**7. KNOWLEDGE OR POTENTIA.**

The original \"Copenhagen\" approach took quantum theory to be a
practical tool that allows scientists to form, on the basis of past
experiences, reliable expectations about future ones. The reality
described by that theory was \"our knowledge\", and inquiry into the
nature of the reality in which this knowledge is imbedded was
discouraged. However, human beings are an inquisitive lot, and even
Heisenberg was not immune to the disease of wanting to know more than
one\'s philosophy allows.

The success of a theory that allows empirically measured numbers to be
computed to an accuracy of one part in a hundred million says a lot
about the reality. It rules out a host of possibilities, and places
stringent conditions on the rest. Thus an understanding of the structure
this immensely successful theory permits reasonable conjectures to be
advanced about the nature of the whole of which our experiences are but
a tiny a part.

Heisenberg in his 1958 book Physics and Philosophy allowed himself to
speculate on the nature of the reality lying behind our streams of
conscious thoughts. He ties his idea of Nature to the Aristotelian idea
of \"potentia\", which is an objective tendency for some particular
thing to happen. Each such \`happening\' is a transition from
\`possible\' to \`actual\'.

Heisenberg\'s conjecture is compactly summarized in his statement:

\"If we want to describe what happens in an atomic event we have to
realize that the word \`happens\' ... applies to the physical not the
psychical act of observation, and we may say that the transition from
the \`possible\' to the \`actual\' takes place as soon as the
interaction between the \[atomic\] object and the measuring device, and
thereby with the rest of the world, has come into play: it is not
connected with the act of registration of the result in the mind of the
observer. The discontinuous change in the probability function, however,
takes place with the act of registration, because it is the
discontinuous change in our knowledge at the moment of registration that
has its image in the discontinuous change in the probability function.\"

\[Physics and Philosophy, Harper and Rowe, New York, 1958, p.54\]

At first sight this passage seems self-contradictory: it says that the
sudden change occurs at the device, not in the mind, and then says that
it occurs in the mind. But there is no contradiction. The sudden change
when the interaction between object and device comes into play refers to
the transition from the \`possible\' to the \`actual\', which is what
happens physically, but about which Copenhagen quantum theory officially
says nothing, whereas the probability function is what quantum theory
deals with, and it changes when our knowledge changes. Thus Heisenberg,
by this two-level description, one dealing with physical reality, the
other with psychological reality, reconciles the Copenhagen viewpoint
with our desire to understand what is really going on.

This idea that some real event actually occurs when the interaction
between object and measuring device comes into play accords well with
the quantum mathematical description. One can believe that the quantum
state in the mind of the physicist is a mental image of an external (to
human minds) mathematical reality that corresponds to a potentia, or set
of objective tendencies, for the physical device to respond in each of
its alternative possible modes. These objective tendencies can be
measured by the relative frequencies of the various alternative possible
outcomes. This idea of the connection between probability and reality is
called \"the propensity interpretation of probabilities\", and it
immediately gives an objective picture of a physical reality that
accounts in a natural way for the success of the Copenhagen rules
pertaining to our knowledge of that reality.

The \"potentia\" for the occurrence of some particular one of a set of
mutually exclusive alternative possibilities naturally drops to zero
when another one of the set of possibilities actually happens. So this
model, based on the idea that physical reality is made out of
potentialities, or objective tendencies, allows the faster-than-light
effects to be understood as the instantaneous change in the real
objective potentialities that constitute the physical world when one of
the alternative possibilities is actualized.

Heisenberg thus refers in this single passage to two different possible
ways of understanding nature, one based on the speculative notion of
objective physical tendencies, the other on the more secure idea of
subjective psychological realities.

**8.SYNTHESIS.**

John von Neumann is one of the premier minds of the twentieth century. A
renowned mathematician and logician, he was also a principal creator of
the concepts of the modern computer. In his 1932 book *The Mathematical
Principles of Quantum Mechanics* he placed that theory on a firm
mathematical foundation, and examined also the delicate issues
associated with the role of the conscious observer. The original
Copenhagen treatment of the observer relied heavily on the pragmatic
premise that problems that do not intrude significantly into practical
applications can be ignored.

If one seeks to go beyond merely a set of rules that work for us, and
propound a rationally coherent conception of the reality in which our
human experiences are imbedded, then the faster-than-light problem must
be dealt with in some way. Heisenberg\'s idea of a world of
\"potentialities\" is the most parsimonious possibility: it brings in no
needless entities, except for the doubling of actual events: there are
both physical events associated with the transitions from possible to
actual, and also the psychological events, which occur in the mind of
the observer. To make a cohesive theory a connection is needed between
the physically described ontology (theory of what exists) and the
psychologically described epistemology (theory of what we know).

The need for this bridge leads to the technical problem of what defines
the \"devices\" where the transitions from possible to actual are
supposed to occur. Micro-fabrication techniques allow extremely tiny
device-like structures to be built. Their behaviors are probed by bigger
devices etc., and the nerve cells with receptors in the retina can also
be regarded as measuring devices, as can higher-level brain structures.
The quantum rules allow all of these structures to be represented in
principle as quantum systems. Yet in a more precise sense none of them
can. For each such system is imbedded in a larger whole from which it
cannot be disentangled within the mathematical quantum framework. The
only physical system that is strictly describable within quantum theory
is the entire universe.

Von Neumann bit the bullet. He showed how the validated predictions of
quantum theory, which were based on the idea of restricting the quantum
system to the small system being probed by the measuring device, could
be preserved and understood by expanding the quantum system to include
the entire universe, including the complete brains of all the observers,
provided he identified the physical events as brain events that
actualize the neural correlates of an associated psychological event.
This identification of the subjective experience upon which Copenhagen
formulation of quantum theory is based as an aspect of the physical
brain event that actualizes the pattern of brain activity that
corresponds to that psychological experience synthesizes the two
interpretations offered by Heisenberg, and it establishes a close
natural correspondence the two parts of nature that Rene Descartes put
asunder. It places the experiences that are the realities upon which the
Copenhagen interpretation rests into the physical world of
potentialities that Heisenberg identified as external reality that is
the carrier of the real \"happenings.\" This identification of, or
association of, experiential events with quantum brain events
establishes a direct mathematically defined causal linkage between the
experiential and physical aspects of Nature. It repairs the terrible
damage inflicted on natural and moral philosophy by the followers of
Descartes. (Descartes himself allowed these two aspects of nature to
interact within brains, in accordance with intuition, common sense, and
quantum theory, but the mechanical dynamical completeness of classical
physical theory seemed to forbid any kind of interaction between these
two so differently conceived kinds of reality. However, the freedom
given to experimental agents by the quantum laws rehabilitates Descartes
original position.)

This solution is perhaps a quantum version of the \"identity theory\"
solution of the mind-brain problem in classical physics. However, here
it arises from a natural synthesis of two incomplete theories that each
separately require events that the synthesis amalgamates. The important
difference, however, is that this psychophysical event is not just a
passive automatic consequence of the micro-causal deterministic
evolution specified by the Schroedinger equation, which is the quantum
analog of the classical laws of motion. There is an element of freedom
that lies beyond the compass of the known laws of nature. A second
process is needed to complete the dynamics. This is the \"twenty
questions\" procedure, which involves first a free choice of question
posed by the actor/observer, and then a statistically governed answer
delivered by nature. In von Neumann\'s step-by-step passage from the
Copenhagen version of quantum theory to the final synthesis, the
psychologically described actor/observer always retains the function of
freely choosing which question to be put to nature, and this freedom
persists in the limit. This freedom associated with the second process,
which von Neumann calls Process I, must be retained in the limit because
the questions must get posed for the dynamics to work, and the discrete
questions cannot be naturally selected by the continuous dynamics. The
question thus naturally arises: To what extent can this very limited
freedom, granted to the human actors, to pose questions, be used to
influence that person\'s mental process, and hence bodily behavior?

**9. THE EFFICACY OF MENTAL EFFORT.**

We feel innately that our thoughts themselves actually do things: that
they influence our succeeding thoughts and actions; that our felt mental
effort is actually causing our muscles to bulge as we strain to budge
our trapped vehicle.

Classical physics tells us that this most deeply felt of all our
convictions, and the basis of all our mental actions, is shear
poppy-cock; a queer illusions that besets our addled mind. Brain does it
all, we are told, and our thoughts and feeling are but some ineffectual
supernumeraries, or nothing beyond the functional complex patterns of
motion of tiny atomic particles.

But if common sense be any guide then our thoughts and feelings must be
doing something that our classically conceived brains alone cannot do as
well. For why else would nature produce, in addition to the motions of
the particles, such realities as feelings and ideas. And how could these
logically unnecessary and disjoint supernumeraries evolve if they
*themselves* contribute nothing to our fitness.

Quantum theory provides a natural place for our thoughts, and an
essential dynamical role for them to play. Our psychologically described
essence does what our physically described brains alone cannot do: it
selects the questions associated with the crucial collapse process. This
latter process actualizes certain of the potentialities that inhere in
the quantum state of the brain, and that are carried forward in time by
the Schroedinger equation of motion. That physically described evolution
creates multiple continua of potentialities but cannot actualize any one
of them.

The actualization procedure is a two-step operation. First a specific
question must be selected. This choice must be rooted in the
psychologically described aspect, because making a discrete choice of
question, represented by a specific projection operator P, lies beyond
the capacity of amorphous continuum of potentialities represented by the
state vector V: it cannot discriminate one set of N perpendicular
vectors from others differing only infinitesimally from the first set.
Given the selected question, nature delivers her answer, which is both
psychologically experienced and etched in the brain structure by the
quantum collapse VPV. This model of the mind-brain connection provides
a contemporary-science-based alternative to the classical-physics-based
model.

In this model the dynamical role of consciousness is extremely
restricted: it can do nothing but influence the choices of questions
associated with von Neumann\'s process **I**. That severe restriction
is, in fact, what gives the theory its predictive and explanatory power.

But how can the mere selection of questions influence behavior? In
classical physics it could not, since everything is predetermined, and
while asking a question and getting an answer may illuminate the mind of
the passive observer, it cannot actually influence what happens. But in
quantum mechanics the situation is quite different. There is an
important and well-studied effect in quantum theory that depends on the
timings of the reduction events arising from the queries put to nature.
It is called the Quantum Zeno Effect.

The effect is simple. If the same question is put to nature sufficiently
rapidly and the initial answer is Yes, then any noise-induced diffusion,
or force-induced motion, of the system away from the subspace where the
answer is \`Yes\' will be suppressed: the system will tend to be
confined to the part of the Hilbert space where the answer is \`Yes\'.
The effect is sometimes called the \`\`watched pot\'\' effect: according
to the old adage \`\`A watched pot never boils\'\'; just looking at it
keeps it from changing. Also, a state can be pulled along in some
direction by posing a rapid sequence of questions that change
sufficiently slowly over time. In short, according to the dynamical laws
of quantum mechanics, the freedom to choose which questions are put to
nature, and when they are asked, could allow mind to influence the
behavior of the brain. However, the effect is extremely limited: it is
merely the tendency to hold in place the focus of mental attention. The
drift in attention that would normally arise from quantum uncertainties,
noise, and even ordinary forces, is held in check by incessant probing.

A person is aware of almost none of the processing that is going on in
his brain: unconscious brain action does almost everything. So it would
be both physically unrealistic and theoretically unfeasible to give mind
unbridled freedom: the questions posed by mind ought to be determined in
large measure by the brain itself.

But then what freedom is given to mind?

According to quantum theory, the freedom given to Nature herself is
merely to provide Yes or No answers to questions posed by subsystems. It
seems reasonable to restrict in a similar way the freedom given to human
minds.

It is easy to construct a simple dynamical model in which the brain does
most of the work, and the mind, merely by means of choices of whether or
not pose the question presented by the brain, influences the course of
mental\-\--hence also bodily\-\--action.

Consider the set of projection operators P that act only on the brain of
some individual, and that correspond to possible mental events of that
individual. Quantum theory assigns a probability to each such P at each
instant of time t. Consider at each time t the P that has the greatest
probability. It represents the \`\`best possible\'\' question to ask at
that moment: it has accumulated the greatest statistical weight. Suppose
that when the probability associated with this possible event reaches a
maximum the associated question \"shall the possible experience
associated with P be actualized?\" is put to nature. If nature returns
the answer \`Yes\', then the transition VPV occurs, along with the
associated experience. The new dynamical postulate is that the \"feel\"
of this event can activate an \"effort\" that can instigate a sequence
of posings of this same question that is rapid on the time scale of the
evolution of PV. The dynamical rules of quantum theory then ensure that
the rapid-fire posings of this question will keep the brain in the
subspace associated with the answer Yes.

If a process like this operates then the course of brain and body events
would be influenced by the effort produced by the \"feel\" of mental
events.

The Quantum Zeno Effect will not freeze up the brain completely. It
merely keeps the state of the brain in the subspace where attention is
focussed on a particular idea.

Does this theory of the connection between mind and brain explain
anything?

Essentially this model was already in place when a colleague, Dr.
Jeffrey Schwartz, brought to my attention some passages from
\`\`Psychology: The Briefer Course\'\', written by William James. In the
final section of the chapter on Attention James writes:

\`\`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 introduce no new idea, it

will deepen and prolong the stay in consciousness

of innumerable ideas which else would fade more

quickly away. The delay thus gained might not be

more than a second in duration\-\--but that second

may be critical; for in the rising and falling

considerations in the mind, where two associated

systems of them are nearly in equilibrium it is

often a matter of but a second more or less of

attention at the outset, whether one system shall

gain force to occupy the field and develop

itself and exclude the other, or be excluded

itself by the other. When developed it may

make us act, and that act may seal our doom.

When we come to the chapter on the Will

we shall see that the whole drama of the

voluntary life hinges on the attention, slightly

more or slightly less, which rival motor

ideas may receive. \...\'\'

In the chapter on Will, in the section entitled

\`\`Volitional effort is effort of attention\'\'

James writes:

\`\`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.\'\'

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:

\`\`Consent to the idea\'s undivided presence,

this is effort\'s sole achievement.\'\'\...

\`\`Everywhere, then, the function of effort is

the same: to keep affirming and adopting the

thought which, if left to itself, would slip away.\'\'

This description of the effect of mind on the

course of mind-brain process is remarkably

in line with what had been proposed independently

from purely theoretical consideration of the

quantum physics of this process. The connections

specified by James are explained on the basis of

the same dynamical principles that had been

introduced by physicists to explain atomic

phenomena. Thus the whole range of science,

from atomic physics to mind-brain dynamics, is

brought together in a single rationally coherent

theory of an evolving cosmos that consists of a

physical reality that is constituted not of matter

but of potentia for events to occur. And these

events include, but are certainly not restricted to,

collapses to reduced states that bring this physical

reality into accord with the increments of human

knowledge that pragmatic quantum theory

is based upon.

Much experimental work on attention and effort has occurred since the
time of William James. That work has been hampered by the apparent
nonexistence of any physical theory that rationally explains how our
conscious experiences could influence activities in our brains. The
behaviorist approach, which dominated psychological during the first
half of the twentieth century, and which essentially abolished in this
field the use not only of introspective data but also of the very
concept of consciousness, was surely motivated in part by the fact that
consciousness was excluded from any role in brain dynamics by the
physics of the preceding century

The failure of the behaviorist programs led to the rehabilitation of
\`\`attention\'\' during the early fifties, and many hundreds of
experiments have been performed during the past fifty years for the
purpose of investigating empirically those aspects of human behavior
that we ordinarily link to our consciousness.

Harold Pashler\'s 1998 book \`\`The Psychology of Attention\'\' \[32\]
describes a great deal of this empirical work, and also the intertwined
theoretical efforts to understand the nature of an
information-processing system that could account for the intricate
details of the objective data. Two key concepts are the notions
\`\`Attention\'\' and of a processing \`\`Capacity\'\'. The former is
associated with an internally directed selection between different
possible allocations of the available processing \`\`Capacity\'\'. A
third concept is \'\'Effort\'\', which is linked to incentives, and to
reports by subjects of \`\`trying harder\'\'.

Pashler organizes his discussion by separating perceptual processing
from post-perceptual processing. The former covers processing that,
first of all, identifies such basic physical 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 actions and cognitive action 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 \[p. 33, 263, 293, 317, 404\].

In the quantum theory of mind-brain being described here there are two
separate processes. First, there is the unconscious mechanical brain
process governed by the Schroedinger equation. As discussed at length in
my earlier book, Mind, Matter, and Quantum Mechanics, this brain
processing involves dynamical units that are represented by complex
patterns of neural activity (or, more generally, of brain activity) that
are \`\`facilitated\'\' by use, and such that each unit tends to be
activated as a whole by the activation of several of its parts. The
activation of various of these complex patterns by cross referencing,
coupled to feed-back loops that strengthen or weaken the activities of
appropriate processing centers, seems to explain the essential features
of the mechanical part of the dynamics.

The function of the brain is to create and direct courses of action
appropriate to the circumstances in which the organism finds itself.
Accordingly, the brain ought to create a template for a possible plan of
action. Detailed examination of the quantum uncertainties associated the
motion in nerve terminals of incoming calcium ions from the ion channels
to the triggering sites for the release of vesicles of neurotransmitter
entail \[MM&QM, p.152\] that a host of different possibilities will
emerge. This mechanical phase of the processing already involves some
selectivity, because of the enhancing and inhibiting feedback loops. But
the essential point is that the evolution of the brain according to the
Schroedinger equation *must* generate not just one single template for
action, but a host of alternative possibilities. Hence the action of the
second process, von Neumann\'s Process **I** must come into play in
order to select what actually happens from the continuum of alternative
possibilities generated by the mechanical aspect of the full quantum
dynamics. But Process **I** involves the element of freedom that feeds
into the Quantum Zeno Effect.

This conception of brain dynamics seems to accommodate all of the
perceptual aspects of the data described by Pashler. But it is the
high-level processing, which is more closely linked to our active
mentally controlled conscious thinking, that is of prime interest here.
The data pertaining to this second process is the focus of part II of
Pashler\'s book.

Mental intervention has, according to the quantum-physics-based theory
described here, several distinctive characteristics. It consists of a
sequence of discrete events each of which consents to an integrated
course of action presented by brain. The rapidity of these events can be
increased with effort. Effort-induced speed-up of the rate of occurrence
of these events can, by means of the quantum Zeno effect, keep attention
focussed on a task. Between 100 and 300 msec of consent seem to be
needed to fix a plan of action.

Effort can, by increasing the number of events per second, increase the
mental input into brain activity. Each conscious event picks out from
the multitude of quasi-classical possibilities that comprise the quantum
brain the sub-ensemble that is compatible with the conscious experience.

The correspondence between the mental event and the associated physical
event is this: the physical event reduces the prior physical ensemble of
alternative possibilities to the sub-ensemble compatible with the mental
event. This connection constitutes the core postulate of Copenhagen
quantum theory: the physical event reduces the prior state of the system
to the part of it that is compatible with the experience of the
observer.

Examination of Pashler\'s book shows that this quantum-physics-based
theory accommodates naturally all of the complex structural features of
the empirical data that he describes. He emphasizes \[p. 33\] a specific
finding: strong empirical evidence for what he calls a central
processing bottleneck associated with the attentive selection of a motor
action. This kind of bottleneck is what the quantum-physics-based theory
predicts: the bottleneck is precisely the single linear sequence of
mind-brain quantum events that von Neumann quantum theory is built upon.

Pashler \[p. 279\] describes four empirical signatures for this kind of
bottleneck, and describes the experimental confirmation of each of them.
Much of part II of Pashler\'s book is a massing of evidence that
supports the existence of a central process of this general kind.

This bottleneck is not automatic within classical physics. A classical
model could easily produce simultaneously two responses in different
modalities, say vocal and manual, to two different stimuli arriving via
two different modalities, say auditory and tactile. The two processes
could proceed via dynamically independent routes. Pashler \[p. 308\]
notes that the bottleneck is undiminished in split-brain patients
performing two tasks that, at the level of input and output, seem to be
confined to different hemispheres.

The queuing effect for the mind-controlled motor responses does not
exclude interference between brain processes that are similar to each
other, and hence that use common brain mechanisms. Pashler \[p. 297\]
notes this distinction, and says \`\`the principles governing queuing
seem indifferent to neural overlap of any sort studied so far.\'\'

The important point here is that there is in principle, in the quantum
model, an essential dynamical difference between, on the one hand, the
unconscious processing carried out by the Schroedinger evolution, which
generates via a local process an expanding collection of classically
implementable possible courses of action, and, on the other hand, the
process associated with the sequence of conscious events that
constitutes a stream of consciousness. The former are not limited by the
queuing effect, because all of the possibilities develop in parallel,
whereas the latter do form elements of a single queue. The experiments
cited by Pashler all appear to support this clear prediction of the
quantum approach.

An interesting experiment mentioned by Pashler involves the simultaneous
tasks of doing an IQ test and giving a foot response to a rapidly
presented sequences of tones of either 2000 or 250 Hz. The subject\'s
mental age, as measured by the IQ test, was reduced from adult to 8
years. \[p. 299\] This result supports the prediction of quantum theory
that the bottleneck pertains both to \`intelligent\' behavior, which
requires conscious processing, and to selection of motor response.

Another interesting experiment showed that, when performing at maximum
speed, with fixed accuracy, subjects produced responses at the same rate
whether performing one task or two simultaneously: the limited capacity
to produce responses can be divided between two simultaneously performed
tasks. \[p. 301\]

Pashler also notes \[p. 348\] that \`\`Recent results strengthen the
case for central interference even further, concluding that memory
retrieval is subject to the same discrete processing bottleneck that
prevents simultaneous response selection in two speeded choice
tasks.\'\'

In the section on \`\`Mental Effort\'\' Pashler reports that
\`\`incentives to perform especially well lead subjects to improve both
speed and accuracy\'\', and that the motivation had \`\`greater effects
on the more cognitively complex activity\'\'. This is what would be
expected if incentives lead to effort that produces increased rapidity
of the events, each of which injects into the physical process, via
quantum selection and reduction, bits of control information that
reflect mental evaluation.

Studies of sleep-deprived subjects suggest that in these cases
\`\`effort works to counteract low arousal\'\'. If arousal is
essentially the rate of occurrence of conscious events then this result
is what the quantum model would predict.

Pashler notes that \`\`Performing two tasks at the same time, for
example, almost invariably\... produces poorer performance in a task and
increases ratings in effortfulness.\'\' And \`\`Increasing the rate at
which events occur in experimenter-paced tasks often increases effort
ratings without affecting performance\'\'. \`\`Increasing incentives
often raises workload ratings and performance at the same time.\'\' All
of these empirical connections are in line with the general principle
that effort increases the rate of conscious events, each of which inputs
a mental evaluation and a selection or focussing on a course of action,
and that this resource can be divided between tasks.

Additional supporting evidence comes from the studies of the effect of
the conscious process upon the storage of information in short-term
memory. According to the physics-based theory, the conscious process
merely actualizes a course of action, which then develops automatically,
with perhaps some occasional monitoring. Thus if one sets in place the
activity of retaining in memory a certain sequence of stimuli, then this
activity can persist undiminished while the central processor is engaged
in another task. This is what the data indicate.

Pashler remarks that \'\'These conclusions contradict the remarkably
widespread assumption that short-term memory capacity can be equated
with, or used as a measure of, central resources.\'\'\[p.341\] In the
theory outlined here short-term memory is stored in patterns of brain
activity, whereas consciousness is associated with the selection of a
sub-ensemble of quasi-classical states. This distinction seems to
account for the large amount of detailed data that bears on this
question of the connection of short-term-memory to consciousness.
\[p.337-341\]

Deliberate storage in, or retrieval from, long-term memory requires
focussed attention, and hence conscious effort. These processes should,
according to the theory, use part of the limited processing capacity,
and hence be detrimentally affected by a competing task that makes
sufficient concurrent demands on the central resources. On the other
hand, \`\`perceptual\'\' processing that involves conceptual
categorization and identification without conscious awareness should not
interfere with tasks that do consume central processing capacity. These
expectations are what the evidence appears to confirm: \`\`the entirety
of\...front-end processing are modality specific and operate independent
of the sort of single-channel central processing that limits retrieval
and the control of action. This includes not only perceptual analysis
but also storage in STM (short term memory) and whatever may feed back
to change the allocation of perceptual attention itself.\'\' \[p. 353\]

Pashler describes a result dating from the nineteenth century: mental
exertion reduces the amount of physical force that a person can apply.
He notes that \`\`This puzzling phenomena remains unexplained.\'\' \[p.
387\]. However, it is an automatic consequence of the physics-based
theory: creating physical force by muscle contraction requires an effort
that opposes the physical tendencies generated by the Schroedinger
equation. This opposing tendency is produced by the quantum Zeno effect,
and 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.

Pashler speculates on the possibility of a neurophysiological
explanation of the facts he describes, but notes that the parallel
versus serial distinction between the two mechanisms leads, in the
classical neurophysiological approach, to the questions of what makes
these two mechanisms so different, and what the connection between them
is. \[p.354-6, 386-7\]

After analyzing various possible mechanisms that could cause the central
bottleneck, Pashler \[p.307-8\] says \`\`the question of why this should
be the case is quite puzzling.\'\' Thus the fact that this bottleneck,
and its basic properties, follow automatically from the same laws that
explain the complex empirical evidence in the fields of classical and
quantum physics means that the theory has significant explanatory power.

Of course, the fact that this theory seems to work so well does not mean
that it is the only theory that can work. But in the past science has
been well served by the endeavor of trying to understand various complex
high-level processes in ways that all fit together coherently with basic
physical theory. The brain is a physio-chemical structure that rests in
principle on quantum processes, and the quantum principles lead in a
completely natural way to a specified kind of dynamical linkage between
the aspects of the mind-brain that are described in psychological and
physical terms. All classically described features are accounted for in
the quantum description, which however provides also a natural dynamical
place for mind whereas classical physics does not.

There is, of course, no empirical evidence that favors the classical
model over the quantum model described above. Quantum theory
automatically accounts for all the successes of classical physical
theory. So all simple physiological and anatomical features of the
physical brain can, according to quantum theory, be treated classically.
The quantum description becomes necessary only when treating subtle
dynamical effects. The effect of mental effort to hold ideas in place
longer than classical computations would predict would seem to be the
most crucial dynamical difference between the classical and quantum
models.

Brain science has suffered through a century of trying to force itself
into a mold it did not fit, namely a now superceded physics that left a
key player out. Ought it not now try just as hard to fit itself into the
framework of the more correct science that explicitly brings in, rather
than denying the existence of, the efficacious thoughts and feelings
that are prima facie features of the structure it studies? And should
not psycho-physics benefit from having a theoretical model that accords
with all physics requirements, yet includes both the psychological and
biological elements it studies, and specifies their ontological and
dynamical relationship to each other. Should not psychology and
psychiatry benefit from having a model of the human being as a
psychologically described agent that interacts with the rest of nature
through his body in specified ways, rather being forced to conceive the
human being as a bundle of cells that behave in wholly mechanical ways
that contradict the basic laws of nature. If basic physical theory was
forced to adopt the realistic view of the human person as a
psychologically described agent why should psychology not follow suit?
Finally, ought not evolutionary biology benefit from allowing human
person\'s to have efficacious minds that can contribute to their
fitness, and thus naturally evolve in step with their physical carriers?