light.

All classical-physics models of Nature are *deterministic*: the state of
any isolated system at any time is completely fixed by the state of that
system at any earlier time. The Einstein-Maxwell theory is deterministic
in this sense, and also "local", in the just-mentioned sense that all
interactions are via contact interactions between neighboring localized
mathematically describable properties, and no influence propagates
faster than the speed of light.

By the end of the nineteenth century certain difficulties with the
general principles of classical physical theory had been uncovered. One
such difficulty was with "black-body radiation." If one analyzes the
electromagnetic radiation emitted from a tiny hole in a big hollow
heated sphere then it is found that the manner in which the emitted
energy is distributed over the various frequencies depends on the
temperature of the sphere, but not upon the chemical or physical
character of the interior surface of the sphere: the spectral
distribution depends neither on whether the interior surface is smooth
or rough nor on whether it is metallic or ceramic. This universality is
predicted by classical theory, but the specific form of the predicted
distribution differs greatly from what is empirically observed.

In 1900 Max Planck discovered a universal law of black-body radiation
that matches the empirical facts. This new law is incompatible with the
basic principles of classical physical theory, and involves a new
constant of Nature, which was identified and measured by Planck, and is
called "Planck's Constant." By now a huge number of empirical effects
have been found that depend upon this constant, and that conflict with
the predictions of classical physical theory.

During the twentieth century a theory was devised that accounts for all
of the successful predictions of classical physical theory, and also for
all of the departures of the predictions of classical theory from the
empirical facts. This theory is called quantum theory. No confirmed
violation of its principles has ever been found.

*The Quantum Approach.*

The core idea of the quantum approach is the seminal discovery by Werner
Heisenberg that the classical model of a physical system can be
considered to be an *approximation* to a quantum version of that model.
This quantum version is constructed by replacing each numerical quantity
of the classical model by an *action*: by an entity that acts on other
such entities, and for which the order in which the actions are
performed matters. The effect of this replacement is to convert each
point-like particle of the classical conceptualization---such as an
electron---to a smeared-out cloudlike structure that evolves, almost
always, in accordance with a quantum mechanical law of motion called the
Schroedinger equation. This law, like its classical analog, is local and
deterministic: the evolution in time is controlled by contact
interactions between localized parts, and the physical state of any
isolated system at any time is completely determined from its physical
state at any earlier time by these contact interactions. The cloud-like
structure that represents an individual "particle", such as an electron,
or proton, tends, under the control of the Schroedinger equation, to
spread out over an ever-growing region of space, whereas according to
the ideas of classical physics an electron always stays localized in a
very tiny region.

The local deterministic quantum law of motion is, in certain ways,
incredibly accurate: it correctly fixes *to one part in a hundred
million* the values of some measurable properties that classical physics
cannot predict.

However, this local deterministic quantum law of motion does not
correlate directly to human experience. For example, if the state of the
universe were to have developed from the big bang solely under the
control of the local deterministic Schroedinger equation then the
location of the *center* of the moon would be represented in the theory
by a structure spread out over a large part of the sky, in direct
contradiction to normal human experience.

This smeared-out character of the position of (the center-point of) a
macroscopic object, is a consequence of the famous Heisenberg
Uncertainty Principle, combined with the fact that tiny uncertainties at
the microscopic level usually get magnified over the course of time,
*by* *the Schroedinger equation acting alone*, to large uncertainties in
macroscopic properties, such as location.

Thus a mathematical equation---the Schroedinger equation---that is a
direct mathematical generalization of the laws of motion of classical
physical theory, and that yields many predictions of incomparable
accuracy, strongly conflicts with many facts of everyday experience
(e.g., with the fact that the apparent location of the center of the
moon is well defined to within, say 10 degrees, as observed from a
location on the surface of the earth). Contradictions of this kind must
be eliminated by a satisfactory formulation of quantum theory.

In order to put the accurate predictions of the quantum mathematics into
the framework of a rationally coherent and practically useful physical
theory the whole concept of what physical science is was transformed
from its nineteenth form---as a theory of the properties of a mechanical
model of Nature in which we ourselves are mechanical parts---to a theory
of the connection between the physically and psychologically described
aspects of actual scientific *practice*. In actual practice we are
agents that probe nature in ways of our own choosing, in order to
acquire knowledge that we can use. I shall now describe in more detail
how this pragmatic conception of science works in quantum theory.

*"The Observer" and "The Observed System" in Copenhagen Quantum Theory.*

The original formulation of quantum theory is called the Copenhagen
Interpretation because it was created by the physicists that Niels Bohr
had gathered around him in Copenhagen. A central precept of this
approach is that, in any particular application of quantum theory,
Nature is to be considered divided into two parts, "the observer" and
"the observed system." The observer consists of the stream of
consciousness of a human agent, together with the brain and body of that
person, and also the measuring devices that he or she uses to probe the
observed system.

Each observer describes himself and his knowledge in a language that
allows him to communicate to colleagues two kinds of information: *How
he has acted* in order to prepare himself - his mind, his body, and his
devices - to receive recognizable and reportable data; and *What he
learns* from the data he thereby acquires. This description is in terms
of the conscious experiences of the agent himself. It is a description
of his intentional probing actions, and of the experiential feedbacks
that he subsequently receives.

In actual scientific practice the experimenters are free to choose which
experiments they perform: the empirical procedures are determined by the
protocols and aims of the experimenters. This element of freedom is
emphasized by Bohr in statements such as:

> "To my mind there is no other alternative than to admit in this field
> of experience, we are dealing with individual phenomena and that our
> possibilities of handling the measuring instruments allow us to make a
> choice between the different complementary types of phenomena that we
> want to study. (Bohr, 1958, p. 51)

This freedom to choose is achieved in the Copenhagen formulation of
quantum theory by placing the empirically/psychologically described
observer outside the observed system that is being probed, and then
subjecting only the observed system to the rigorously enforced
mathematical laws.

The observed system is, according to both classical theory and quantum
theory, describable in terms of mathematical properties assigned to
points in space-time. However, the detailed forms of the laws that
govern the evolution in time of this mathematical structure, and of the
rules that specify the connection of this mathematical structure to the
empirical facts, are very different in the two theories.

I am endeavoring here to avoid mathematical technicalities. But the
essential conceptual difference between the two approaches rests
squarely on a certain technical difference. This difference can be
illustrated by a simple two-dimensional picture.

*The Paradigmatic Example.*

Consider an experiment in which an experimenter puts a Geiger counter at
some location with the intention of finding out whether or not this
device will "fire" during some specified time interval. The experiment
is designed to give one of two possible answers: 'Yes', the counter will
fire during the specified interval, or 'No', the counter will not fire
during this specified interval. This is the paradigmatic quantum
measurement process.

This experiment has *two* alternative mutually exclusive possible
responses, 'Yes' or 'No.' *Consequently*, the key mathematical
connections can be pictured in a *two*-dimensional space, such as the
top of your desk.

Consider two distinct points on the top of your desk called *zero* and
*p*. The displacement that would move a point placed on *zero* to the
point *p* is called a *vector*. Let it be called *V*. Suppose *V* has
unit length in some units, say meters. Consider any two other
displacements *V1* and *V2* on the desk top that start from zero, have
unit length, and are perpendicular to each other. The displacement *V*
can be formed in a unique way by making a (positive or negative)
displacement along *V1* followed by a (positive or negative)
displacement along *V2*. Let the lengths of these two displacements be
called *X1* and *X2*, respectively. The theorem of Pythagoras says that
*X1* squared plus *X2* squared is one (unity).

Quantum theory is based on the idea that the various experiencable
outcomes have "images" in a vector space. The vector V1 mentioned above
is the image, or representation, in the vector space of the possible
outcome 'Yes,' whereas V2 represents 'No.' I will not try to describe
here how this mapping of possible experiencable outcomes into
corresponding vectors is achieved. But the basic presumption in quantum
theory is that such a mapping exists.

The vector *V* represents the state of the to-be-observed system, which
has been prepared at some earlier time, and has been evolving in
accordance with the Schroedinger equation. The vector *V1* represents
the state that this observed system would be known to be in if the
observed outcome of the measurement were 'Yes.' The vector *V2*
represents the state that the observed system would be known to be in if
the observed result of the measurement were 'No.' Of course, the
directions of the two perpendicular vectors *V1* and *V2* depend upon
the exact details of the experiment: on exactly where the experimenters
have placed the Geiger counter, and on other details controlled by the
experimenters.

The outcome of the probing measurement will be either *V1* (Yes) or *V2*
(No). The predicted probability for the outcome to be 'Yes' is *X1*
squared and the predicted probability for the outcome to be 'No' is *X2*
squared. These two probabilities sum to unity, by virtue of the theorem
of Pythagoras. The sudden jump of the state from *V* to either *V1* or
*V2* is called a "quantum jump." The *general* theory is expressed in
terms of a many-dimensional generalization of your desktop. This
generalization is called a Hilbert space, and every observable state of
a physical system is a represented by a "vector" in such a space.

The crucial, though trivial, logical point can now be stated: The two
alternative possible outcomes, 'Yes' or 'No' of the
chosen-by-the-experimenter experiment are associated with a pair of
perpendicular unit-length vectors called "basis vectors". The
*orientation* (i.e., directions) of the set of "basis" vectors, *V1* and
*V2,* enters into the dynamics as a *free variable* controlled by the
experimental conditions, which are specified in practice by choices made
by experimenters. The orientation of the set of basis vectors is thus,
from a mathematical standpoint, a variable that can be, and is,
specified *independently* of the state *V* of the system being probed.

This entry into the dynamics of choices made by the experimenters is not
at all surprising. If the experimenters are considered to stand outside,
and apart from, the system being observed, as specified by the
Copenhagen approach, then it is completely reasonable and natural that
the choices made by the experimenters (about how to probe the observed
system) should be treated as variables that are independent of the
variables that specify the physical state of the system they are
probing.

Bohr (1958: 92, p. 100) argued that quantum theory should not be applied
to living systems. He also argued that the classical concepts were
inadequate for that purpose. So the strict Copenhagen approach is simply
to renounce the applicability of *contemporary* physical theories, both
classical and quantum, to neurobiology.

*Von Neumann's Formulation.*

The great mathematician and logician John von Neumann (1955/1932)
rigorized and extended quantum theory to the point of being able to
corporate the devices, the body, and the brain of the observers into the
physically described part of the theory, leaving, in the psychologically
described part, only the stream of conscious experiences of the agents.
The part of the physically described system being directly acted upon by
a psychologically described "observer" is, according to von Neumann's
formulation, *the brain of that observer*. (von Neumann, 1955, p. 421).
The quantum jump of the state of the brain of an observer to the 'Yes'
basis state (vector) then becomes the representation, *in the state of
that brain*, of the conscious acquisition of the knowledge associated
with that answer 'Yes.' Thus the physical features of the brain state
actualized by the quantum jump to the state V1 associated with the
answer 'Yes' constitute the *neural correlate* of that person's
conscious experience of the feedback 'Yes.' This fixes the essential
quantum link between consciousness and neuroscience.

This is the key point! Quantum physics is built around "events" that
have both physical and phenomenal aspects. The events are physical
because they are represented in the physical/mathematical description by
a "quantum jump" to one or another of the basis state vectors defined by
the agent/observer's choice of what question to ask. If the resulting
event is such that the 'Yes' feedback experience occurs then this event
"collapses" the prior physical state to a new physical state compatible
with that phenomenal experience. Mind and matter thereby become
dynamically linked in a way that is causally tied to the agent's free
choice of how he or she will act. Thus a causal dynamical connection is
established between (1) a person's conscious choices of how to act, (2)
that person's consciously experienced increments in knowledge, and (3)
the physical actualizations of the neural correlates of the experienced
increments in knowledge.

This conceptualization of the structure of basic physical theory is
radically different from what it was in classical physics. Classical
physics was based on a guess that very worked well for two centuries,
namely the notion that the concepts that provided an "understanding" of
our observations of planets and falling apples would continue to work
all the way down to the elementary-particle level. That conjecture
worked well until science became able to explore what was happening at
the elementary-particle or atomic level. Then it was found that that
simple "planetary" idea could not be right. Hence scientists turned to a
more sophisticated approach that was based *less* on simplistic
ontological pre-suppositions and *more* on the empirical realities of
actual scientific practice.

This new conceptual structure is not some wild philosophical
speculation. It rationally yields---when combined with the statistical
rule associated with the theorem of Pythagoras described above---all the
pragmatic results of quantum theory, which include, as special cases,
all the valid predictions of classical physics!

Von Neumann shifted the boundary between the observer and the observed
system, in a series of steps, until the bodies and brains of all
observers, and everything else that classical physics would describe as
"physical", was included as part of the observed system, and showed that
this form of the theory is essentially equivalent, in practice, to the
Copenhagen interpretation. But it evades an unnatural feature imposed by
Bohr: it by-passes the ad hoc separation of the dynamically unified
physical world into two differently described parts. Von Neumann's final
placement of the boundary allows the psychological description to
be---as is natural---the description of a stream of conscious
experiences that are the experiential sides of a sequence of events
whose physical sides actualize the neural correlates of those
experiences.

It is important that von Neumann's systematic enlargement of the
physical system to include eventually the bodies and brains of the
observers *does not disrupt the basic mathematical structure of the
theory.* In particular, it does not alter *the critical need to specify
the orientation of the set of basis vectors* (e.g., V1 and V2) in order
to make the theory work. *The specification of the basis states
continues to be undetermined by* *anything in contemporary physical
theory*, *even when the physical description is extended to include the
entire physical world, including the bodies and brains of all human
observers.*

This leap by von Neumann from the realm of atomic physics to the realm
of neuroscience was way ahead of its time. Neuroscience was then in a
relatively primitive state compared to what it is today. It had a long
way to go before mainstream interest turned to the question of the
connection between brains and conscious experiences. But 70 years of
brain science has brought the empirical side up to the level where the
details of the mind-brain connections are being actively probed, and
intricate results are being obtained that can be compared to the
predictions of the psycho-physical theory prepared long ago by John von
Neumann.

It is evident that a scientific approach to brain dynamics must *in
principle* use quantum theory, in order to deal properly with brain
processes that depend heavily on chemical and ionic processes. For
example, the release of neurotransmitter from a nerve terminal is
controlled by the motions of calcium ions, and these ions are small
enough so that the deterministic laws of classical physics necessarily
fail. *Quantum theory must in principle be used to describe the ion
dynamics.* But once one goes over to a quantum-mechanical description of
the ionic components of the brain, one must follow through and treat
also the conglomeration of these cloudlike entities, and the other
similar components of the brain, by the quantum rules, in order to
recover the connection of that mathematical structure to our conscious
experiences!

According to this quantum description, the state of the brain is itself
an expanding cloud-like structure in a high-dimensional space. Just as
the various points in the cloud that describes a single particle
represent different classically conceived possibilities for that single
particle (where it is and how it is moving), so do the various points in
the cloud that describes the brain represent different classically
conceived possible states of that brain. This cloud-like structure can,
and generally will, encompass, with appreciable weights, many
conflicting classical possibilities.

The job of the brain is to accept clues from the environment and then to
construct a "Template for Action" (an "executive" pattern of
neurological activity) that, if it endures, will issue the sequence of
neural signals that will cause some specific (and hopefully appropriate)
action to unfold. In the cloudlike structure that represents a brain,
many alternative conflicting Templates for Action can arise. The
generation, within the quantum state of the brain, of important
components representing conflicting classical possibilities should occur
particularly when the low-level (essentially mechanical) processes
cannot come to agreement on the best course of action. In this
circumstance, the quantum mechanical rules allow choices to be made that
produce quantum jumps that, on the psychological side, inject new
experiences, associated with a newly chosen course of action, into the
stream of consciousness of the human agent, and that, on the physical
side, actualize brain states that contain the neural correlates of those
experiences. This is the basic dynamical process that underlies the
quantum approach to consciousness.

*Summary.*

The essential difference at the basic conceptual level between the
quantum and classical approaches to consciousness is that the classical
principles make no mention of consciousness. The causal structure is in
principle completely "bottom up." Everything is, in principle, fully
determined by what goes on at the microscopic atomic level, and any
dependence of microscopic properties upon macroscopic properties, or on
consciousness, is, in the end, a round-about consequence of laws
expressible exclusively in terms of properties of atomic particles and
of the physical fields that they produce. But in quantum theory the
local-deterministic (i.e., bottom-up) physical process is *in principle*
*causally incomplete*. It fixes, by itself, neither our actions nor our
experiences, nor even any statistical prediction about how we will act
or what we will experience. The bottom-up process *alone* is unable to
make statistical predictions, because the statistical predictions depend
upon the choice of a set of basis vectors, and the bottom-up
local-deterministic quantum process does not fix this choice.

This reorganization of the dynamical structure leads to an altered
perspective on the entire scientific enterprise. The psychologically
described empirical side of scientific practice is elevated from its
formerly subservient status - as something that should be *deduced*
from, or constructed from, the already-dynamically-complete physical
side - to the new status of co-equal dynamical partner. Science becomes
the endeavor to describe the *two-way* *interplay* between the
psychologically and physically described aspects of nature, rather than
an attempt to deduce the existence and properties of our streams of
conscious experiences from a presumed-to-be-dynamically-complete local
mechanical model.

Within the von Neumann framework our conscious choices fix the
orientations of the basis vectors. These choices can strongly influence
our actions. Thus these influences need not be illusions. The theory
provides, as we shall see in the section 4, a specific mechanism that
allows our conscious "free" choices to significantly influence our
physical actions.

*Pragmatic Neuroscience.*

Von Neumann, in his 1932 book followed the Copenhagen tack of focusing
on scientific practice rather than ontological issues. Indeed, it can be
argued that science is intrinsically pragmatic rather than ontological.
The true nature of things, other than our experiences themselves, can
never be provably ascertained by the methods of science. Thus Von
Neumann's formulation of quantum theory provides the foundations of a
*pragmatic* neuro-psycho-dynamics that is built on contemporary physical
theory, rather than an inadequate classical physics. All quantum
approaches to consciousness build upon this foundation laid by von
Neumann, but various physicists have proposed different ways of
developing that core structure. We turn now turn to the descriptions of
a number of these proposals.

**2. The Penrose-Hameroff Approach.**

Perhaps the most ambitious attempt to create a quantum theory of
consciousness is the one of Roger Penrose and Stuart Hameroff. Their
proposal has three parts: The Gödel Part, The Gravity Part, and the
Microtubule Part.

The Gödel Part, which is due to Penrose, is an effort to use the famous
Gödel Incompleteness Theorem to prove that human beings have
intellectual powers that they could not have if they functioned in
accordance with the principles of classical physical theory. Proving
this would reaffirm a conclusion of the von Neumann formulation of
quantum theory, namely that a conscious human being can behave in ways
that a classical mechanical model cannot. Penrose's argument, if valid,
would yield this same conclusion, but within a framework that relies not
on quantum concepts, which are generally unknown to cognitive
scientists, but rather on Gödel-type arguments, which are familiar to
some of them.

The general idea of Penrose's argument is to note that, due to the
mathematically deterministic character of the laws of classical physics,
the output at any specified finite time of any computer behaving in
accordance with the classical laws should in principle be deducible, to
arbitrarily good accuracy, from a finite-step procedure based on a
finite set of mutually consistent rules that encompass the laws of
arithmetic. But then a human being who can be adequately modeled as a
classical computer should be able to know, at any finite time, the truth
*only* of those statements that can be deduced from a finite-step
computation based on the finite set of rules that govern that computer.
Yet Gödel-theorem-type arguments allow real mathematicians to know,
given *any* finite set of consistent logical rules that encompass the
laws of arithmetic, the truth of mathematical statements that cannot be
deduced by any finite-step proof based on those rules. This seems to
imply that a real mathematician can know things that no classical
physics model of himself could ever know, namely the truth of statements
that his classical computer simulation could not establish in a finite
time.

Filling in the details of this argument is not an easy task. Penrose
spends the better part of five chapters in "The Emperor's New Mind,"
(Penrose, 1989) and some 200 pages in "Shadows of the Mind" (Penrose,
1994) explaining and defending this thesis. However, the Harvard
philosopher Hillary Putnam challenged Penrose's conclusion in a debate
appearing in the New York Times Review of Books, (Putnam, 1994) and
numerous logicians have since weighed in, all, to my knowledge,
challenging the validity of Penrose's argument. Thus the Gödel Part of
the Penrose-Hameroff approach cannot now be regarded as having been
successfully established.

The Gravity Part of the Penrose-Hameroff approach addresses a key
question pertaining to the quantum dynamics: exactly *when* do the
sudden "quantum jumps" occur? In von Neumann's theory these jumps should
presumably occur when the neural correlates of conscious thoughts become
sufficiently well formed. But von Neumann gives no precise rule for when
this happens.

The lack of specificity on this issue of precisely "*when"* is a serious
liability of the von Neumann theory, insofar as it is construed as a
description of the ontological mind-matter reality itself. That
difficulty is the basic reason why both the original Copenhagen
formulation and von Neumann's extension of it eschew traditional
ontological commitments. They hew rather to the pragmatic position that
the job of science is to establish useful practical connections between
empirical findings and theoretical concepts, rather than advancing shaky
speculations about the ultimate Nature of reality. The pragmatic
position is that theoretical ideas that optimally provide reliable
practical connections between human experiences constitute, themselves,
our best *scientific* understanding of "reality." Added ontological
superstructures are viewed as not true science, because additions that
go beyond optimal theoretical descriptions of connections between human
experiences cannot be tested empirically.

Penrose wants to provide an ontology that has "real quantum jumps."
Hence he must face the question: when do these jumps occur?. He seeks to
solve this problem by linking it to a problem that arises when one
attempts to combine quantum theory with Einstein's theory of gravity.

Einstein's theory of gravity, namely General Relativity, is based of the
idea that space-time is not a rigid flat structure, as had previously
been thought, but is rather a *deformable medium*, and that the way it
is deformed is connected to the way that matter is distributed within
it. This idea was developed within the framework of classical physical
theory, and most applications of it are made within a classical-physics
idealization. But serious problems arise when the quantum character of
"matter" is considered. For, according to orthodox quantum theory, a
particle, such as an electron or an ion, has no well defined location:
its location is specified by a smeared out "probability cloud." But if
the locations of the material particles are not well defined then,
according to General Relativity, neither is the form of the space-time
structure in which the particle structures are imbedded.

Penrose conjectures that Nature abhors uncertainty in the structure of
space-time, and that when too much ambiguity arises in the space-time
structure a quantum jump to some less ambiguous structure will occur.
This "principle" allows him to tie quantum jumps to the amount of
uncertainty in the structure of space-time.

There is no compelling reason why Nature should be any more perturbed by
an uncertainty in the structure of space-time than by an uncertainty in
the distribution of matter. However, by adopting the principle that
Nature finds intolerable an *excessive ambiguity in* the *structure of
space-time* Penrose is able to propose a specific rule about when the
quantum jumps occur.

Penrose's rule depends on the fact that Planck's constant gives a
connection between energy and time: this constant divided by any
quantity of energy gives a corresponding interval of time. Thus if an
energy associated with a possible quantum jump can be defined then a
time interval associated with that potential jump becomes specified.

To identify the pertinent energy consider a simple case in which, say, a
small object is represented quantum mechanically by a small cloud that
divides into two similar parts, one moving off to the right, the other
moving off to the left. Both parts of the cloud are simultaneously
present, and each part produces *a different distortion* of the
underlying spacetime structure, because matter is distributed
differently in the two cases. One can compute the amount of energy that
it would take to pull apart, against their gravitational attraction, two
copies of the object, if each copy is located at the position specified
by one of the two clouds. If one divides Planck's constant by this
"gravitational energy" then a time interval associated with this
distortion of space-time into these two disparate structures becomes
defined. Penrose proposes that this time interval is the duration of
time for which Nature will *endure* this bifurcation of its space-time
structure into the two incompatible parts, before jumping to one or the
other of these two forms.

This conjectured rule is based on two very general features of Nature:
Planck's universal constant of action and the Newton-Einstein universal
law of gravitation. This universality makes the rule attractive, but no
reason is given why Nature must comply with this rule.

Does this rule have any empirical support?

An affirmative answer can be provided by linking Penrose's rule to
Hameroff's belief that consciousness is closely linked to the
*microtubular sub-structure of the neurons.* (Hameroff and Penrose,
1996)

It was once thought that the interiors of neurons were basically
structureless fluids. That conclusion arose from direct microscopic
examinations. But it turns out that in those early studies the internal
substructure was wiped out by the fixing agent. It is now known that
neurons are filled with an intricate structure of *microtubules*.

Each microtubule is a cylindrical structure that can extend over many
millimeters. The surface of the cylinder is formed by a spiral chain of
tubulin molecules, with each circuit formed by thirteen of these
molecules. The tubulin molecule has molecular weight of about 110,000
and it exists in two slightly different configurational forms. Each
tubulin molecule has a single special electron that can be in one of two
relatively stable locations. The molecule will be in one or the other of
the two configurational states according to which of these two locations
this special electron is occupying.

Hameroff is an anesthesiologist, and he noted that there is close
correspondence between, on the one hand, the measured effects of various
anesthetics upon consciousness and, on the other hand, the capacity of
these anaesthetics to diminish the ability of the special electron to
move from one stable location to the other. This suggests a possible
close connection between consciousness and the configurational activity
of microtubules.

This putative linkage allows an empirical test of Penrose's rule to be
made.

Suppose, in keeping with the case considered by Penrose, you are in a
situation where one of two possible experiences will probably occur. For
example, you might be staring at a Necker Cube, or walking in a dark
woods when a shadowy form jumps out and you must choose "fight" or
"flight," or perhaps you are checking your ability to freely choose to
raise or not raise your arm. Thus one of two alternative possible
experiences is likely to occur. Various experiments suggest that it
takes about half a second for an experience to arise. Given this time
interval, Penrose's formula specifies a certain corresponding energy.
Then Hameroff can compute, on the basis of available information
concerning the two configurational states of the tubulin molecule, how
many tubulin-molecule configurational shifts are needed to give this
energy.

The answer is about 1% of the estimated number of tubulin molecules in
the human brain. This result seems reasonable. Its reasonableness is
deemed significant, because the computed fraction could have come out to
be perhaps billions of times smaller than, or billions of times greater
than, 100%. The fact that the computed value is "in the ballpark"
supports the idea that consciousness may indeed be connected *via
Gravity* to tubulin configurational activity.

Given this rather radical idea---it was previously thought that gravity
was not essential to consciousness (orbiting astronauts can think) and
that the microtubules were merely a construction scaffolding for the
building and maintenance of the physical structure of the neurons---many
other exotic possibilities arise. The two configurational forms of the
tubulin molecule mean that it can hold a "bit" of information, so maybe
the microtubular structure forms the substrate of a complex *computer*
located within each neuron, thus greatly expanding the computational
power of the brain. And maybe each such computer is in fact a "quantum
computer." And maybe these quantum computers are all linked together to
form one giant brain-wide quantum computer. And maybe these hollow
micro-tubes form wave guides for quantum waves.

These exotic possibilities are exciting and heady ideas. They go far
beyond what conservative physicists are ready to accept, and far beyond
what the 1% number derived from Penrose's rule actually supports. What
is supported is merely a connection between consciousness and
microtubular activity, *without the presence* of the further stringent
*coherence conditions* required for the functioning of a quantum
computer.

"Coherence" means preservation of the "phase" relationships that allow
waves that have traveled via different paths to come back together so
that, for example, crest meets crest and trough meets trough to build an
enhanced effect. Quantum computation requires an effective isolation of
the quantum informational waves from the surrounding environment,
because any interaction between these waves and the environment tends to
destroy coherence, and the required isolation is difficult to maintain
in a warm, wet, noisy brain.

The simplest system that exhibits a behavior that depends strongly on
quantum interference effects, and for which the maintenance of
*coherence* is essential, is the famous "double-slit experiment." When
photons of a single wave length are allowed to pass, one at a time,
through a pair of closely spaced narrow slits, and each photon is later
detected by some small detection device that is imbedded in a large
array of such devices, one finds that *if the photonic system is not
allowed to perceptibly influence any environmental degree* *of freedom*
on its way to the detection device then the pattern of detected events
depends on an *interference* between the parts of the beam passing
through the two different slits. This pattern is very different from
what it is if the photon is allowed to perceptibly disturb, the
surrounding environment. Disturbing the environment produces a
"decoherence" effect, i.e., a weakening or disappearance of the
interference effects.

If a system interacts with its environment, it is difficult to prevent a
"perceptible influence" of the system on the environment. If even *a
single* *one* of the thousands of particles in the environment is
displaced by a discernible amount then the coherence is lost, and the
quantum interference effect will disappear.

Because the medium in which the putative quantum information waves are
moving involves different conformational states of huge tubulin
molecules of molecular weight \~110,000, it would seemingly be
exceedingly hard to ensure that the passage of these waves will not
disturb even one particle of the environment by a discernible amount.

Max Tegmark wrote an influential paper in Physical Review E. (Tegmark,
2000). It mathematically buttressed the intuition of most physicists
that the macroscopic coherence required by Penrose-Hameroff\-\--namely
that the microtubular conformal states can form the substrate of a
quantum computer that extends over a large part of the brain\-\-- could
not be realized in a living human brain. Tegmark concluded that the
coherence required for macroscopic quantum computation would be lost in
a ten trillionth of a second, and hence should play no role in
consciousness. This paper was widely heralded. However, Hagan, Hameroff,
and Tuszynski (2002) wrote a rejoinder in a later issue of the same
journal. They argued that some of Tegmark's assumptions departed
significantly from those of the Penrose-Hameroff model. The associated
corrections lengthened the coherence time by 8 or 9 orders of magnitude,
thus bringing the situation into a regime where the non-equilibrium
conditions in a living brain might become important: energetic
biological processes might conceivably intervene in a way that would
make up the still-needed factor of ten thousand. However, the details of
how this might happen were not supplied. Hence the issue is, I believe,
still up in the air, with no detailed explanation available to show how
the needed macroscopic quantum coherence could be maintained in a living
human brain.

It must be stressed, however, that these exotic "quantum computer"
effects are not necessary for the emergence of strong quantum effects
within the general framework supplied by the combination of Penrose's
rule pertaining to gravity and Hameroff's claim concerning the
importance of microtubules. According to von Neumann's general
formulation, the state of the brain---or of the microtubular part of the
brain---is adequately represented by what physicists call the "reduced
density matrix" of that subsystem. This representation depends only on
the variables of that subsystem itself (i.e., the brain, or microtubular
array) but nevertheless takes adequate account of the interactions of
that system with the environment. It keeps track of the quantum
coherence or lack thereof. Penrose's rule can be stated directly in
terms of the "reduced density matrix," which displays, ever more clearly
as the interaction with the environment grows, the two alternative
states of the brain---or of the microtubular array---that Nature must
choose between. This reduced-density-matrix representation shows that
the powerful decoherence effect produced by strong interactions with the
environment actually *aids* the implementation of Penrose's rule, which
is designed to specify *when* the quantum jump occurs (and perhaps to
which states the jump occurs). The capacity of the brain to be or not to
be *a quantum computer* is a very different question, involving
enormously more stringent conditions. It thus is important, for logical
clarity, to separate these two issues of the requirements for *quantum
computation* and for *quantum jumps*, even though they happen to be
interlocked in the particular scenario described by Penrose and
Hameroff.

**3. The Bohm Approach.**

The Copenhagen and von Neumann formulations of quantum theory are
non-deterministic. Both specify that human choices enter into the
dynamics, but neither specifies the causal origins of these choices. The
question thus arises: what determines these choices?

One possibility is that these choices arise in some yet-to-be-specified
way from what we conceive to be the *idealike aspect of reality*. That
option was pursued by Penrose, with his suggestion that our thoughts are
linked to Plato's world of ideal forms. Another---seemingly
different---possibility is that a *physical description* exists that is
more detailed than the smeared out cloudlike structures of the orthodox
formulations, and that this *more detailed physical description*
determines all features left undetermined in the orthodox formulations.

This second approach was developed by David Bohm (1952, 1993). His
formulation of quantum theory postulates, in effect, the existence of
the old-fashioned world of classical physical theory. This
classical-type world is supposed to exist *in* *addition to the
cloudlike wave function of orthodox quantum theory* and is supposed to
evolve in a way completely determined by what precedes it in time. Bohm
specifies new laws of motion that are able to reinstate determinism in a
way compatible with the predictions of quantum theory, but at the
expense of a very explicit abandonment of locality: Bohm's theory
entails very strong, and very long-range, instantaneous
action-at-a-distance.

One serious failing of Bohm's approach is that it was originally
formulated in a non-relativistic context, and it has not yet -- after
half a century and great effort -- been extended to cover
deterministically the most important domain in physics, namely the realm
of quantum electrodynamics. This is the theory that covers the atoms
that make up our bodies and brains, along with the tables, chairs,
automobiles, and computers that populate our daily lives. This
deficiency means that Bohm's theory is, at present, primarily a
philosophically interesting curiosity, not a viable deterministic
physical theory.

Also, Bohm's theory, at least in its original form, is not really
germane to the issue of consciousness. For Bohm's theory *successfully
achieved its aim,* which was precisely to get rid of consciousness:
i.e., to eliminate consciousness from the basic dynamical equations,
just as classical physics had done.

Bohm recognized, later on, that some understanding of consciousness was
needed, but he was led instead, to the notion of an infinite tower of
mechanical levels, each controlling the one below, with consciousness
somehow tied to the mystery of the infinite limit. (Bohm, 1986, 1990)
This infinite-tower idea tends to diminish the great achievement of the
original theory, which was to reinstate physical determinism in a simple
way.

Perhaps the most important use of Bohm's model is to provide an
understanding of the consequences of assuming, as some philosophers do,
that we live in a world in which everything is deterministically fixed
by purely physical processes, and our conscious choices are
epiphenomenal.

Bohm's model is an example of such a theory, which moreover agrees with
the predictions of quantum theory, at least in the non-relativistic
regime. It is thus instructive to examine Bohm's model, and see how,
within that deterministic framework in which consciousness plays no
fundamental causal role, consciousness nevertheless enters*, at the
level of scientific practice*, in just the way specified by the orthodox
formulations.

As explained in the introductory section, actual scientific practice
involves setting up experimental conditions that promote consciously
conceived objectives. In von Neumann's theory these consciously chosen
actions influence the subsequent course of events in the observed
system, which, according to von Neumann's version of quantum theory, is
primarily the brain of the human participant. A key point is that these
choices, made by the experimenter about how he or she will act, are
treated in von Neumann's theory, and also by Copenhagen quantum theory,
as *input data*, to be fixed by the experimenter: no matter what these
choices actually are, or where they come from, or what they actually do,
these conscious choices are *treated* in orthodox quantum theory as
free, controllable, and knowable, input boundary conditions.

In Bohm's theory these choices are not *actually* free: freedom is an
illusion. The apparently free choice is, at a deeper dynamical level,
completely determined by *physical* conditions, just as it was in
classical physics. However, the putative existence of this deeper
dynamical underpinning does not upset scientific practice. It does not
displace, within science, the orthodox quantum dynamics. The analysis by
Heisenberg shows that, even within the context of a deterministic
Bohmian mechanics, the human observers can never determine, or *know*,
to which of the conceivable logically possible classical Bohmian worlds
their experiences belong. The Heisenberg Uncertainty Principle is a
limitation upon human knowledge that is not evaded by Bohm's
deterministic dynamics. The most that "experiencers" can ever *know*
about the Bohmian classical world of which they are a putative part is
represented by a quantum mechanical cloud-like wave function.

This limitation *in human knowledge* is acknowledged by Bohm. Indeed,
Bohm's theory leaves actual scientific practice the same as it is in the
Copenhagen approach. This *equivalence at the practical level* of Bohm's
model to the Copenhagen formulation means that the unavoidable gap *in
human knowledge* mandated by the uncertainty principle forces a return,
at the level of scientific practice, to Copenhagen quantum theory. The
theoretically specified, *but in principle unknowable and uncontrollable
information about the supposedly deterministic microscopic realities,*
are replaced in actual practice by *knowable and controllable
realities*, namely our human conscious choices about which actions we
will take, and their consciously experienced feedbacks. But this means
that the structure added by Bohm lies beyond the scope of science, in
the sense that it adds nothing testable. It is pure speculation.

An important feature of quantum theory, as it is understood by
physicists, is the never rebutted argument of the founders that any
added superstructure of the general kind proposed by Bohm can never add
anything testable, and hence lies outside science. Quantum physicists
tend to be skeptical of any claim that ascribes reality to properties
that are unknowable *in principle* and give nothing testable. They
identify science with actual scientific practice, not untestable
philosophical speculations. This attitude may be as beneficial in
neuroscience as it is in atomic physics.

**4. The von Neumann/Stapp Approach**

John von Neumann converted Copenhagen quantum theory, in a series of
steps, into a form in which the entire physical universe, including the
brain of each agent, is represented in one basic quantum state, which is
called the state of the universe. The state of any subsystem, such as a
brain, is formed by averaging (tracing) this basic state over all
variables *other* than those that describe the state of that subsystem.
The dynamics consists of *three* processes.

Process **1** is the choice on the part of the experimenter about how to
act. This choice is sometimes called "The Heisenberg Choice", because
Heisenberg strongly emphasized its crucial role in quantum dynamics. At
the pragmatic level it is a "free choice", because it is controlled *in
practice* by the conscious intentions of the experimenter/participant,
and neither the Copenhagen nor von Neumann formulations provide any
description of the *causal origins* of this choice, apart from the
thoughts, ideas, and feelings of the agent. Each intentional action
involves an effort to produce a conceived experiential feedback, which,
if it occurs, will be an experiential confirmation of the success of
that effort.

Process **2** is the quantum analog of the equations of motion of
classical physics. As in classical physics, these equations of motion
are local: all interactions are between immediate neighbors. They are
also deterministic. They are obtained from the classical equations by a
certain *quantization* procedure, and are reduced to the classical
equations by taking the *classical approximation* of setting to zero the
value of Planck's constant everywhere it appears. Evolution via the
quantum Process **2** normally has the effect of *expanding* the
microscopic uncertainties beyond what is demanded by the Heisenberg
Uncertainty Principle: the cloud of microscopic possibilities *spreads
out*. This growth in the microscopic regime, if unchecked by any other
process, spreads into the macroscopic domain and causes even the
*centers* of large objects to tend to become diffused over large
regions. The disparity between this Process-**2**-generated theoretical
indefiniteness of the locations of the centers of large objects and the
consciously experienced definiteness of the positions of visible objects
is resolved by Process **3**.

Process **3** is sometimes call the "Dirac Choice". Dirac called it a
"choice on the part of Nature." It can be regarded as Nature's answer to
the question posed by Process **1**. This posed question might be: "Will
the detecting device be found to be in the state that signifies "Yes, a
detection has occurred"? Or, "Will the Geiger counter be observed to
'fire' in accordance with the experiential conditions that define a
\`Yes' response?" Each Process **3** reply must be preceded by a Process
**1** question. This is because the Process **2** generates a
*continuous infinity* of possible questions that cannot all be answered
consistently within the mathematical framework provided by quantum
theory. Process **1** specifies a set of distinct allowed possible
answers such that the "Pythagoras Rule" for probabilities yields the
conclusion that the probabilities for the allowed possible answers sum
to unity.

Process **1** brings the conscious choices made by the
observer/participant directly into the dynamics. On the other hand,
there is a tendency for the effect of the Process-**1** choices (of the
questions) on the state of observed system to be washed out, in the long
run, by the averaging over the two possible answers, \`Yes' and 'No.'
However, it has been stressed by Stapp (1999) that if willful effort can
control the *rate* at which a sequence of similar Process 1 events occur
then the course of brain events could be strongly affected by mental
effort. The timing of the Process-**1** events is, within the orthodox
Copenhagen/von Neumann quantum theoretical framework, governed be the
choice made by the experimenter/agent, and this choice is not specified
by any known law of physics. But a rapid sequence of pairs of questions
and answers (Process-**1**/Process-**3** events) can, by virtue of the
quantum laws themselves, hold a particular pattern of neurological
activity in place, against the physical forces that would, both in the
absence of such pairs, and also in classical physics, tend quickly to
disrupt it. If this pattern of neurological activity were to be a
"Template for Action" (i.e., an "executive" pattern of neurological
activity that tends to produce a specific action) then the prolongation
of the activation of this "executive pattern" of brain activity can tend
to cause the intended bodily action to occur, in accordance with William
James's "ideo-motor" theory of action (James, 1890, p. 522). (According
to that theory, it is the holding in place of the idea of an action that
tends to make that action happen.)

This fact that a sufficiently rapid sequence of consciously selected
probing events can hold the associated pattern of physical activity in
place longer than what would be specified either by the classical laws
of motion or its quantum analog, Process **2**, is *an automatic
consequence of the quantum laws of motion*. It has been extensively
studied by quantum physicists, both empirically (Itano, Heinzen,
Bollinger, and Wineland, 1990) and theoretically (Misra and Sudarshan,
1977), under the title "Quantum Zeno Effect."

This quantum process can provide a physics-based account of the causal
efficacy of conscious willful effort. This account corresponds closely
to the ideas of William James, as is made evident by the following
quotations:

> \`\`Thus we find that we reach the heart of our inquiry into volition
> when we ask by what process is it that the thought of any given action
> comes to prevail stably in the mind.\'\' (James, 1890, p. 564)

and later

> \`\`The essential achievement of the will, in short, when it is most
> \`voluntary,\' is to attend to a difficult object and hold it fast
> before the mind. \... Effort of attention is thus the essential
> phenomenon of will.\'\'

Still later, James says:

> ."Everywhere, then, the function of effort is the same: to keep
> affirming and adopting the thought which, if left to itself, would
> slip away.\'\'

The conclusion here is that the apparent capacity of our conscious
efforts/choices to influence our physical actions, which seems so
puzzling and necessarily illusory within classical physics, has a
straightforward explanation within quantum theory. This causal
connection follows directly from the orthodox quantum laws of motion.
Moreover, the details of how the process works is in close accord with
William James's account of how willful effort brings about intended
actions. Unlike the situation in classical physics, these willful
choices themselves are not controlled by the known laws of physics.
There is, therefore, no warrant in contemporary physical theory for the
assumption that our human choices are strict consequences of local
mechanical processes akin to, or analogous to, those appearing in the
classical physics approximation. The classical approximation completely
wipes out the uncertainties within which the free choices are allowed to
act. This approximation contracts the spreading cloud-like structures of
quantum theory into narrow pencil-like beams, thus eliminating the
freedom provided by quantum theory that Bohr strongly emphasized. In
contrast to the Process **3** choices on the part of nature, which are
subject to statistical laws, and hence are forced to be "random", the
Process **1** choices on the part of agents are not subject to any known
law, statistical or otherwise, and hence need not be ruled by pure
chance. This is important, because it is often claimed by the
ill-informed that all of the indeterminateness introduced by quantum
theory is controlled by statistical laws, and is hence "random". But the
crucial Process 1 choices on the part of the agents are not subject to
any known *statistical or deterministic* conditions.

In quantum theory the connection between mental effort and physical
action can be explained as a *causal consequence* *of* *the laws of
quantum physics*, combined with an assumption that an agent's conscious
effort to produce some experientially characterized effect increases the
rapidity of a set of Process-**1** probing actions that focus attention
on the intended experience. The experiential side of each such
Process-**1** action/event is specified by an intended (projected)
experiential state. The physical side collapses the prior physical state
of the brain to a sum of two parts. The first part is the part of the
prior state in which the neural correlate (Template for Action) of the
conscious intention is definitely present. The second part is the part
of the prior state in which the neural correlate of the conscious
intention is definitely not present. In quantum theory there are
generally parts of the prior state that are not compatible with either
of those possibilities. Those parts are eliminated by Process **1**,
which is thus associated with *asking* a question. Process **3** gives
nature's immediate answer: it collapses the state to the 'Yes' part or
to the 'No' part. These pairs of abrupt events can be regarded as the
"posing by agents" and the "answering by nature" of specific
experientially formulated questions with 'Yes' or 'No' answers. *These
events with their associated experiential and physical sides are the
basic building blocks of quantum mechanics.* Between such event-pairs
the state evolves via the local mechanical process **2** that is
analogous to the local deterministic law of motion in classical physics.

This tripartite quantum dynamics involving Choice, Causation, and Chance
(Processes **1**, **2**, & **3**, respectively) and the implementation
of Will (Volition) via the conscious control of the rapidity of Process
**1** events, provides the mathematical and logical foundation of a
*pragmatic* quantum approach to neuro-psychology. How well does this
pragmatic quantum approach work in actual practice?

*Pashler's Analysis.*

A great deal of experimental work in the field of The Psychology of
Attention is summarized in Harold Pashler's recent book of that title
\[Pashler, 1998\].

Pashler organizes his discussion by separating perceptual processing
from post-perceptual processing. The former covers processing that,
first of all, identifies such basic properties of stimuli as location,
color, loudness, and pitch, and, secondly, identifies stimuli in terms
of categories of meaning. The post-perceptual process covers the tasks
of producing motor and cognitive actions beyond mere categorical
identification. Pashler emphasizes \[p. 33\] that \`\`the empirical
findings of attention studies specifically argue for a distinction
between perceptual limitations and more central limitations involved in
thought and the planning of action.\'\' The existence of these two
different processes, with different characteristics, is a principal
theme of Pashler\'s book. \[pp. 33, 263, 293, 317, 404.\] He argues that
the former processes are carried out in parallel, but that the latter
processes, which seem to require effortful choosing, operate in series,
and have a capacity that, although limited, can often be enlarged by
willful effort.

Pashler's conclusion is based on the analysis of a huge array of recent
experiments. But the central finding is succinctly illustrated in a
finding dating from the nineteenth century, namely that mental exertion
reduces the amount of physical force that a person can apply. He notes
that \`\`This puzzling phenomena remains unexplained.\'\' \[p. 387\].
However, if we take the sequence of Process I events associated with an
agent to have a limited "capacity" in terms of events per second, then
this effect is a natural consequence of quantum theory. Creating a
physical force by muscle contraction requires a *conscious effort* that
prolongs the existence of the neural template for action, in opposition
to the Process-**2**-generated tendency of the brain to evolve toward a
more relaxed state. This prolongation is produced by the Quantum Zeno
Effect, and its effect is roughly proportional to the number of bits per
second of central processing capacity that is devoted to the task. So if
part of this processing capacity is directed to another task, then the
applied force will diminish.

This example is just one simple case, but it illustrates the general
principle. The identification of Pashler's limited central serial
"capacity" with the rate of occurrence of Process **1** events, assumed
to be increasable by willful effort, up to a limit, appears to explain
the general features of all of the many diverse empirical results cited
by Pashler in support of his thesis. (Schwartz, Stapp, & Beauregard,
2003; Stapp, 2001)

The apparent success of this quantum psychophysical theory in accounting
for Pashler's data does not mean that classical physics could not be
supplemented in some ad hoc way that would enable it to match that
performance. However, the von Neumann theory allows the data to be
explained directly in terms of *the already existing explicitly
described tripartite process that constitutes the core of contemporary
basic physical theory*, whereas an explanation based on classical
physics is predicated on the untenable idea that the classical concepts
of causation can be extrapolated from the motions of planets and falling
apples to the motions of ions inside nerve terminals. It rests on a
theory that is not only demonstrably false, but that claims to be
dynamically and logically complete without entailing the existence of a
part of reality that we know does exist, namely human consciousness. In
contrast, von Neumann's equations specify definite dynamical connections
between consciousness and brain activity, and they do so in a
theoretical framework that automatically entails all of the valid
predictions of classical physics. So what is the rationale, in
neuro-psychology, for rejecting the fundamental equations and ideas of
contemporary physics, which can mathematically account for the "directly
observed" causal efficacy of consciousness, and also explain all of the
valid classical features of phenomena, in favor of an extrapolation of
"planetary" concepts into a microscopic regime where they are known to
fail.

*The Libet Experiment.*

Perhaps the best way to understand the essence of the quantum approach
to consciousness is to see how it applies to the famous Libet
experiments pertaining to willful action. (Libet, 2003)

The empirical fact established by the Libet data is that when an action
is 'willed'-- such as 'willing' a finger to rise-- a readiness potential
(RP) appears *before* the conscious experience of 'willing' appears. The
most straightforward conclusion is that the causal efficacy of "free
will" is an illusion. The motion of the finger seems clearly to be
caused by neural activity that began well before the conscious act of
"willing" occurs. Thus consciousness is seemingly a *consequence* of
neural activity, not a *cause* of it.

The quantum mechanical analysis of this experiment leads to a more
subtle conclusion.

In the Libet experiment the original commitment by the subject to, say,
"raise my finger within the next minute" will condition his brain to
tend to produce *a sequence* of potential RP's distributed over the next
minute. That is, the cloud of quantum possibilities will begin to
generate a sequence of possible RP's, each one beginning at a different
time. Each such RP will be associated with the 'Yes' answer to the
question "Shall I choose (make an effort) to raise my finger now?" If
the answer is 'No' then the 'template for the action of making an effort
to raise the finger at that moment' will not be actualized, and the
brain state associated with the answer 'No' will then evolve until the
possibility of actualizing the template and RP corresponding to a later
moment of choice arrives. When the brain activity associated with any
*one* of these RP's reaches a certain triggering condition the Process
**1** action associated with that particular RP will occur. Because the
original commitment is spread over a minute the probability, for any
individual RP in this sequence, for Nature's answer to be \`Yes' will be
small. Hence most of the possible RP's up to the one corresponding to
some particular moment will *not be actualized*: they will be eliminated
by the \`No' answer on the part of Nature. But for one of these Process
**1** events the associated Process **3** will deliver the answer "Yes,"
and the associated experience e will occur. Up to this point the
conscious will has entered only via the original commitment to raise the
finger sometime within the next minute. But in order to be efficacious
the later experience e must contain an element of effort, which will
cause the Process **1** associated with this experience (or a very
similar one) to occur quickly again, and then again and again, thereby
activating the Quantum Zeno Effect. This will cause the finger-raising
template for action to be held in place, and the effect of this will be
the issuing of the neural messages to the muscles that will cause the
finger to rise. Without this willful effort, which occurs in conjunction
with the answer 'Yes', the sustained activation of the template for
action will not occur and the finger will not rise. The willful effort
causes the rapid repetition of the Process 1 action to occur. This holds
the template in place, which causes the finger to rise. Thus the rising
of the finger is caused, in the quantum formulation, by the willful
effort, in concordance with the idea expressed by James (1892, 227)

> "I have spoken as if our attention were wholly determined by neural
> conditions. I believe that the array of things we can attend to is so
> determined. No object can catch our attention except by the neural
> machinery. But the amount of the attention which an object receives
> after it has caught our attention is another question. It often takes
> effort to keep mind upon it. We feel that we can make more or less of
> the effort as we choose. If this feeling be not deceptive, if our
> effort be a spiritual force, and an indeterminate one, then of course
> it contributes coequally with the cerebral conditions to the result.
> Though it introduces no new idea, it will deepen and prolong the stay
> in consciousness of innumerable ideas which else would fade
> more quickly away."

*Applications in Neuropsychology*

This theory has been applied to Neuropsychology. (Oschner, Bunge, Gross,
& Gabriel, 2002; Schwartz, Stapp, & Beauregard, 2003). In these studies
human subjects are first instructed how to alter their mental reactions
to emotionally-charged visual stimuli by adopting certain mental
strategies. For example, the subjects are trained how to reduce their
emotional reaction to a violent or sexual visual scene by cognitively
re-evaluating the content; for example, by interpreting or
contextualizing it in a different way. Their reactions to such stimuli
are then studied using fMRI under differing choices of mental set. The
brain scans reveal profoundly different patterns of response to the
stimuli according to whether the subject does or does not apply the
cognitive re-evaluation. Without cognitive re-evaluation the brain
reaction is focused in the limbic system, whereas when cognitive
re-evaluation is employed the focus shifts to pre-frontal regions. This
demonstrates the powerful effect of cognitive choices upon brain
functioning.

This effect is not surprising. Within the pragmatic framework this
effect appears as a causal connection between a psychologically
described input variable, namely a knowable and controllable free
conscious choice, and an ensuing brain behavior. Quantum theory contains
a mechanism that can explain this empirically observed apparent causal
effect of the conscious choice upon the ensuing brain activity, but no
explanation of any causal effect of brain process upon our conscious
choices. The contending classical approach asserts that the causal
connections are wholly in the opposite direction. It claims that both
the conscious choice and the subsequent brain behavior are both
consequences of prior physical processes.

Superficially, it might seem that there is no way to decide between
these contending theories, and hence that a scientist is free here to
choose between classical physics and quantum physics. It might be argued
that the dispute is all words, with no empirical or theoretical content.
However, the claim that the sufficient *cause* of the subject's
subsequent brain state does not include the controllable variable that
*empirically* controls it is prima facie unreasonable. It would become
reasonable only if supported by strong theoretical arguments or
empirical evidence. But there is no strong theoretical support. The only
theoretical support for this prima facie implausible claim comes from a
physical theory, classical physics, whose domain of applicability fails
in principle to cover the phenomena in question. The more accurate
physical theory that *should* cover these phenomena provides no support
at all for an epiphenomenal explanation of this data

This argument does not *prove* that a classical-type causal explanation
that leaves consciousness out is rationally untenable. However, if one
were to search for evidence to support the classical idea then most
scientists would probably agree that one must, at this point in time,
expect the data to be at least *compatible* with the predictions of
quantum theory. But then the example provided by Bohm's model becomes
instructive. That model is deterministic at the purely physical level,
without reference to consciousness. To be sure, it involves, in a direct
way, instantaneous long-range action at a distance, and it has not been
made compatible with the special theory of relativity. But the model
does give an idea of how consciousness *might* in principle be rendered
impotent in a model compatible with the *predictions* of quantum theory.
However, as discussed in the section on Bohm's model, the Heisenberg
uncertainty principle excludes the possibility of knowing anything
about, or testing for the presence of, the proposed causal substructure.
This circumstance argues for the adoption in neuroscience of the
attitude adopted in atomic physics: avoid the introduction of
speculative concepts that are unknowable and untestable in principle,
and, instead, treat conscious choices in the way that they actually
enter scientific practice, namely as empirically knowable and
controllable input parameters.

The basic elements of von Neumann's theory are the experiences of
conscious agents, and the neural correlates of those experiences, the
NCC's. The fundamental building blocks of quantum theory are
"information/action events". On the psychological level, each Process
**1** event focuses attention and effort on an intended
experiential/informational feedback. On the physical level this event
reduces (collapses) the state of the brain to a sum of two terms, one of
which is the neural correlate of the intended experience, and the other
of which is the neural correlate of the negation of that possibility.
Contemporary physical theory gives no statistical or deterministic
conditions on the choice of the intended action. But Nature's feedback
is required to conform to the "Pythagoras" statistical rule described
above.

How is the necessary connection between the experiential and physical
regimes established? The answer is by trial and error empirical testing
of the correspondence between "the feeling of the conscious effort" and
"the feeling of the experiential feedback". Every healthy alert infant
is incessantly engaged in mapping out the correspondences between
efforts and feedbacks, and he/she builds up over the course of time a
repertoire of correspondences between the feel of the effort and the
feel of the feedback. This is possible because different effortful
choices have, according to the quantum equations, different physical
consequences, which produce different experiential consequences. This
whole process of learning depends crucially upon the causal efficacy of
chosen willful efforts: if efforts have no actual consequences then how
can learning occur, and the fruits of learning be obtained by
appropriate effort.

The focus here has been on the theoretical foundations of pragmatic
neuroscience. However, von Neumann's formulation makes the theory more
amenable to ontological interpretation.

The essential difference between quantum theory and classical physics,
both ontologically construed, is that the classical state of the
universe represents a purported *material* realty, whereas the von
Neumann quantum state of the universe represents a purported
*informational* reality. This latter reality has certain matter-like
features. It can be expressed in terms of micro-local entities (local
quantum fields) that evolves by direct interactions with their
neighbors, *except* when certain abrupt "reductions" or "collapses"
occur. These sudden changes are sometimes called "quantum jumps." In
orthodox pragmatic quantum theory what the state represents is the
collective knowledge of all agents. Hence it abruptly changes whenever
the knowledge of any agent changes. This behavior is concordant with the
term "our knowledge" used by the founders of quantum theory. Thus the
quantum state has a *form* that manifests *certain* of the mechanical
properties of matter, but a *content* that is basically idealike: it
represents an objective kind of knowledge that changes when someone
acquires knowledge.

This radical revamping of physics was not something lightly entered into
by the founders of quantum theory, or docilely accepted by their
colleagues. A blithe disregard, in the study of the mind-brain
connection, of this profound and profoundly relevant revision by
scientists of the idea of the interplay between the experiential and
physical aspects of nature is not easy to justify. .

If one shifts over to an explicitly ontological interpretation, the
question arises "What systems besides human beings are *agents?* There
is currently a lack of replicable empirical data that bears on this
question, and I shall therefore not enter into philosophical
speculation.

It needs to be emphasized that everything said about the von Neumann
theory is completely compatible with there being very strong
interactions between the brain and its environment. The state S(t) of
the brain is what is known as the statistical operator (reduced density
matrix) corresponding to the brain. It is formed by averaging (tracing)
over all non-brain degrees of freedom, and it automatically incorporates
all of the decoherence effects arising from interactions with the
environment. The key point is that strong environmental decoherence does
not block the Quantum Zeno Effect.

There is an approach to quantum theory that tries to ignore von
Neumann's Process **1** (and Process **3** as well). This approach is
called the "many-minds" or "many-worlds" approach. No demonstration has
been given that such a radical break with orthodox quantum theory is
mathematically possible. Hence I do not include it among the possible
quantum approaches to consciousness described here.

Von Neumann's theory provides a general physics-based psycho-physical
framework for studying the neuroscience of consciousness. We now turn to
some efforts to tie this structure to the detailed structure of the
brain

**5. The Eccles-Beck Approach.**

Sir John Eccles suggested in 1990, in the Proceedings of the Royal
Society (Eccles, 1990), that quantum theory plays a key role in the
workings of the conscious brain. Based in part on his discussions with
Henry Margenau (See Margenau, 1984), Eccles noted that the statistical
element in quantum theory allows an escape from the rigid determinism of
classical physics that has plagued philosophy since the time of Isaac
Newton. In his later book "How the self controls its Brain" Eccles
(1994) notes that, "There is of course an entrenched materialist
orthodoxy, both philosophic and scientific, that rises to defend its
dogmas with a self-righteousness scarcely equaled in the ancient days of
religious dogmatism." He says at the outset that, "Following Popper
(1968) I can say:

I wish to confess, however, at the very beginning, that I am a realist:
I suggest somewhat like a naïve realist that there is a physical world
and a world of states of consciousness, and that these two interact."

Eccles gives "two most weighty reasons" for rejecting the
classical-physics-based concept of materialism. (Eccles 1994, p, 9)
First, classical physics does not entail the existence or emergence of
the defining characteristic of consciousness, namely "feelings," and
hence entails no theory of consciousness. Second, because the Nature of
the mapping between brain states and states of consciousness never
enters into the behavior of an organism, there is no evolutionary reason
for consciousness to be closely connected to behavior, which it clearly
is.

Eccles' approach to the mind-brain problem has three main points. The
first is that consciousness is composed of elemental mental units called
psychons, and that each psychon is associated with the activation of a
corresponding macroscopic physical structure in the cerebral cortex that
Eccles calls a *dendron*. It is anatomically defined, and is connected
to the rest of the brain via a large number of synapses.

The second point is the claim that quantum theory enters brain dynamics
in connection with exocytosis, which is the release of the contents of a
"vesicle" -- filled with neurotransmitter -- from a nerve terminal into
a synaptic cleft.

The third point is a model developed by the physicist Friedrich Beck
that describes the quantum mechanical details of the process of
exocytosis.

The first claim, that psychological processes have elemental units
associated with dendrons, places Eccles' theory somewhat apart from
those who have suggested that *the electromagnetic field* in the brain
might serve as the carrier of the physical correlate of consciousness.
(McFadden, 2002; Pockett, 2000, 2002: Stapp, 1985, 1987; Taylor, 2002)
Evidence for the electromagnetic hypothesis has been presented
particularly by McFadden. However, the very close causal connection
between the activation of a dendron and the activation of an
electromagnetic field in the neighborhood of that dendron makes it
difficult to distinguish between these two proposals empirically.

More germane to our topic is the second component of Eccles' proposal,
namely that quantum effects are important in brain dynamics in
connection with cerebral exocytosis. This conclusion is plausible, and
indeed inescapable. Exocytosis is instigated by an action potential
pulse that triggers an influx of calcium ions through ion channels into
a nerve terminal. These calcium ions migrate from the ion-channel exits
to sites on or near the vesicles, where they trigger the release of the
contents of the vesicle into the synaptic cleft. The diameter of the ion
channel through which the calcium ion enters the nerve terminal is very
small, less than a nanometer, and this creates, in accordance with the
Heisenberg uncertainty principle, a correspondingly large uncertainly in
the direction of the motion of the ion. That means that the quantum wave
packet that describes the location of the ion spreads out, during its
travel from ion channel to trigger site, to a size much larger than the
trigger site (Stapp 1993; Stapp,2003). That means that the issue of
whether or not the calcium ion (in combination with other calcium ions)
produces an exocytosis is a quantum question basically similar to the
question of whether or not a quantum particle passes through one or the
other slit of a double-slit experiment. According to quantum theory the
answer is 'both.' Until the brain process reaches the level of
organization corresponding to the occurrence of a Process I action one
must in principle retain *all* of the possibilities generated by the
Schroedinger equation, Process **2**. In particular, one must retain
both the possibility that the ion activates the trigger, and exocytosis
occurs, and also the possibility that the ion misses the trigger site,
and exocytosis does not occur.

For cortical nerve terminals the observed fraction of action potential
pulses that result in exocytosis is considerably less than 100%. This
can be modeled classically. (Fogelson & Zucker, 1985) But the large
Heisenberg uncertainty in the locations of the triggering calcium ions,
entails that the classical uncertainties will carry over to similar
quantum uncertainties, and the two possibilities at each synapse,
'exocytosis' and 'no exocytosis', will, prior to the occurrence of the
Process **3** action, *both be present* in the quantum state S(t). If N
such synaptic events occur in the brain during some interval of time in
which no Process **3** events occur, then the state S(t) of the brain
will evolve during that interval into a form that contains (at least)
2^N^ contributions, one for each of the alternative possible
combinations of the 'exocytosis' and 'no exocytosis' options at each of
the N synapse events.

There is a lot of parallel processing and redundancy in brain dynamics
and many of these possible contributions may correspond to exactly the
same possible experience 'e'. But in real life situations where there
could be several different reasonable actions, one cannot expect that
every one of the 2^N^ alternative possible brain states will be a neural
correlate of *exactly* the same possible 'e'. If the agent is conscious
then the von Neumann Processes **1** and **3** must enter to determine
which of the various alternative possible experiences 'e' actually
occurs.

The analysis just given assumes, in accordance with the model of
Fogelson and Zucker, that the condition that triggers exocytosis is the
presence of a specified number of calcium ions on a trigger site. Beck
(2003) considers another possibility. He says that the "low exocytosis
probability per excitatory impulse ...means that there is an activation
barrier against opening an ion channel in the PVG (presynaptic vesicular
grid). He proposes that "An incoming nerve pulse excites some electronic
configuration to a metastable level, separated energetically by a
potential barrier V(q) from the state that leads to the unidirectional
process of exocytosis." In this scenario the state in which the
exocytosis does occur can be considered to be connected by a *quantum
tunneling process* to the state where it does not occur*.*

*Beck's tunneling mechanism would achieve the same result as the*
mechanism, described above, which is based simply on the spreading of
the wave packets of the calcium ions due to Heisenberg's uncertainty
principle. Both mechanisms lead to the result that the brain state S(t)
will contain 2^N^ states, defined by the independent 'exocytosis or no
exocytosis' option at each of the N synapses. Hence the Eccles-Beck
model does not lead to any essential difference, as regards this key
point, from the model that emphasizes the spreading of the calcium ions
inside the nerve terminal. (Of course, it should not be thought that
these explicitly considered effects are the *only* places where quantum
effects enter into brain dynamics. These explicitly treated processes
are just special case where enough empirical evidence is available to
make a calculation, and where the alternative possibilities should feed
into the generation of non-identical brain states.)

The Eccles-Beck proposal does, however, differ significantly from the
von Neumann/Stapp proposal in regard to their third point. The von
Neumann/Stapp theory attributes the efficacy of will to the assumed
power of mental effort to increase the rate of Process **1** actions,
whereas the Eccles-Beck proposal attributes the efficacy of will to the
assumed power of mental effort to modify *the probabilities associated
with the Process **3** action*, the collapse of the quantum state.

The von Neumann/Stapp proposal stays rigorously within the framework of
relativistic quantum field theory, and hence produces no causal
anomalies, such as the possibility of sending messages backward in time.
The Eccles-Beck proposal, by violating the basic quantum probability
rules, would in principle allow such anomalies to occur.

It is often emphasized, *correctly*, in connection with quantum
approaches to brain dynamics, that "the environment" will be affected
differently by interactions with the brain states in which an exocytosis
has or has not occurred, and that this difference will destroy, almost
immediately, all (practically achievable) interference effects between
these macroscopically distinct states.

This *environmental decoherence effect* is automatically included in the
formulas used here, which refer explicitly to the brain state S(t),
which is the brain-state statistical operator obtained by averaging
(tracing) over all non-brain variables.

It is then sometimes concluded, *incorrectly*, that one can immediately
replace the brain state S(t) by just *one* of these 2^N^ components.
That conclusion might follow if one were to ignore Process **1**, which
is part of the brain process that defines which of our alternative
possible thoughts occurs next. Because Process **1** is part of the
process that determines which thought occurs next, it should depend upon
the state S(t) of the brain *before* the thought occurs, not on the part
of that state that will eventually be actualized. Hence all of the 2^N^
components of S(t) should be retained prior to the Process **3**
collapse,' whether they interfere or not:

The model of the brain used above, with its 2^N^ well defined distinct
components is, of course, highly idealized. A more realistic model would
exhibit the general smearing out of all properties that follows from the
quantum smearing out of the positions and velocities of all the
particles. Thus the state S(t) prior to the collapse cannot be expected
ever to be rigorously divided, solely by Process **2** action, including
interaction with the environment, into strictly orthogonal
non-interfering components corresponding to distinct experiences. It is
Process **1** that makes this crucial separation, not Process **2**. The
recognition of the need to bring in a *separate process* *to define the
question* is the critical element of the Copenhagen approach, and it was
formalized by von Neumann as Process **1**. Any attempt to leave out
Process **1** faces daunting challenges.

**6. The Jibu-Yasue Approach.**

The preceding sections are conservative and incomplete. They are
conservative because they: (1), build on the orthodox philosophy of
quantum theory, which recognizes that science, like every human
endeavor, arises from the fact that human beings choose their actions,
and experience the feedbacks; and (2), exploit the quantum laws that
relate these choices to those feedback.

The preceeding sections are incomplete because they say very little
about the actual brain mechanisms.

In regard to this second point there is a related question of how
memories are stored. Karl Pribram has suggested (Pribram, 1966, 1991)
that consciousness operates on principles similar to that of a hologram,
in which tiny variations of a myriad of physical variables, dispersed
over a large region, combine to modulate a carrier wave. These physical
variables might be the strengths of the synaptic junctions. Pribram
identifies the dendritic network (a dense set of neural fibers) as the
likely substrate of such a brain process.

This holographic model would appear to be implementable within quantum
electrodynamics, which is the physical theory that would normally be
expected to control brain dynamics. However, Umezawa and co-workers
(Riccardi & Umezawa, 1967; Stuart, Takahashi, & Umezawa, 1978; 1979)
have suggested that an exotic physical process is involved, namely a
process similar to what appears in the theory of superconductively. That
theory is characterized by the existence of a continuum of states of the
same (lowest) energy, and Umezawa has suggested that long-term memory is
associated with the breaking the symmetry of these ground states,
instead of, for example, enduring changes in the physical structures of
nerve cells.

Jibu and Yasue (Jibu 1995) have attempted to weave these ideas of
Pribram and Umezawa into a unified quantum theory of brain dynamics
(QBD). Their theory takes the substrate associated with Umezawa's ideas
to be the water that pervades the brain. Excitations of certain states
of the water system are called corticons, and they interact with photons
in the electromagnetic fields of, for example, the dendritic network.
They say:

*"With the help of quantum field theory, we have found that the creation
and annihilation dynamics of corticons and photons in the QBD system in
the sub-microscopic world of the brain to be the entity we call
consciousness or mind."*

However, they have not made clear why "the creation and annihilation
dynamics of corticon and photons" should possess the defining
characteristics of conscious processes, namely the fact that they are
"feelings": Conscious experiences have a quality of "feelingness" about
them that is not contained in, or entailed by, the physical concepts of
corticons and photons, or of the dynamics of these entities that they
claim "*to be the entity we call consciousness or mind."* Thus their
work does not address the basic question of how rationally to get the
concepts that characterize the experiential aspects of reality out of
the concepts of the physical theory. That question is the one that was
answered by the work of von Neumann, and that has been the primary focus
of this entry.

**GLOSSARY**

**Quantum Jumps.** The "mystery of quantum theory" is concentrated
wholly in the peculiarities of the quantum jumps, which seem to have
both subjective experiential aspects associated with "increases in
knowledge" and also objective physical aspects associated with changes
in the expectations or potentialities for future quantum jumps. In the
chapter "The Copenhagen Interpretation" in his book "Physics and
Philosophy", Heisenberg (1958b, p.54) says "When the old adage \`*natura
non facit saltus'* (nature makes no jumps), is used as a basis for
criticism of quantum theory, we can reply that certainly our knowledge
can change suddenly and that this fact justifies the use of the term
\`quantum jump'". This explanation stresses the subjective/experiential
knowledge-increasing aspect of the quantum jumps, and is very much in
line with the words of Bohr. But Heisenberg then begins a further
discourse with the words "If we want to know what happens in an atomic
event". He then speaks of "the transition from 'possible' to 'actual'
that takes place as soon as the interaction of the object with the
measuring device, and hence with the rest of the world, comes into
play." He says that this transition from \`possible' to \`actual' is "is
not connected to the registration of the result in the mind of the
observer", but that "the discontinuous change in *the probability
function,* however, takes place with the act of registration, because it
is the discontinuous change of our knowledge in the instant of
registration that has its image in the discontinuous change in the
probability function." In this account there are two different kinds of
jumps, one purely physical, and occurring at the device, and one purely
psychological/experiential, and occurring in the mind of the observer.
The idea is that the probability function is a mathematical construct
that lives in the minds of human scientists, and represents "our
knowledge", and that it consequently "jumps" when our knowledge
increases. There are also physical jumps that occur at the devices. But
what happens in a person's *brain* when an abrupt increase in his
knowledge occurs? A brain is similar in many ways to a measuring device:
there is energy available to magnify quickly the effects some small
triggering event. And how does one explain the fantastic accuracy of
quantum calculations if the quantum mathematics that exists in our minds
is not closely related to what is really happening? The von Neumann
formulation answers these questions by shifting the boundary between the
observed system and the observer so that the physically described state
includes the brain of the observer, and the two kinds of "jumps"
described by Heisenberg become two aspects of a single kind of quantum
jump that occurs at the mind-brain interface. Von Neumann's Process
**1** is the physical aspect of the choice on the part of the human
agent. Its psychologically described aspect is experienced and described
as a focusing of attention and effort on some intention, and the
physically described aspect consists of the associated choice of the
basis vectors and of the timings of the action. Then there is a feedback
quantum jump whose psychologically described aspect is experienced and
described as an increment in knowledge, and whose physical aspect is a
"quantum jump" to a new physical state that is compatible with that
increment in knowledge. Thus the two aspects of the conceptual
foundation of science, the objective/mathematical and the
subjective/experiential, are linked together, *within the theory*, in
the conceptual structure of the quantum jump.

**Planck's Constant.** This number, discovered by Max Planck in 1900, is
a number that characterizes quantum phenomena. It specifies a definite
connection between energy and frequency. The energy carried by a quantum
entity, such as an electron or photon (a quantum of "light"), divided by
Planck's constant, defines a "frequency" (the number of oscillations per
second) that is associated with this entity. Thus Planck's constant
links together a discrete "lump" or "quantum" of energy with an
oscillatory motion of specified frequency. This constant thus forms the
basis for linking a property normally associated with a "particle",
namely a discrete amount of energy, with a property that is associated
in quantum theory with a wave motion. In classically describable
phenomena the products of energy and frequency of the individual quantum
entities that combine to produce the macroscopic phenomena is so small
on the scale of observable parameters as to be individually
undetectable, even though the macroscopically measurable properties of
materials depend strongly upon the quantum properties of their
constituent elements.

**Quantum Zeno Effect.** The equations of motion of a quantum system
differ in many ways from the classical equations. One such way is this:
The motion of a planet, as described by Kepler's empirical laws, and by
Newton's theoretical ones, are such that the motion does not depend on
how often we look at it. But the evolution in time of an observed
quantum system depends on Process **1**, which is specified in the
theory by observational choices made by the experimenter/observer/agent.
In the case of a planet the effect of our observations are negligible.
But experiments on atoms (Itano, Heinzen, Bollinger, and Wineland, 1990)
show that the behavior of atoms can be strongly affected by the rapidity
at which Process **1** events are occurring. If these events occur
sufficiently rapidly then the normal behavior of the atom, such as a
transition from an excited state to a state of lower energy, is slowed
down. This was predicted by quantum theory, and the empirical results
are in good agreement with theoretical predictions. This slowing effect
is called the Quantum Zeno Effect. (Misra and Sudarshan, 1977). If the
observed system is the brain of an agent then, as a consequence of
evolutionary and educational processing, this brain could be expected to
become very sensitive to variations in the character of the Process
**1** events. This is because "Templates for Action" could be held in
place longer than normal by "free" choices made agents, and this could
strongly influence behavior. Such an effect would elevate the choices
made by human agents from their status in classical physics as
mechanically determined epiphenomenal side effects to causes that, *in
principle*, are not fully traceable within contemporary physical theory
to purely physical processes, and hence are properly treatable as
empirical inputs.

**Template for Action.** This is an "executive" patterns of neurological
activity that if held in place for an extended period will issue the
sequence of neural signals that will initiate and monitor a particular
physical (or perhaps mental) action.

**Gödel's Incompleteness Theorem. "**Any finite set of rules that
encompass the rules of arithmetic is either inconsistent or incomplete:
it entails either statements that can be proved to be both true and
false, or statements that cannot be proved to be either true or false."

**Heisenberg's Uncertainty Principle.** This principle asserts the
mathematical fact that within the logical framework provided by quantum
theory the position and momentum (velocity times mass) of a quantum
entity cannot be simultaneously defined to arbitrary accuracy. The
product of the uncertainties in these two quantities is given by
Planck's constant. This principle renders the classical concept of the
deterministic motions of the planets in the solar system inapplicable to
the motions of the ions in a human brain.

REFERENCES

Beck, F. & Eccles, J. (2003). Quantum Processes in the Brain: A
scientific basis of consciousness. In N. Osaka (Ed.), *Neural Basis of
Consciousness*. Amsterdam, Philadelphia: John Benjamins. p. 141-166.

Bell, J. S. (1964). On the Einstein-Podolsky-Rosen paradox. *Physics* 1
195-200.

Bohm, D. (1952). A suggested interpretation of quantum theory in terms
of hidden variables. *Physical Review,* 85, 166-179.

Bohm, D. J. (1986). A new theory of the relationship of mind to matter.
*The Journal of the American Society for Psychical Research,*

80, 113-135.

Bohm, D. J. (1990). A new theory of the relationship of mind to matter.
*Philosophical Psychology*, 3, 271-286.

Bohm, D, & Hiley, D.J. (1993). *The Undivided Universe.* London and New
York: Routledge.

Bohr, N. (1958). *Atomic Physics and Human Knowledge.* New York: Wiley.

Bohr, N. (1963). *Essays 1958/1962 on* *Atomic Physics and Human
Knowledge.* New York: Wiley.

Eccles, J.C. (1990). A unitary hypothesis of mind-brain interaction in
the cerebral cortex. *Proceedings of the Royal Society of London, B240*,
433-451.

Eccles, J.C. (1994). *How the self controls its brain.* Berlin,
Heidelberg, New York: Springer.

Fogelson, A & Zucker, R, (1985). Presynaptic calcium diffusion from
various arrays of single channels. *Biophysical J*. 48 1003-1017.

Hagen, S., Hameroff, S, & Tuszynski, J. (2002). Quantum computation in
brain microtules: Decoherence and biological feasibility. *Physical
Review* E65, 061901-1 -- 061901-11.

Hameroff, S. & Penrose, R. (1996). Orchestrated reduction of quantum
coherence in brain microtubules: a model for consciousness. *J.
Consciousness Studies* 3, 36-53.

Heisenberg, W. (1958a). The representation of Nature in contemporary
physics. *Daedalus* 87, 95-108.

Heisenberg, W. (1958b). *Physics and Philosophy*. New York: Harper,

Itano, A, Heinzen, D., Bollinger, j., and Wineland, D. (1990). Quantum
Zeno effect. .*Physical Review* A41, 2295-2300.

James, W. (1890) *The principles of psychology Vol. II*. New York:
Dover.

James, W. (1892) *Psychology: The briefer course*. In *William James:
Writings 1879-1899*. New York: Library of America (1992).

Jibu, M. & Yasue, K. (1995). Quantum brain dynamics and consciousness.
Amsterdam and Philadelphia: John Benjamins.

Libet, B (1985). Unconscious cerebral initiative and the role of
conscious will in voluntary action. *Behavioural & Brain Sciences*, 8,
529-566.

Libet, B. (2003). Cerebral physiology of conscious experience:
Experimental Studies. In N. Osaka (Ed.), *Neural Basis of
Consciousness*. \[Advances in consciousness research series, 49\]
Amsterdam & New York: John Benjamins.

Misra, B. & Sudarshan, E.C.G. (1977). The Zeno's paradox in quantum
theory. *Journal of Mathematical Phys*ics 18: 756-763.

Ochsner, K.N. & Silvia A. Bunge, James J. Gross, and John D.Gabrieli
(2002). Rethinking feelings: An fMRI study of the cognitive regulation
of emotion. *J. Of Cognitive Neuroscience,* 14:8, 1215-1229.

Pashler, H. (1998). *The psychology of attention*. Cambridge, MA: MIT
Press.

Penrose, R. (1986). *The emperor's new mind*. New York: Oxford.

Penrose, R. (1994). *Shadows of the mind*. New York: Oxford.

Putnam, H. (1994). Review of Roger Penrose, Shadows of the Mind,

*New York Times Book Review*, November 20, p.7. Reprinted in AMS
bulletin:

[www.ams.org/journals/bull/pre-1996data/199507/199507015.tex.html](http://www.ams.org/journals/bull/pre-1996data/199507/199507015.tex.html)

Pribram, K. H. (1966). Some dimensions of remembering: Steps towards a
neurophysiological theory of memory. In J. Gaito (Ed.), *Macromolecules
and behavior*, (pp. 165-187) New York, NY: Academic Press.

Pribram, K. H. (1991). *Brain* *and Perception*. New Jersey: Lawrence
Erlbaum.

Riccardi, L.M. & Umezawa, H. (1967). Brain and physics of many-body
problems. *Kybernetik* 4, 44-48.

Schwartz, J. & Begley, S. (2002). *The mind and the brain:
neuroplasticity and the power of mental force*. New York:
Harper-Collins.

Schwartz, J., Stapp, H. & Beauregard, M (2003). The volitional influence
of the mind on the brain, with special reference to emotional self
regulation. In M. Beauregard (Ed.), *Consciousness, Emotional
Self-Regulation and the Brain*. \[Advances in Consciousness Research
Series\]. Amsterdam & New York: John Benjamins.

Stapp, H. (1999). Attention, intention, and will in quantum physics. J.
Consciousness Studies, 6, 143-164.

Stapp, H. (2001). Quantum theory and the role of mind in Nature. *Found.
Phys*. 31, 1465-1499.

Stuart, C.I.J.M., Takahashi, Y., & Umezawa, H. (1978). On the stability
and nonlocal properties of memory. *Journal of theoretical biology*, 71,
605-618.

Stuart, C.I.J.M,, Takahashi, Y., & Umezawa, H. (1979). Mixed-system
brain dynamics: neural memory as a macroscopic ordered state.
*Foundations of Physics* 9, 301-327.

Tegmark, M. (2000). Importance of quantum decoherence in brain process.
*Physical Review* E61, 4194-4206.

Von Neumann, J. (1955/1932). *Mathematical Foundations of Quantum
Mechanics.* Princeton: Princeton University Press. (Translated by Robert
T. Beyer from the 1932 German original, Mathematiche Grundlagen der
Quantummechanik. Berlin: J. Springer)