http://www-physics.lbl.gov/~stapp/PTRS.pdf
Review
Quantum physics in neuroscience and psychology:
a neurophysical model of mind–brain interaction
Jeffrey M. Schwartz
1, Henry P. Stapp2 and Mario Beauregard3,4,5,*
1
UCLA Neuropsychiatric Institute, 760 Westwood Plaza, NPI Los Angeles, CA 90024-1759, USA
2
Theoretical Physics Mailstop 5104/50A Lawrence Berkeley National Laboratory, University of California,
Berkeley, CA 94720-8162, USA
3
De´partement de Psychologie, Centre de Recherche en Neuropsychologie Expe´rimentale et Cognition
(CERNEC),
4De´partement de Radiologie, and 5Centre de Recherche en Sciences Neurologiques (CRSN),
Universite´ de Montre´al, C.P. 6128, succursale Centre-ille, Montre´al, Que´bec H3C 3J7, Canada
Neuropsychological research on the neural basis of behaviour generally posits that brain mechanisms
will ultimately suffice to explain all psychologically described phenomena. This assumption stems
from the idea that the brain is made up entirely of material particles and fields, and that all causal
mechanisms relevant to neuroscience can therefore be formulated solely in terms of properties of
these elements. Thus, terms having intrinsic mentalistic and/or experiential content (e.g. ‘feeling’,
‘knowing’ and ‘effort’) are not included as primary causal factors. This theoretical restriction is
motivated primarily by ideas about the natural world that have been known to be fundamentally
incorrect for more than three-quarters of a century. Contemporary basic physical theory differs
profoundly from classic physics on the important matter of how the consciousness of human agents
enters into the structure of empirical phenomena. The new principles contradict the older idea that
local mechanical processes alone can account for the structure of all observed empirical data.
Contemporary physical theory brings directly and irreducibly into the overall causal structure certain
psychologically described choices made by human agents about how they will act. This key
development in basic physical theory is applicable to neuroscience, and it provides neuroscientists
and psychologists with an alternative conceptual framework for describing neural processes. Indeed,
owing to certain structural features of ion channels critical to synaptic function, contemporary
physical theory must in principle be used when analysing human brain dynamics. The new
framework, unlike its classic-physics-based predecessor, is erected directly upon, and is compatible
with, the prevailing principles of physics. It is able to represent more adequately than classic concepts
the neuroplastic mechanisms relevant to the growing number of empirical studies of the capacity of
directed attention and mental effort to systematically alter brain function.
Keywords:
mind; consciousness; brain; neuroscience; neuropsychology; quantum mechanics
The only acceptable point of view appears to be the one
that recognizes
both sides of reality—the quantitative
and the qualitative, the physical and the psychical—as
compatible with each other, and can embrace them
simultaneously.
(
Pauli 1955, p. 208)
1. INTRODUCTION
The introduction into neuroscience and neuropsychology
of the extensive use of functional brain
imaging technology has revealed, at the empirical
level, an important causal role of directed attention in
cerebral functioning. The identification of brain areas
involved in a wide variety of information processing
functions concerning learning, memory and various
kinds of symbol manipulation has been the subject of
extensive and intensive investigation (see
Toga &
Mazziotta 2000
). Neuroscientists consequently now
have a reasonably good working knowledge of the role
of a variety of brain areas in the processing of
complex information. But, valuable as these empirical
studies are, they provide only the data for, not the
answer to, the critical question of the causal
relationship between the aspects of empirical studies
that are described in psychological terms and those
that are described in neurophysiological terms. In
most of the cases, investigators simply assume that
measurable-in-principle properties of the brain are
the only factors needed to explain eventually the
processing of the psychologically described information
that occurs in neuropsychological experiments.
This privileging of physically describable
brain mechanisms as the core, and indeed final,
explanatory vehicle for the processing of every kind of
psychologically described data, is the foundational
assumption of almost all contemporary biologically
based cognitive neuroscience.
Phil. Trans. R. Soc. B
doi:10.1098/rstb.2004.1598
Published online
*
Author for correspondence (mario.beauregard@umontreal.ca).
Received
2 June 2004
Accepted
19 October 2004
1
q 2005 The Royal Society
It is becoming increasingly clear, however, that there
is at least one type of information processing and
manipulation that does not readily lend itself to
explanations that assume that all final causes are
subsumed within brain, or more generally, central
nervous system mechanisms. The cases in question are
those in which the conscious act of wilfully altering the
mode by which experiential information is processed
itself changes, in systematic ways, the cerebral mechanisms
used. There is a growing recognition of the
theoretical importance of applying experimental paradigms
that use directed mental effort to produce
systematic and predictable changes in brain function
(e.g.
Beauregard et al. 2001; Ochsner et al. 2002).
These wilfully induced brain changes are generally
accomplished through training in, and the applied use
of, cognitive reattribution and the attentional recontextualization
of conscious experience. Furthermore,
an accelerating number of studies in the
neuroimaging literature significantly support the thesis
that, again, with appropriate training and effort, people
can systematically alter neural circuitry associated with
a variety of mental and physical states that are frankly
pathological (
Schwartz et al. 1996; Schwartz 1998;
Musso
et al. 1999; Paquette et al. 2003). A recent
review of this and the related neurological literature has
coined the term ‘self-directed neuroplasticity’ to serve
as a general description of the principle that focused
training and effort can systematically alter cerebral
function in a predictable and potentially therapeutic
manner (
Schwartz & Begley 2002).
From a theoretical perspective, perhaps the most
important aspect of this line of research is the empirical
support it provides for a new science-based way of
conceptualizing the interface between mind/consciousness
and brain. Until recently, virtually all attempts to
understand the functional activity of the brain have
been based, at least implicitly, on some principles of
classic physics that have been known to be fundamentally
false for three-quarters of a century. According to
the classic conception of the world, all causal connections
between observables are explainable in terms of
mechanical interactions between material realities. But
this restriction on modes of causation is not fully
maintained by the currently applied principles of
physics, which consequently offer an alternative conceptual
foundation for the scientific description and
modelling of the causal structure of self-directed
neuroplasticity.
The advantages for neuroscience and neuropsychology
of using the conceptual framework of
contemporary
physics, as opposed to that of classic
physics, stem from five basic facts. First, terms such
as ‘feeling’, ‘knowing’ and ‘effort’, because they are
intrinsically mentalistic and experiential, cannot be
described exclusively in terms of material structure.
Second, to explain the observable properties of large
physical systems that depend sensitively upon the
behaviours of their atomic constituents, the founders
of contemporary physical theory were led to introduce
explicitly into
the basic causal structure of physics certain
important choices made by human beings about how
they will act. Third, within this altered conceptual
framework these choices are described in mentalistic
(i.e. psychological) language. Fourth, terminology of
precisely this kind is critically necessary for the design
and execution of the experiments in which the data
demonstrating the core phenomena of self-directed
neuroplasticity are acquired and described. Fifth, the
injection of psychologically described choices on the
part of human agents into the causal theoretical
structure can be achieved for experiments in neuroscience
by applying the same mathematical rules that
were developed to account for the structure of
phenomena in the realm of atomic science.
The consequence of these facts is that twentieth
century physics, in contrast to classic physics, provides a
rationally coherent pragmatic framework in which the
psychologically and neurophysiologically described
aspects of the neuroscience experiments mentioned
above are causally related to each other in mathematically
specified ways. Thus, contemporary physics
allows the data from the rapidly emerging field of selfdirected
neuroplasticity to be described and understood
in a way that is more rationally coherent, scientific and
useful than what is permitted by theories in which all
causation is required to be fundamentally mechanical.
To explicate the physics of the interface between
mind/consciousness and the physical brain, we shall in
this article describe in detail how the quantum
mechanically based causal mechanisms work, and
show why it is necessary in principle to advance to
the quantum level to achieve an adequate theory of the
neurophysiology of volitionally directed activity. The
reason, essentially, is that classic physics is an approximation
to the more accurate quantum theory, and that
this classic approximation
eliminates the causal efficacy of
our conscious efforts
that these experiments empirically
manifest.
We shall also explain how certain structural features
of ion conductance channels critical to synaptic
function
entail that the classic approximation fails in
principle to cover the dynamics of a human brain.
Quantum dynamics
must be used in principle. Furthermore,
once the transition to the quantum description is
made, the principles of quantum theory must, in order
to maintain rational consistency and coherency, be
used to link the quantum physical description of the
subject’s brain to their stream of conscious experiences.
The conscious choices by human agents thereby
become injected non-trivially into the causal interpretation
of neuroscience and neuropsychology experiments.
This caveat particularly applies to those
experimental paradigms in which human subjects are
required to perform decision-making or attentionfocusing
tasks that require conscious effort.
2. PRACTICAL RAMIFICATIONS OF THE
ALTERED CONCEPT OF THE CAUSAL
STRUCTURE OF SELF-DIRECTED
NEUROPLASTICITY
Clarity is required about the sorts of neuroscientific
reasoning that remain coherent, given the structure of
modern physics and, contrastingly, the types of assertion
that can now be viewed as the residue of a
materialistic bias stemming from superseded physics.
Entirely acceptable are
correlational analyses about the
2 J.M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
relationship between mentalistic data and neurophysiological
mechanisms. Examining the qualitative and
quantitative aspects of brain function, and doing
detailed analyses of how they relate to the data of experience,
obtained through increasingly sophisticated
means of psychological investigation and subject selfreport
analysis (e.g. the entire September–October
2003 issue of
Journal of Consciousness Studies, volume
10, number 9–10, is dedicated to these questions), are
completely in line with fundamental physics. These
activities are the core of neuropsychological science.
What is not justified is the presumption, either tacit or
explicit, that
all aspects of experience examined and
reported are necessarily causal consequences solely of
brain mechanisms. The structure of contemporary
physics entails no such conclusion. This is particularly
relevant to data from first-person reports about active,
wilfully directed attentional focus, and especially to data
pertaining to which aspects of the stream of conscious
awareness a subject chooses to focus on when making
self-directed efforts to modify and/or modulate the
quality and beam of attention. In such cases, the
structure of orthodox quantum physics implies that
the investigator is not justified in assuming that the focus
of attention is determined wholly by brain mechanisms
that are in principle completely well-defined and
mechanically determined. Conscious effort itself can,
justifiably within science, be taken to be a primary
variable whose complete causal origins may be
untraceable
in principle
, but whose causal efficacy in the physical
world can be explained on the basis of the laws of
physics.
As already emphasized, the cognitive frame in which
neuroscience research, including research on cerebral
aspects of behaviour, is generally conducted contains
within it the assumption that brain mechanisms are in
principle fully sufficient to explain all of the observed
phenomena. In the fields of functional neuroimaging,
this has led to experimental paradigms that focus
primarily on changes in brain activation as primary
variables used to explain whatever behavioural changes
are observed—including ones understood as involving
essentially cognitive and emotional responses. As long
as one is investigating phenomena that are mostly
passive in nature this may be fully justified. A person is
shown a picture depicting an emotionally or perhaps a
sexually arousing scene. The relevant limbic and/or
diencephalic structures are activated. The investigator
generally concludes that the observed brain activation
has some intrinsic causal role in the emotional changes
reported (or, perhaps, the hormonal correlates of those
changes).
This method is all well and good, as far as it goes. In
addition, from the experimental subject’s perspective, it
is all quite passive—all that is really required on his or her
part is to remain reasonably awake and alert or, more
precisely, at least somewhat responsive to sensory
inputs. But when, as happens in a growing number of
studies, the subject makes an active response aimed at
systematically
altering the nature of the emotional
reaction—for example, by actively performing a cognitive
reattribution—then the demand that the data be
understood solely from the perspective of brain-based
causal mechanism is a severe and counter-intuitive
constraint. It is noteworthy that this demand for an
entirely brain-based causal mechanism is nullified, in
the quantum model developed here, by a specified
quantum effect, which will be described in detail below.
Surmounting the limitations imposed by restricting
one’s ideas to the failed concepts of classic physics
can be especially important when one is investigating
how to develop improved methods for altering the
emotional and cerebral responses to significantly
stressful external or internally generated stimuli. An
incorrect assignment of the causal roles of neurophysiologically
and mentalistically described variables can
impact negatively on a therapist’s selection of a course
of treatment, on a patient’s capacity to recover, and on
a neuroscientist’s design of clinically relevant research
programmes.
In the analysis and development of clinical practices
involving psychological treatments and their biological
effects, the possession and use of a rationally coherent
and physically allowable conception of the causal
relationship between mind and brain (or, if one prefers,
mentalistic and neurophysiological variables) is critical.
If one simply accepts the standard presumption that all
aspects of emotional response are passively determined
by neurobiological mechanisms, then the theoretical
development of genuinely effective self-directed
psychological strategies that produce real neurobiological
changes can be impeded by the fact that one is
using a theory that excludes from the dynamics what
logically can be, and in our model actually are, key
causal elements, namely our wilful choices.
The clinician’s attention is thus directed away from
what can be in many cases, at the level of actual
practice, a powerful determinant of action, namely the
subject’s psychologically (i.e. mentalistically) framed
commitment to act or think in specific ways. The
therapist tends to becomes locked into the view that the
psychological
treatment of ailments caused by neurobiological
impairments
is not a realistic goal.
There is already a wealth of data arguing against this
view. For instance, work in the 1990s on patients with
obsessive compulsive disorder demonstrated significant
changes in caudate nucleus metabolism and the
functional relationships of the orbitofrontal cortex–
striatum–thalamus circuitry in patients who responded
to a psychological treatment using cognitive reframing
and attentional refocusing as key aspects of the
therapeutic intervention (for review, see
Schwartz &
Begley 2002
). More recently, work by Beauregard and
colleagues (
Paquette et al. 2003) has demonstrated
systematic changes in the dorsolateral prefrontal cortex
and parahippocampal gyrus after cognitive-behavioural
therapy for phobia of spiders, with brain changes significantly
related to both objective measurements and
subjective reports of fear and aversion. There are now
numerous reports on the effects of self-directed
regulation of emotional response, via cognitive reframing
and attentional re-contextualization mechanisms,
on cerebral function (e.g.
Schwartz et al. 1996;
Beauregard
et al. 2001; Ochsner et al. 2002; Le´vesque
et al
. 2003; Paquette et al. 2003;).
The brain area generally activated in all the studies
done so far on the self-directed regulation of emotional
response is the prefrontal cortex, a cortical region also
Model of mind–brain interaction
J. M. Schwartz and others 3
Phil. Trans. R. Soc. B
activated in studies of cerebral correlates of wilful
mental activity, particularly those investigating selfinitiated
action and the act of attending to one’s own
actions (
Spence & Frith 1999; Schwartz & Begley
2002
). There is, however, one aspect of wilful mental
activity that seems particularly critical to emotional
self-regulation, and that seems to be the critical factor
in its effective application—the factor of focused
dispassionate self-observation that, in a rapidly growing
number of clinical psychology studies, has come to be
called ‘mindfulness’ or ‘mindful awareness’ (
Segal et al.
2002
).
The mental act of clear-minded introspection and
observation, variously known as mindfulness, mindful
awareness, bare attention, the impartial spectator, etc.,
is a well-described psychological phenomenon with a
long and distinguished history in the description of
human mental states (
Nyanaponika 2000). The most
systematic and extensive exposition is in the canonical
texts of classic Buddhism preserved in the Pali language,
a dialect of Sanskrit. Because of the critical importance
of this type of close attentiveness in the practice of
Buddhist meditation, some of its most refined descriptions
in English are in texts concerned with meditative
practice (although it is of critical importance to realize
that the mindful mental state does not require any
specific meditative practice to acquire, and is
certainly
not
in any sense a ‘trance-like’ state).
One particularly well-established description, using
the name ‘bare attention’, is as follows:
Bare Attention is the clear and single-minded awareness
of what actually happens
to us and in us at the
successive moments of perception. It is called ‘Bare’
because it attends just to the bare facts of a perception
as presented either through the five physical senses or
through the mind
.without reacting to them.
(
Nyanaponika 1973, p. 30)
Perhaps the essential characteristic of mindful
observation is that you are just watching, observing
all facts, both inner and outer, very calmly, clearly and
closely. To sustain this attentional perspective over
time, especially during stressful events, invariably
requires the conscious application of effort.
A working hypothesis for ongoing investigation in
human neurophysiology, based on a significant body of
preliminary data, is that the mental action of mindful
awareness specifically modulates the activity of the
prefrontal cortex. Because of the well-established role
of this cortical area in the planning and wilful selection
of self-initiated responses (
Spence & Frith 1999;
Schwartz & Begley 2002
), the capacity of mindful
awareness, and by implication all emotional selfregulating
strategies, to specifically modulate activity
in this critical brain region has tremendous implications
for the fields of mental health and related areas.
It might be claimed that the designs and executions
of successful clinical practices (and of informative
neuropsychological experiments) that depend on the
idea of the causal efficacy of conscious effort, and which
fit so well into the quantum conceptualization that
actually explains the causal efficacy of these efforts,
could just as well be carried out within the conceptual
framework in which the causal efficacy of wilful effort is
an illusion, or is something very different from what it
intuitively seems to be. But such a claim is not easy to
defend. Simple models that are consistent with basic
intuition and lead directly to experimentally demonstrable
conclusions are better than philosophically
intricate ones that lead to the same conclusions. Of
course, if it could be argued that the simple model
could not be true because it violates the basic principles
of physics whereas the more intricate one obeys them,
then there might be reasonable grounds for question or
dispute. But in the present case the reverse is true: it is
the simple model that is built on the basic laws of
physics and it is the arcane and philosophically difficult
model, in which our basic human intuition concerning
the efficacy of mental effort is denied as not being what
it seems to be, which contradicts the laws of physics.
The major theoretical issue we address in this article
is the failure of classic models of neurobiological action
to provide a scientifically adequate account for all of the
mechanisms that are operating when human beings use
self-directed strategies for the purpose of modulating
emotional responses and their cerebral correlates.
Specifically, the assumption that all aspects of mental
activity and emotional life are ultimately explicable
solely in terms of micro-local deterministic brain
activity, with no superposed effects of mental effort,
produces a theoretical structure that both fails to meet
practical scientific needs, and also fails to accord with
the causal structure of modern physics.
In the alternative approach the role played by the
mind, when one is observing and modulating one’s own
emotional states, is an intrinsically active and physically
efficacious process in which mental action is affecting
brain activity in a way concordant with the laws of
physics. A culturally relevant way of framing this
change is to say that contemporary physics imbues
the venerable and therapeutically useful term
‘psychodynamic’ with rigorous neurophysical efficacy.
This new theory of the mind–brain connection is
supportive of clinical practice. Belief in the efficacy of
mental effort in emotional self-regulation is needed
to subjectively access the phenomena (e.g. belief in the
efficacy of effort is required to sustain mindfulness
during stressful events). Moreover, a conceptual
framework in which psychologically described efforts
have effects is needed to explain to patients what they
are supposed to do when directing their inner resources
to the challenging task of modifying emotional and
cerebral responses. Clinical success is jeopardized by a
belief on the part of either therapists or patients that
their mental effort is an illusion or a misconception.
It takes effort for people to achieve therapeutic
results. That is because it requires a redirection of the
brain’s resources away from lower level limbic
responses and toward higher level prefrontal functions—
and this does not happen passively. Rather, it
requires, in actual practice, both wilful training and
directed mental effort. It is semantically inconsistent
and clinically counterproductive to insist that these
kinds of brain changes be viewed as being solely an
intra-cerebral ‘the physical brain changing itself ’ type
of action. That is because practical aspects of the
activity of mind essential to the identification, activation,
application and use of directed mental effort are
4 J.M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
not describable solely in terms of material brain
mechanisms. The core phenomena necessary for the
scientific description of self-directed neuroplasticity are
processes that cannot be elaborated solely in terms of
classic models of physics.
Furthermore, as we will see in detail in the following
sections of this article, orthodox concepts of contemporary
physics are ideally suited to a rational and
practically useful understanding of the action of mindful
self-observation on brain function. Classic models of
physics, which view all action in the physical world as
being ultimately the result of the movements of material
particles, are now seriously out of date, and no longer
need be seen as providing the unique, or the best,
scientifically well-grounded paradigm for investigating
the interface between mind/consciousness and brain.
When people practice self-directed activities for the
purpose of systematically altering patterns of cerebral
activation they are attending to their mental and
emotional
experiences, not merely their limbic or
hypothalamic brain mechanisms. And although no
scientifically oriented person denies that those brain
mechanisms play a critical role in generating those
experiences, precisely what the person is training himor
herself to do is to wilfully
change how those brain
mechanisms operate—and to do that requires attending
to mental experience
per se. It is, in fact, the basic
thesis of self-directed neuroplasticity research that the
way in which a person directs their attention
(e.g. mindfully
or unmindfully) will affect both the experiential
state of the person and the state of his/her brain. The
existence of this close connection between mental effort
and brain activity flows naturally out of the dynamic
principles of contemporary physics, but is, within the
framework of classic physics, a difficult problem that
philosophers of the mind have been intensively engaged
with, particularly for the past 50 years. The core
question is whether the solution to this problem lies
wholly in the eventual development of a more sophisticated
philosophy that is closely aligned with the
classic known-to-be-fundamentally-false conception of
nature, or whether the profound twentieth century
development in physics, that assigns a subtle but
essential causal role to human consciousness, can
usefully inform our understanding of the effects
of human consciousness in neuropsychological experiments
that appear to exhibit the causally efficacious
presence of such effects.
To appreciate the major conceptual changes made in
basic physical theory during the twentieth century, one
must know about certain key features of the older
theory.
3. CLASSIC PHYSICS
Classic physics is a theory of nature that originated with
the work of Isaac Newton in the seventeenth century
and was advanced by the contributions of James Clerk
Maxwell and Albert Einstein. Newton based his theory
on the work of Johannes Kepler, who found that the
planets appeared to move in accordance with a simple
mathematical law, and in ways wholly determined by
their spatial relationships to other objects. Those
motions were apparently
independent of our human
observations of them
.
Newton effectively assumed that all physical objects
were made of tiny miniaturized versions of the planets,
which, like the planets, moved in accordance with
simple mathematical laws, independently of whether
we observed them or not. He found that he could then
explain the motions of the planets and also the motions
of large terrestrial objects and systems, such as cannon
balls, falling apples and the tides, by assuming that
every tiny planet-like particle in the solar system
attracted every other one with a force inversely
proportional to the square of the distance between
them.
This force was an
instantaneous action at a distance: it
acted instantaneously, no matter how far the particles
were apart. This feature troubled Newton. He wrote to
a friend ‘That one body should act upon another
through the vacuum, without the mediation of anything
else, by and through which their action and force may
be conveyed from one to another, is to me so great an
absurdity that I believe no man, who has in philosophical
matters a competent faculty of thinking, can ever
fall into it’ (
Newton 1687, p. 634). Although Newton’s
philosophical persuasion on this point is clear, he
nevertheless formulated his universal law of gravity
without specifying how it was mediated.
Albert Einstein, building on the ideas of Maxwell,
discovered a suitable mediating agent, a distortion of
the structure of space–time itself. Einstein’s contributions
made classic physics into what is called a
local
theory
: there is no action at a distance. All influences are
transmitted essentially by contact interactions between
tiny neighbouring mathematically described ‘entities’,
and no influence propagates faster than the speed of
light.
Classic physics is, moreover,
deterministic: the
interactions are such that the state of the physical
world at any time is completely determined by the state
at any earlier time. Consequently, according to classic
theory, the complete history of the physical world
for all
time
is mechanically fixed by contact interactions
between tiny component parts, together with the initial
condition of the primordial universe.
This result means that, according to classic physics,
you are a mechanical automaton
: your every physical
action was predetermined before you were born solely
by mechanical interactions between tiny mindless
entities. Your mental aspects are
causally redundant:
everything you do is completely determined by
mechanical conditions alone, without any mention of
your thoughts, ideas, feelings or intentions. Your
intuitive feeling that your conscious intentions make a
difference in what you do is, according to the principles
of classic physics, a false and misleading illusion.
There are two possible ways within classic physics to
understand this total incapacity of your mental side
(i.e. your stream of conscious thoughts and feelings) to
make any difference in what you do. The first way is to
consider your thoughts, ideas and feelings to be
epiphenomenal by-products of the activity of your
brain. Your mental side is then a causally impotent
sideshow that
is produced, or caused, by your brain, but
that
produces no reciprocal action back upon your brain.
Model of mind–brain interaction
J. M. Schwartz and others 5
Phil. Trans. R. Soc. B
The second way is to contend that each of your
conscious experiences—each of your thoughts, ideas,
or feelings—is the
very same thing as some pattern of
motion of various tiny parts of your brain.
4. PROBLEMS WITH CLASSIC PHYSICS
William James (
1890, p. 138) argued against the first
possibility, epiphenomenal consciousness, by claiming
that ‘
The particulars of the distribution of consciousness, so
far as we know them,
points to its being efficacious.’ He
noted that consciousness seems to be ‘an organ,
superadded to the other organs which maintain the
animal in its struggle for existence; and the presumption
of course is that it helps him in some way in this
struggle, just as they do. But it cannot help him without
being in some way efficacious and influencing the
course of his bodily history.’ James said that the study
described in his book ‘will show us that consciousness is
at all times primarily a
selecting agency.’ It is present
when choices must be made between different possible
courses of action. He further mentioned that ‘It is to
my mind quite inconceivable that consciousness should
have
nothing to do with a business to which it so
faithfully attends’ (1890, p. 136).
If mental processes and consciousness have no effect
upon the physical world, then what keeps a person’s
mentalworld aligned with their physical situation?What
keeps their pleasures in general alignment with actions
that benefit them, and pains in general correspondence
with things that damage them, if felt pleasures and pains
have no effect at all upon their actions?
These liabilities of the notion of epiphenomenal
mind and consciousness lead many thinkers to turn to
the alternative possibility that a person’s mind and
stream of consciousness is
the very same thing as some
activity in their brain: mind and consciousness are
‘emergent properties’ of brains.
A huge philosophical literature has developed
arguing for and against this idea. The primary
argument against this ‘emergent-identity theory’ position,
within a classic physics framework
, is that in classic
physics the full description of nature is in terms of
numbers assigned to tiny space–time regions, and there
appears to be no way to understand or explain how to
get from such a restricted conceptual structure, which
involves such a small part of the world of experience, to
the whole. How and why should that extremely limited
conceptual structure (which arose basically from
idealizing, by miniaturization, certain features of
observed planetary motions) suffice to explain the
totality of experience, with its pains, sorrows, hopes,
colours, smells and moral judgements? Why,
given the
known failure of classic physics at the fundamental level
,
should that richly endowed whole be explainable in
terms of such a narrowly restricted part?
The core ideas of the arguments in favour of an
identity-emergent theory of mind and consciousness
are illustrated by
Roger Sperry’s (1992) example of a
‘wheel’. A wheel obviously does something: it is
causally efficacious; it carries the cart. It is also an
emergent property
: there is no mention of ‘wheelness’ in
the formulation of the laws of physics and ‘wheelness’
did not exist in the early universe; ‘wheelness’
emerges
only under certain special conditions. And the macroscopic
wheel exercises ‘top-down’ control of its tiny
parts. All these properties are perfectly in line with
classic physics, and with the idea that ‘a wheel is,
precisely, a structure constructed out of its tiny atomic
parts’. So why not suppose mind and consciousness to
be, like ‘wheelness’, emergent properties of their
classically conceived tiny physical parts?
The reason that mind and consciousness are not
analogous to ‘wheelness’, within the context of classic
physics, is that the properties that characterize
‘wheelness’ are properties that are
entailed, within the
conceptual framework of classic physics, by properties
specified in classic physics, whereas the properties that
characterize conscious mental processes, namely the
various ways these processes feel, are not
entailed within
the conceptual structure provided by classic physics,
but by the properties specified by classic physics.
That is the huge difference-in-principle that distinguishes
mind and consciousness from things that,
according to classic physics, are constructible out of the
particles that are postulated to exist by classic physics.
Given the state of motion of each of the tiny physical
parts of a wheel, as it is conceived of in classic physics,
the properties that characterize the wheel (e.g. its
roundness, radius, centre point, rate of rotation, etc.)
are specified within the conceptual framework provided
by the principles of classic physics, which specify only
geometric-type properties such as changing locations
and shapes of conglomerations of particles and
numbers assigned to points in space. But given the
state of motion of each tiny part of the brain, as it is
conceived of in classic physics, the properties that
characterize the stream of consciousness (the painfulness
of the pain, the feeling of the anguish, or of the
sorrow, or of the joy) are not specified, within the
conceptual framework provided by the principles of
classic physics. Thus it is possible, within that classic
physics framework, to strip away those feelings without
disturbing the physical descriptions of the motions of
the tiny parts. One can, within the conceptual framework
of classic physics, take away the consciousness
while leaving intact the properties that enter into that
theoretical construct, namely the locations and
motions of the tiny physical parts of the brain and its
physical environment. But one cannot, within the
conceptual framework provided by classic physics,
take away the physical characteristics that define the
‘wheelness’ of a wheel without affecting the locations
and motions of the tiny physical parts of the wheel.
Because one can, within the conceptual framework
provided by classic physics, strip away mind and
consciousness without affecting the physical behaviour,
one cannot rationally claim,
within that framework, that
mind and consciousness are the
causes of the physical
behaviour, or are
causally efficacious in the physical
world. Thus the ‘identity theory’ or ‘emergent property’
strategy fails in its attempt to make mind and
consciousness efficacious, insofar as one remains
strictly within the conceptual framework provided by
classic physics.Moreover, the whole endeavour to base
brain theory on classic physics is undermined by the
fact that classic theory is unable to account for
behavioural properties (such as electrical and thermal
6 J.M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
conductivity, and elasticity, etc.) that depend sensitively
upon the behaviour of the atomic, molecular and
ionic constituents of a system, and brains are certainly
systems of this kind, as will be discussed in detail later.
Although classic physics is unable to account for
observable properties that depend sensitively on the
behaviours of atoms, molecules and ions, the classic
theory is an approximation to a more accurate theory,
called quantum theory, which
is able to account for
these observable macroscopic properties. But if classic
physics is unable to account for the moderately
complex behavioural properties of most other large
systems, then how can it be expected to account for the
exquisitely complex behavioural properties of thinking
brains?
5. THE QUANTUM APPROACH
Early in the twentieth century scientists discovered
empirically that the principles of classic physics could
not be correct. Moreover, those principles were wrong
in ways that no minor tinkering could ever fix. The
basic
principles
of classic physics were thus replaced by new
basic principles
that account uniformly for all the
successes of the older classic theory and for all the
data that are incompatible with the classic principles.
The key philosophical and scientific achievement of
the founders of quantum theory was to forge a
rationally coherent and practicable linkage between
the two kinds of description 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 us to
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 description by causal laws. 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.
In order to achieve this result, the whole
concept of
what science is
was turned inside out. The core idea of
classic physics was to describe the ‘world out there’,
with no reference to ‘our thoughts in here’. But the core
idea of quantum mechanics is to describe both
our
activities as knowledge-seeking and knowledge-acquiring
agents
, and the knowledge that we thereby acquire. Thus,
quantum theory involves, essentially, what is ‘in here’,
not just what is ‘out there’.
This philosophical shift arises from the
explicit
recognition by quantum physicists that science is
about
what we can know. It is fine to have a beautiful
and elegant mathematical theory about a
really existing
physical world out there
that meets various intellectually
satisfying criteria. But the essential demand of
science is
that the theoretical constructs be tied to the experiences
of the human scientists who devise ways of testing
the theory and of the human engineers and technicians
who both participate in these tests and eventually put
the theory to work. Thus, the structure of a proper
physical theory must involve not only the part describing
the behaviour of the not-directly experienced
theoretically postulated entities, expressed in some
appropriate symbolic language, but also a part describing
the human experiences that are pertinent to these
tests and applications, expressed in the language that
we actually use to describe such experiences to
ourselves and to each other. And the theory must
specify the connection between these two differently
described and differently conceived parts of scientific
practice.
Classic physics meets this final requirement in a
trivial way. The relevant experiences of the human
participants are taken to be direct apprehensions of the
gross properties of large objects composed of huge
numbers of their tiny atomic-scale parts. These
apprehensions (of, for example, the perceived location
and motion of a falling apple or the position of a
pointer on ameasuring device) were taken to be
passive:
they had no effect on the behaviours of the systems
being studied. But the physicists who were examining
the behaviours of systems that depend sensitively upon
the behaviours of their tiny atomic-scale components
found themselves forced to introduce a less trivial
theoretical arrangement. In the new scheme the human
agents are no longer passive observers. They are
considered to be
active agents or participants.
The participation of the agent continues to be
important
even when the only features of the physically
described world being observed are large-scale properties of
measuring devices
. The sensitivity of the behaviour of the
devices to the behaviour of some tiny atomic-scale
particles propagates first to the devices and then to
the observers in such a way that the choice made by an
observer about what sort of knowledge to seek can
profoundly affect the knowledge that can ever be
received either by that observer himself or by any other
observer with whom he can communicate. Thus the
choice
made by the observer about how he or she will act
at a macroscopic level has, at the practical level, a
profound effect on the physical systembeing acted upon.
That conclusion is not surprising. How one acts on a
system would, in general, be
expected to affect it. Nor is
it shocking that the effect of the agent’s actions upon
the system being probed is specified by the quantum
mechanical rules. But the essential point not to be
overlooked is that the logical structure of the basic
physical theory has become fundamentally transformed.
The agent’s choice about how to act has
been introduced into the scientific description at a basic
level and in a way that specifies, mathematically, how
his or her choice about how to act affects the physical
system being acted upon.
The structure of quantum mechanics is such that,
although the effect upon the observed system of the
agent’s choice about how to act is mathematically
specified, the manner in which this choice itself is
determined is not specified. This means that, in the
treatment of experimental data, the choices made by
human agents must be treated as freely chosen input
variables, rather than as mechanical consequences of
Model of mind–brain interaction
J. M. Schwartz and others 7
Phil. Trans. R. Soc. B
any known laws of nature. Quantum theory thereby
converts science’s concept of us from that of a
mechanical automaton, whose conscious choices are
mere cogs in a gigantic mechanical machine, to that of
agents whose conscious free choices affect the physically
described world in a way specified by the theory.
The approximation that reduces quantum theory to
classic physics completely eliminates the important
element of conscious free choice. Hence, from a physics
point of view, trying to understand the connection
between mind/consciousness and brain by going to the
classic approximation is absurd: it amounts to trying to
understand something in an approximation that
eliminates the effect we are trying to study.
This original formulation of quantum theory was
created primarily at an institute in Copenhagen
directed by Niels Bohr and is called ‘the Copenhagen
interpretation’. Owing to the strangeness of the properties
of nature entailed by the new mathematics, the
Copenhagen strategy was to refrain from making any
ordinary sort of ontological claims, but instead to take
an essentially pragmatic stance. Thus, the theory was
formulated
basically as a set of practical rules for how
scientists should go about the tasks of acquiring,
manipulating and using knowledge. Claims about
‘what the world out there is really like’ were considered
to lie beyond
science.
This change in perspective is captured by Heisenberg’s
famous statement:
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 1958, p. 100).
A closely connected change is encapsulated in Niels
Bohr’s dictum that ‘in the great drama of existence we
ourselves are both actors and spectators’ (
Bohr 1963,
p. 15;
1958, p. 81). The emphasis here is on ‘actors’: in
classic physics we were mere spectators. The key idea is
more concretely expressed in statements such as:
The freedom of experimentation, presupposed in
classic 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)
Copenhagen quantum theory is about how the
choices made by conscious human agents affect the
knowledge they can and do acquire about the physically
described systems upon which these agents act. In
order to achieve this re-conceptualization of physics the
Copenhagen formulation separates the physical universe
into two parts, which are described in two
different languages. One part is the observing human
agent plus itsmeasuring devices. This extended ‘agent’,
which includes the devices, is described in mental
terms—in terms of our instructions to colleagues about
how to set up the devices and our reports of what we
then ‘see’, or otherwise consciously experience. The
other part of nature is
the system that the agent is acting
upon
. That part is described in physical terms—in
terms of mathematical properties assigned to tiny
space–time regions. Thus, Copenhagen quantum
theory brings ‘doing science’ into science. In particular,
it brings a crucial part of doing science, namely our
choices about how we will probe nature, directly into
the causal structure. It specifies the effects of these
probing actions upon the systems being probed.
This approach works very well in practice. However,
the body and brain of the human agent, and also their
devices, are composed of atomic constituents. Hence a
complete theory ought to be able to describe these
systems in physical terms.
The great mathematician and logician John von
Neumann formulated quantumtheory in a rigorous way
that allows the bodies and brains of the agents, along
with their measuring devices, to be shifted into the
physically described world. This shift is carried out in a
series of steps, each of which moves more of what the
Copenhagen approach took to be the psychologically
described ‘observing system’ into the physically
described ‘observed system’. At each step the crucial
act of choosing or deciding between possible optional
observing actions remains undetermined by the physical
observed system. This act of choosing is always ascribed
to the observing agent. In the end all that is left of this
agent is what von Neumann calls his ‘abstract ego’. It is
described in psychological terms, and is, in practice, the
stream of consciousness of the agent.
At each step the direct effect of the conscious act is
upon the part of the physically described world that is
closest to the psychologically described world. This
means that, in the end, the causal effect of the agent’s
mental action is on their own brain, or some significant
part of their brain.
von Neumann makes the logical structure of
quantum theory very clear by identifying two very
different processes, which he calls process 1 and
process 2 (
von Neumann 1955, p. 418). Process 2 is
the analogue in quantum theory of the process in classic
physics that takes the state of a system at one time to its
state at a later time. This process 2, like its classic
analogue, is
local and deterministic. However, process 2
by itself is not the whole story: it generates a host of
‘physical worlds’, most of which do not agree with our
human experience. For example, if process 2 were,
from the time of the big bang, the
only process in
nature, then the quantum state (centre point) of the
moon would represent a structure smeared out over a
large part of the sky, and each human body–brain
would likewise be represented by a structure smeared
out continuously over a huge region. Process 2
generates a
cloud of possible worlds, instead of the one
world we actually experience.
This huge disparity between properties generated by
the ‘mechanical’ process 2 and the properties we
actually observe is resolved by invoking process 1.
Any physical theory must, in order to be complete,
specify how the elements of the theory are connected to
human experience. In classic physics this connection is
part of a
metaphysical superstructure: it is not part of the
dynamic process. But in quantum theory a linkage of
the mathematically described physical state to human
experiences is contained in the mathematically
8 J.M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
specified dynamic. This connection is not passive. It is
not a mere
witnessing of a physical feature of nature.
Instead,
it injects into the physical state of the system being
acted upon specific properties that depend upon choices made
by the agent
.
Quantum theory is built upon the practical concept
of intentional actions by agents. Each such action is a
preparation
that is expected or intended to produce
an experiential response or feedback. For example, a
scientist might act to place a Geiger counter near a
radioactive source and expect to see the counter either
‘fire’ during a certain time-interval or not ‘fire’ during
that interval. The experienced response, ‘Yes’ or ‘No’, to
the question, ‘Does the counter fire during the specified
interval?’, specifies one bit of information. Quantum
theory is thus an information-based theory built upon
the preparative actions of information-seeking agents.
Probing actions of this kind are not only performed
by scientists. Every healthy and alert infant is continually
engaged in making wilful efforts that produce
experiential feedbacks and he or she soon begins to
form expectations about what sorts of feedbacks are
probable to follow from some particular kind of effort.
Thus, both empirical science and normal human life
are based on paired realities of this action–response
kind, and our physical and psychological theories are
both basically attempting to understand these linked
realities within a rational conceptual framework.
The basic building blocks of quantum theory are,
then, a set of intentional actions by agents and for each
such action an associated collection of possible ‘Yes’
feedbacks, which are the possible responses that the
agent can judge to be in conformity to the criteria
associated with that intentional act. For example, the
agent is assumed to be able to make the judgement
‘Yes’ the Geiger counter clicked, or ‘No’ the Geiger
counter did not click. Science would be difficult to
pursue if scientists could make no such judgements
about what they are experiencing.
All known physical theories involve idealizations of
one kind or another. In quantum theory the main
idealization is not that every object is made up of
miniature planet-like objects. It is rather that there are
agents that perform intentional acts each of which can
result in feedback that may or may not conform to a
certain criterion associated with that act. One piece of
information is introduced into the world in which that
agent lives, according to whether or not the feedback
conforms to that criterion. The answer places the agent
on one or the other of two alternative possible branches
of the course of world history.
These remarks reveal the enormous difference
between classic physics and quantum physics. In
classic physics the elemental ingredients are tiny
invisible bits of matter that are idealized miniaturized
versions of the planets that we see in the heavens and
that move in ways unaffected by our scrutiny, whereas
in quantum physics the elemental ingredients are
intentional preparative actions by agents, the feedbacks
arising from these actions and the effects of these
actions upon the physically described states of the
probed systems.
This radical restructuring of the form of physical
theory grew out of a seminal discovery by Heisenberg.
That discovery was that in order to get a satisfactory
quantum generalization of a classic theory one must
replace various
numbers in the classic theory by
actions
(operators). A key difference between
numbers and actions is that if A and B are two
actions then AB represents the action obtained by
performing the action A upon the action B. If A and
B are two different actions then generally AB is
different from BA: the order in which actions are
performed matters. But for numbers the order does
not matter: AB
ZBA.
The difference between quantum physics and its
classic approximation resides in the fact that in the
quantum case certain differences AB–BA are proportional
to a number measured by Max Planck in
1900, and called Planck’s constant. Setting those
differences to zero gives the classic approximation.
Thus quantum theory is closely connected to classic
physics, but is incompatible with it, because certain
non-zero
quantities must be replaced by zero to obtain
the classic approximation.
The intentional actions of agents are represented
mathematically in Heisenberg’s space of actions.
A description of how it operates follows.
Each intentional action depends, of course, on the
intention of the agent
and upon the state of the system
upon which this action acts. Each of these
two aspects of
nature
is represented within Heisenberg’s space of
actions by an
action. The idea that a ‘state’ should be
represented by an ‘action’ may sound odd, but
Heisenberg’s key idea was to replace what classic
physics took to be a ‘being’ with a ‘doing’. We shall
denote the
action (or operator) that represents the state
being acted upon by the symbol
S.
An intentional act is an action that is intended to
produce a feedback of a certain conceived or imagined
kind. Of course, no intentional act is certain: one’s
intentions may not be fulfilled. Hence the intentional
action merely puts into play a process that will lead
either to a confirmatory feedback ‘Yes’, the intention is
realized, or to the result ‘No’, the ‘Yes’ response did not
occur.
The effect of this intentional mental act is represented
mathematically by an equation that is one of
the key components of quantum theory. This equation
represents, within quantum mathematics, the effect of
process 1 action upon the quantum state
S of the
system being acted upon. The equation is:
S
/S0 ZPSPCðI KPÞSðI KPÞ:
This formula exhibits the important fact that this
process 1 action changes the state
S of the system being
acted upon into a new state
S0, which is a sum of two
parts.
The first part,
PSP, represents in physical terms, the
possibility in which the experiential feedback called
‘Yes’ appears and the second part, (
IKP)S(IKP),
represents the alternative possibility ‘No’, this ‘Yes’
feedback does not appear. Thus, an effect of the
probing action is injected into the mathematical
description of the physical system being acted upon.
The operator
P is important. The action represented
by
P, acting both on the right and on the left of S, is the
Model of mind–brain interaction
J. M. Schwartz and others 9
Phil. Trans. R. Soc. B
action of eliminating from the state
S all parts of S
except the ‘Yes’ part. That particular retained part is
determined by the choice made by the agent. The
symbol
I is the unit operator, which is essentially
multiplication by the number 1, and the action of
(
IKP), acting both on the right and on the left of S is,
analogously, to eliminate from
S all parts of S except
the ‘No’ parts.
Notice that process 1 produces the
sum of the two
alternative possible feedbacks, not just one or the
other. Since the feedback must either be ‘Yes’ or
‘No
ZNot-Yes’, one might think that process 1, which
keeps both the ‘Yes’ and the ‘No’ possibilities, would do
nothing. But that is not correct. This is a key point. It
can be made absolutely clear by noticing that
S can be
written as a sum of four parts, only two of which survive
the process 1 action:
S
ZPSPCðI KPÞSðI KPÞCPSðI KPÞCðI KPÞSP:
This formula is a strict identity. The dedicated reader
can quickly verify it by collecting the contributions of
the four occurring terms
PSP, PS, SP and S, and
verifying that all terms but
S cancel out. This identity
shows that the state
S is a sum of four parts, two of which
are eliminated by process 1
.
But this means that process 1 has a non-trivial
effect
upon the state being acted upon: it eliminates the two
terms that correspond neither to the appearance of a
‘Yes’ feedback nor to the failure of the ‘Yes’ feedback to
appear.
This result is the
first key point: quantum theory has a
specific causal process, process 1, which produces a
non-trivial effect of an
agent’s choice upon the physical
description of the system being examined. (‘Nature’
will eventually choose between ‘Yes’ and ‘No’, but we
focus here on the prior process 1,
the agent’s choice.
Nature’s subsequent choice we shall call process 3.)
(
a) Free choices
The second key point is this: the agent’s choices are
‘free choices’,
in the specific sense specified below.
Orthodox quantum theory is formulated in a
realistic and practical way. It is structured around the
activities of human agents, who are considered able to
freely elect to probe nature in any one of many possible
ways. Bohr emphasized the freedom of the experimenters
in passages such as the one already quoted
earlier, or the similar:
The foundation of the description of the experimental
conditions as well as our freedom to choose them is
fully retained.
(
Bohr 1958, p. 90)
This freedom of choice stems from the fact that in
the original Copenhagen formulation of quantum
theory the human experimenter is considered to
stand outside the system to which the quantum laws
are applied. Those quantum laws are the only precise
laws of nature recognized by that theory. Thus,
according to the Copenhagen philosophy,
there are no
presently known laws that govern the choices
made by the
agent/experimenter/observer about how the observed
system is to be probed. This choice is thus,
in this very
specific sense
, a ‘free choice’. The von Neumann
generalization leaves this freedom intact. The choices
attributed to von Neumann’s ‘abstract ego’ are nomore
limited by the known rules of quantum theory than are
the choices made by Bohr’s experimenter.
(
b) Nerve terminals, ion channels and the need
to use quantum theory in the study of the
mind–brain connection
Neuroscientists studying the connection of mind
and consciousness to physical processes in the brain
often assume that a conception of nature based on
classic physics will eventually turn out to be adequate.
That assumption would have been reasonable during
the nineteenth century. But now, in the twenty-first
century, it is rationally untenable. Quantum theory
must be used in principle because the behaviour of the
brain depends sensitively upon atomic, molecular and
ionic processes, and these processes in the brain often
involve large quantum effects.
To study quantum effects in brains within an
orthodox (i.e. Copenhagen or von Neumann) quantum
theory one must use the von Neumann formulation.
This is because
Copenhagen quantum theory is
formulated in a way that leaves out the quantum
dynamics of the human observer’s body and brain. But
von Neumann quantum theory takes the physical
system
S upon which the crucial process 1 acts to be
precisely the brain of the agent, or some part of it. Thus
process 1 describes here an interaction between a
person’s stream of consciousness, described in mentalistic
terms, and an activity in their brain, described in
physical terms.
A key question is the
quantitative magnitude of
quantum effects in the brain. They must be large in
order for deviations from classic physics to play any
significant role. To examine this quantitative question
we consider the quantum dynamics of nerve terminals.
Nerve terminals are essential connecting links
between nerve cells. The general way they work is
reasonably well understood. When an action potential
travelling along a nerve fibre reaches a nerve terminal, a
host of ion channels open. Calcium ions enter through
these channels into the interior of the terminal. These
ions migrate from the channel exits to release sites on
vesicles containing neurotransmitter molecules. A
triggering effect of the calcium ions causes these
contents to be dumped into the synaptic cleft that
separates this terminal from a neighbouring neuron,
and these neurotransmitter molecules influence the
tendencies of that neighbouring neuron to ‘fire’.
At their narrowest points, calcium ion channels are
less than a nanometre in diameter (
Cataldi et al. 2002).
This extreme smallness of the opening in the calcium
ion channels has profound quantum mechanical
implications. The narrowness of the channel restricts
the lateral
spatial dimension. Consequently, the lateral
velocity
is forced by the quantum uncertainty principle to
become large. This causes the
quantum cloud of
possibilities
associated with the calcium ion to fan out
over an increasing area as it moves away from the tiny
channel to the target region where the ion will be
absorbed as a whole, or not absorbed at all, on some
small triggering site.
10 J. M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
This spreading of this
ion wave packet means that the
ion may or may not be absorbed on the small triggering
site. Accordingly, the contents of the vesicle may or
may not be released. Consequently, the quantum state
of the brain has a part in which the neurotransmitter is
released and a part in which the neurotransmitter is not
released. This quantum splitting occurs at every one of
the trillions of nerve terminals. This means that the
quantum state of the brain splits into a vast host of
classically conceived possibilities, one for each possible
combination of the release-or-no-release options at
each of the nerve terminals. In fact, because of
uncertainties on timings and locations, what is generated
by the physical processes in the brain will be not a
single discrete set of non-overlapping physical possibilities
but rather a huge
smear of classically conceived
possibilities. Once the physical state of the brain has
evolved into this huge smear of possibilities one must
appeal to the quantum rules, and in particular to the
effects of process 1, in order to connect the physically
described world to the streams of consciousness of the
observer/participants.
This focus on the motions of calcium ions in nerve
terminals is not meant to suggest that this particular
effect is the
only place where quantum effects enter into
the brain process, or that the quantum process 1 acts
locally at these sites. What is needed here is only the
existence of
some large quantum of effect. The focus
upon these calcium ions stems from the facts that (i) in
this case the various sizes (dimensions) needed to
estimate the
magnitude of the quantum effects are
empirically known, and (ii) that the release of
neurotransmitter into synaptic clefts is known to play
a significant role in brain dynamics.
The brain matter is warm and wet and is continually
interacting intensely with its environment. It might be
thought that the strong
quantum decoherence effects
associated with these conditions would wash out all
quantum effects, beyond localized chemical processes
that can be conceived to be imbedded in an essentially
classic world.
Strong decoherence effects are certainly present, but
they are automatically taken into account in the von
Neumann formulation employed here. These effects
merely convert the state
S of the brain into what is
called a ‘statistical mixture’ of ‘nearly classically
describable’ states, each of which develops in time (in
the absence of process 1 events), in an almost classically
describable way.
The existence of strong decoherence effects makes
the main consequences of quantum theory being
discussed here more easily accessible to neuroscientists
by effectively reducing the complex quantum state of
the brain to a collection of almost classically describable
possibilities. Because of the uncertainties introduced
at the ionic, atomic, molecular and electronic
levels, the brain state will develop not into one single
classically describable macroscopic state, as it does in
classic physics, but into a continuous distribution of
parallel virtual states of this kind. Process 1 must then
be invoked to allow definite empirical predictions to be
extracted from this continuous smear of parallel
overlapping almost-classic possibilities generated by
process 2.
(
c) Quantum brain dynamics
A principal function of the brain is to receive clues
from the environment, to form an appropriate plan of
action and to direct and monitor the activities of the
brain and body specified by the selected plan of action.
The exact details of the plan will, for a classic model,
obviously depend upon the exact values of many noisy
and uncontrolled variables. In cases close to a
bifurcation point, the dynamic effects of noise might
even tip the balance between two very different
responses to the given clues, for example, tip the
balance between the ‘fight’ or ‘flight’ response to some
shadowy form. It is important to realize that the exact
values accounting for what in classic physics models are
called ‘dynamic effects of noise’ are unknowable in
principle. The contemporary physical model accounts
for these uncertainties in brain dynamics.
The effect of the independent ‘release’ or ‘do not
release’ options at each of the trigger sites, coupled with
the uncertainty in the timing of the vesicle release at
each of the trillions of nerve terminals, will be to cause
the quantum mechanical state of the brain to become
a smeared-out cloud of different macroscopic possibilities,
some representing different alternative possible
plans of action. As long as the brain dynamic is
controlled wholly by process 2—which is the quantum
generalization of the Newtonian laws of motion of
classic physics—all of the various alternative possible
plans of action will exist in parallel, with no one plan of
action singled out as the one that will actually be
experienced.
Some process beyond the local deterministic process
2 is required to pick out one experienced course of
physical events from the smeared-out mass of possibilities
generated by all of the alternative possible
combinations of vesicle releases at all of the trillions
of nerve terminals. As already emphasized, this other
process is process 1. This process brings in a
choice that
is not determined by any currently known law of
nature, yet has a definite effect upon the brain of the
chooser. The process 1 choice picks an operator
P and
also a time
t at which P acts. The effect of this action at
time
t is to change the state S(t) of the brain, or of some
large part of the brain, to
PS
ðtÞP CðI KPÞSðtÞðI KPÞ:
The action
P cannot act at a point in the brain, because
action at a point would dump a huge (in principle
infinite) amount of energy into the brain, which would
then explode. The operator
P must, therefore, act nonlocally,
over a potentially large part of the brain.
In examining the question of the nature of the effect
in the brain of process 2 we focused on the separate
motions of the individual particles. But the physical
structures in terms of which the action of process 1 is
naturally expressed are not the separate motions of
individual particles. They are, rather, the
quasi-stable
macroscopic degrees of freedom
. The brain structures
selected by the action of
P must enjoy the stability,
endurance and causal linkages needed to bring the
intended experiential feedbacks into being.
These functional structures are probably more like
the lowest-energy state of the simple harmonic
Model of mind–brain interaction
J. M. Schwartz and others 11
Phil. Trans. R. Soc. B
oscillator, which is completely stable, or like the states
obtained from such lowest-energy states by spatial
displacements and shifts in velocity. These shifted
states tend to
endure as oscillating states. In other words,
in order to create the needed causal structure the
projection operator
P corresponding to an intentional
action ought to pick out functionally pertinent quasistable
oscillating states of macroscopic subsystems of the
brain
. The state associated with a process 1 preparatory
intervention should be a functionally important brain
analogue of a collection of oscillating modes of a
drumhead, in which large assemblies of particles are
moving in a coordinated way. Such an enduring
structure in the brain can serve as a trigger and
coordinator of further coordinated activities.
(
d) Templates for action
The brain process that is actualized by the transition
S
(t)/PS(t)P is the neural correlate of the psychologically
intended action. It is the brain’s template for the
intended action. It is a pattern of neuroelectrical
activity that, if held in place long enough, will tend to
generate a physical action in the brain that will tend to
produce the intended experiential feedback.
(
e) Origin of the choices of the process 1 actions
It has been repeatedly emphasized here that the
choices by which process 1 actions actually occur are
‘free choices’ in the sense that they are not specified by
the currently known laws of physics. On the other hand,
a person’s intentions are surely related in some way to
their historical past. This means that the laws of
contemporary orthodox quantum theory, although
restrictive and important, do not provide a complete
picture. In spite of this, orthodox quantum theory,
while making no claim to ontological completeness, is
able to achieve a certain kind of
pragmatic completeness.
It does so by treating the process 1 ‘free choices’ as the
input variables of experimental protocols, rather than
mechanically determined consequences of brain
action.
In quantum physics
the ‘free choices’ made by human
subjects are regarded as subjectively controllable input
variables
. Bohr emphasized that ‘the mathematical
structure of the quantum mechanical formalism offers
the appropriate latitude’ for these free choices. But the
need for this strategic move goes deeper than the mere
fact that contemporary quantum theory fails to specify
how these choices are made. For if in the von Neumann
formulation one does seek to determine the cause of the
‘free choice’ within the representation of the physical
brain of the chooser, one finds that one is
systematically
blocked from determining the cause of the choice by
the Heisenberg uncertainty principle, which asserts
that the locations and velocities of, say, the calcium
ions, are simultaneously unknowable to the precision
needed to determine what the choice will be. Thus, one
is not only faced with merely a practical unknowability
of the causal origin of the ‘free choices’, but with an
unknowability in principle
that stems from the uncertainty
principle itself, which lies at the base of quantum
mechanics. There is thus a deep root in quantum
theory for the idea that the origin of the ‘free choices’
does not lie in the physical description alone and also
for the consequent policy of treating these ‘free choices’
as empirical inputs that are selected by agents and enter
into the causal structure via process 1.
(
f) Effort
It is useful to classify process 1 events as either
‘active’ or ‘passive’.
Passive process 1 events are
attentional events that occur with little or no feeling
of conscious effort.
Active process 1 events are
intentional and involve effort. This distinction is given
a functional significance by allowing ‘effort’ to enter
into the selection of process 1 events in a way that will
now be specified.
Consciousness probably contributes very little to
brain dynamics compared with the contribution of the
brain itself. To minimize the input of consciousness,
and in order to achieve testability, we propose to allow
mental effort to do nothing but control ‘attention
density’, which is the rapidity of the process 1 events.
This allows effort to have only a very limited kind of
influence on brain activities, which are largely controlled
by physical properties of the brain itself.
The notion that only the attention density is
controlled by conscious effort arose from an investigation
into what sort of conscious control over process
1 action was sufficient to accommodate the most
blatant empirical facts. Imposing this strong restriction
on the allowed effects of consciousness produces a
theory with correspondingly strong predictive power.
In this model all significant effects of consciousness
upon brain activity arise exclusively from a well-known
and well-verified strictly quantum effect known as the
‘quantum Zeno effect’ (QZE).
(
g) The quantum Zeno effect
If one considers only passive events, then it is very
difficult to identify any empirical effect of process 1,
apart from the occurrence of awareness. In the first
place, the empirical averaging over the ‘Yes’ and ‘No’
possibilities in strict accordance with the quantum laws
tends to wash out all effects that depart from what
would arise from a classic statistical analysis that
incorporates the uncertainty principle as simply lack
of knowledge. Moreover, the passivity of the mental
process means that we have no empirically controllable
variable.
However, the study of effortfully controlled intentional
action brings in two empirically accessible
variables, the intention and the amount of effort. It
also brings in the important physical QZE. This effect is
named for the Greek philosopher Zeno of Elea, and
was brought into prominence in 1977 by the physicists
Misra & Sudarshan (1977)
. It gives a name to the fact
that repeated and closely spaced observational acts can
effectively hold the ‘Yes’ feedback in place for an
extended time-interval that depends upon the
rapidity
at which the process 1 actions are happening
. According to
our model, this rapidity is controlled by the amount of
effort being applied. In our notation, the effect is to
keep the ‘Yes’ condition associated with states of the
form
PSP in place longer than would be the case if no
effort were being made. This ‘holding’ effect can
override very strong mechanical forces arising from
process 2.
12 J. M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
The ‘Yes’ states
PSP are assumed to be conditioned
by training and learning to contain the template for
action which if held in place for an extended period will
tend to produce the intended experiential feedback.
Thus, the model allows intentional mental efforts to
tend to bring intended experiences into being. Systems
that have the capacity to exploit this feature of natural
law, as it is represented in quantum theory, would
apparently enjoy a tremendous survival advantage over
systems that do not or cannot exploit it.
6. SUPPORT FROM PSYCHOLOGY
A person’s experiential life is a stream of conscious
experiences. The person’s experienced ‘
self’ is part of
this stream of consciousness: it is not an extra thing that
lies outside what the person is conscious of. In James’s
words (
1890, p. 401) ‘thought is itself the thinker, and
psychology need not look beyond’. The experiential
‘self ’ is a slowly changing ‘fringe’ part of the stream of
consciousness. This part of the streamof consciousness
provides an overall background cause for the central
focus of attention.
The physical brain, evolving mechanically in accordance
with the local deterministic process 2, can domost
of the necessary work of the brain. It can do the job of
creating, on the basis of its interpretation of the clues
provided by the senses, a suitable response, which will
be controlled by a certain pattern of neural or brain
activity that acts as a
template for action. However, owing
to its quantum character, the brain necessarily generates
an amorphous mass of overlapping and conflicting
templates for action. Process 1 acts to extract from
this jumbled mass of possibilities some particular
template for action. This template is a feature of the
‘Yes’ states
PSP that specifies the form of the process 1
event. But the quantum rules do not assert that this
‘Yes’ part of the prior state
S necessarily comes into
being. They assert, instead, that if this process 1 action
is triggered (for example, by some sort of ‘consent’)
then this ‘Yes’ component
PSP will come into being
with probability Tr
PSP/Tr S, and that the ‘No’ state
will occur if the ‘Yes’ state does not occur, where the
symbol Tr represents a quantum mechanical summation
over all possibilities.
If the rate at which these ‘consents’ occur is assumed
to be
increasable by conscious mental effort, then the
causal efficacy of ‘will’ can be understood. Conscious
effort can, by activation of the QZE, override strong
mechanical forces arising from process 2 and
cause the
template for action to be held in place longer than it
would be if the rapid sequence of process 1 events were
not occurring. This sustained existence of the template
for action can increase the probability that the intended
action will occur.
Does this quantum-physics-based concept of the
origin of the causal efficacy of ‘will’ accord with the
findings of psychology?
Consider some passages from
Psychology: the briefer
course
, written by William James. In the final section of
the chapter on attention, James (
1892, p. 227) 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 the 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.
In the chapter on will, in the section entitled
‘Volitional effort is effort of attention’, James (
1892,
p. 417) 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 will on the course
of mental–cerebral processes is remarkably in line
with
what had been proposed independently from purely
theoretical considerations of the quantum physics of this
process
. The connections specified by James are
explained
on the basis of the same dynamic principles
that had been introduced by physicists to explain
atomic phenomena. Thus the whole range of science,
from atomic physics to mind–brain dynamics, has the
possibility of being brought together into a single
rationally coherent theory of an evolving cosmos that
is constituted not of
matter but of actions by agents. In
this conceptualization of nature, agents could naturally
evolve in accordance with the principles of
natural selection, owing to the fact that their efforts
have physical consequences. The outline of a possible
rationally coherent understanding of the connection
between mind and matter begins to emerge.
In the quantum theory of mind/consciousness–brain
being described here, there are altogether three processes.
First, there is the purely mechanical process
called process 2. As discussed at length in the book,
Mind, matter, and quantum mechanics
(Stapp 1993/2003,
p. 150), this process, as it applies to the brain, involves
important dynamic units that are represented by
complex patterns of brain activity that are ‘facilitated’
(i.e. strengthened) by use and are 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—that is, by
activation of several of its parts—coupled to feedback
loops that strengthen or weaken the activities of
Model of mind–brain interaction
J. M. Schwartz and others 13
Phil. Trans. R. Soc. B
appropriate processing centres, appears to account for
the essential features of the mechanical part of the
dynamics in a way that is not significantly different from
what a classic model can support, except for the
existence of a host of parallel possibilities that according
to the classic concepts, cannot exist simultaneously.
The second process, von Neumann’s process 1, is
needed in order to pick out from a chaotic continuum
of overlapping parallel possibilities some particular
discrete possibility and its complement. (The complement
can be further divided, but the essential action
is present in the choice of one particular ‘Yes’ state
PS
(t)P from the morass of possibilities in which it is
imbedded.) The third process is nature’s choice
between ‘Yes’ and ‘No’. Nature’s choice conforms to
a statistical rule, but the agent’s choice is, within
contemporary quantum theory, a ‘free choice’ that can
be and is consistently treated as an input variable of the
empirical protocol.
Process 1 has itself two modes. The first is passive,
and can produce temporally isolated events. The
second is active and involves mental effort.
Active
process 1 intervention has, according to the
quantum model described here, a distinctive form. It
consists of a sequence of intentional purposeful
actions, the rapidity of which can be increased with
effort. Such an increase in attention density, defined as
an increase in the number of observations per unit
time, can bring into play the QZE, which tends to hold
in place both those aspects of the state of the brain
that are fixed by the sequence of intentional actions
and also the felt intentional focus of these actions.
Attention density is not controlled by any physical rule
of orthodox contemporary quantum theory, but is
taken both in orthodox theory and in our model, to be
subject to subjective volitional control. This application
in this way of the basic principles of physics to
neuroscience constitutes our model of the mind–brain
connection.
(
a) Support from psychology of attention
A huge amount of empirical work on attention has
been done since the nineteenth century writings of
William James. Much of it is summarized and analysed
in
Harold Pashler’s (1998) book The psychology of
attention
. Pashler organizes his discussion by separating
perceptual processing from post-perceptual processing.
The former type covers processing that, first of all,
identifies such basic physical properties of stimuli as
location, colour, loudness and pitch and, secondly,
identifies stimuli in terms of categories ofmeaning. The
post-perceptual process covers the tasks of producing
motor actions and cognitive action beyond mere
categorical identification. Pashler emphasizes that the
empirical ‘findings of attention studies
.argue for a
distinction between perceptual attentional limitations
and more central limitations involved in thought and
the planning of action’ (p. 33). The existence of these
two different processes with different characteristics is a
principal theme of Pashler’s book (e.g. pp. 33, 263,
293, 317, 404).
A striking difference that emerges from the analysis
of the many sophisticated experiments is that the
perceptual processes proceed essentially in parallel,
whereas the post-perceptual processes of planning and
executing actions form a single queue. This is in line
with the distinction between ‘passive’ and ‘active’
processes. The former are essentially a passive stream
of essentially isolated process 1 events, whereas the
‘active’ processes involve effort-induced rapid
sequences of process 1 events that can saturate a
given capacity. This idea of a limited capacity for serial
processing of effort-based inputs is the main conclusion
of Pashler’s book. It is in accord with the quantumbased
model, supplemented by the condition that there
is a limit to how many effortful process 1 events per
second a person can produce during a particular stage
of their development.
Examination of Pashler’s book shows that this
quantum model accommodates naturally all of the
complex structural features of the empirical data that
he describes. Of key importance is his chapter 6, in
which he emphasizes 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
describes.
Pashler describes four empirical signatures for this
kind of bottleneck and describes the experimental
confirmation of each of them (p. 279). 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.
The queuing effect is illustrated in a nineteenth
century result described by Pashler: mental exertion
reduces the amount of physical force that a person can
apply. He notes that ‘This puzzling phenomenon
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 Schro¨dinger equation (process 2). This opposing
tendency is produced by the QZE 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.
The important point here is that there is in principle,
in the quantum model, an essential dynamic difference
between the unconscious processing done by the
Schro¨dinger evolution, which generates by a local
process an expanding collection of classically conceivable
experiential possibilities and the process associated
with the sequence of conscious events that
constitute the wilful selection of action. The former
are not limited by the queuing effect, because process 2
simply develops all of the possibilities in parallel. Nor is
the stream of essentially isolated passive process 1 events
thus limited. It is the closely packed active process 1
events that can, in the von Neumann formulation, be
limited by the queuing effect.
The very numerous experiments cited by Pashler all
seem to be in line with the quantum approach. It is
important to note that this bottleneck is not automatic
within classic physics. A classic model could easily
produce, simultaneously, two responses in different
14 J. M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
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 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
(p. 308). This could be accounted for by the necessarily
non-local character of the projection operator
P.
An interesting experiment mentioned by Pashler
involves the simultaneous tasks of doing an IQ test and
giving a foot response to a rapidly presented sequence
of tones of either 2000 or 250 Hz. The subject’s mental
age, asmeasured 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 to both
‘intelligent’ behaviour, which requires complex effortful
processing, and the simple wilful selection of a
motor response.
Pashler also notes 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’ (p. 348).
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’ (p. 383). 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, through quantum selection
and reduction, bits of control information that reflect
mental evaluation. Pashler notes ‘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’ (p. 385). All of these
empirical connections are in line with the general
principle that effort increases attention density, with
an attendant increase in the rate of directed conscious
events, each of which inputs a mental evaluation and a
selection or focusing of a course of action.
Additional supporting evidence comes from the
studies of the stabilization or storage of information
in short-term memory (STM). According to the
physics-based theory, the passive aspect of conscious
process merely actualizes an event that occurs in
accordance with some brain-controlled rule and this
rule-selected process then develops automatically, with
perhaps some occasional monitoring. Thus, the theory
would predict that the process of stabilization or
storage in STM of a certain sequence of stimuli should
be able to 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, STM is stored in patterns of brain
activity, whereas consciously directed actions are
associated with the active selection of a sub-ensemble
of quasi-classic states. This distinction seems to
account for the large amount of detailed data that
bear on this question of the relationship of the
stabilization or storage of information in STM to the
types of task that require wilfully directed actions (pp.
337–341). In marked contrast to STM function,
storage or retrieval of information from long-term
memory (LTM) is a task that requires actions of just
this sort (pp. 347–350).
Deliberate storage in, or retrieval from, LTM
requires wilfully directed action 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
wilful conscious selection should not be interfered with
by 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 and
whatever processing may feed back to change the
allocation of perceptual attention itself ’ (p. 353).
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 classic neurophysiological
approach, to the questions of what makes these
two mechanisms so different, and what the connection
between them is (pp. 354–356, 386–387).
After considering various possible mechanisms that
could cause the central bottleneck, Pashler concludes
that ‘the question of why this should be the case is quite
puzzling’ (pp. 307–308). Thus, the fact that this
bottleneck and its basic properties seem to follow
automatically from the same laws that explain the
complex empirical evidence in the fields of classic and
quantum physics means that the theory being presented
here has significant explanatory power for the
experimental data of cognitive psychology. Further, it
coherently explains aspects of the data that have
heretofore not been adequately addressed by currently
applicable theoretical perspectives.
These features of the phenomena may be claimed by
some to be potentially explainable within a classicalphysics-
based model. But the possibility of such an
explanation is profoundly undermined by the absence
from classic physics of the notion of conscious choice
and effort. These consciousness-connected features, so
critical to a coherent explanation of the psychology of
human attention, however, already exist and are
specified features of the causal structure of fundamental
contemporary physical theory.
7. APPLICATION TO NEUROPSYCHOLOGY
The quantum model is better suited to the analysis of
neuropsychological data than models based on the
classic approximation. For, just as in the treatment of
atomic systems, the quantum approach brings the
phenomenologically described data
directly into the
dynamics in place of microscopic variables that are, in
Model of mind–brain interaction
J. M. Schwartz and others 15
Phil. Trans. R. Soc. B
principle, unknowable. Quantum theory injects
directly into the causal structure the phenomenal
descriptions that we human beings use in order to
communicate to our colleagues the empirical facts. It
thereby specifies a useful and testable causal structure,
while evading the restrictive classic demand that the
causal process be ‘bottom up’, i.e. expressible in terms
of local mechanical interactions between tiny mindless
entities. The Heisenberg uncertainty principle renders
that ideal
unachievable in principle and the banishment
of that microlocal ‘bottom up’ determinism opens the
door to the quantum alternative of injecting the
phenomenologically described realities directly into
the causal structure in the way that is both allowed and
described by contemporary physical theory.
Quantum physics works better in neuropsychology
than its classic approximation precisely because it
inserts knowable choices made by human agents into
the dynamics in place of unknowable-in-principle
microscopic variables. To illustrate this point we
apply the quantum approach to the experiment of
Ochsner
et al. (2002).
Reduced to its essence, this experiment consists first
of a training phase in which the subject is taught how to
distinguish, and respond differently to, two instructions
given while viewing emotionally disturbing visual
images: ‘attend’ (meaning passively ‘be aware of, but
not try to alter, any feelings elicited by’) or ‘reappraise’
(meaning actively ‘reinterpret the content so that it no
longer elicits a negative response’). Second, the
subjects perform these mental actions during brain
data acquisition. The visual stimuli, when passively
attended to, activate limbic brain areas, and when
actively reappraised, activate prefrontal cerebral
regions.
From the classic materialist point of view this is
essentially a conditioning experiment where, however,
the ‘conditioning’ is achieved through linguistic access
to cognitive faculties. But how do the cognitive realities
involving ‘knowing’, ‘understanding’ and ‘feeling’ arise
out of motions of the miniature planet-like objects of
classic physics, which have no trace of any experiential
quality? How do the vibrations in the air that carry the
instructions get converted into feelings of understanding?
And how do these feelings of understanding get
converted to conscious effort, the presence or absence
of which determine whether the limbic or frontal
regions of the brain will be activated?
Within the framework of classic physics these
connections between feelings and brain activities
remain huge mysteries. The materialist claim (Karl
Popper called this historicist prophecy ‘
promissory
materialism
’) is that someday these connections will be
understood. But the question is whether these connections
should reasonably be expected to be understood
in terms of a physical theory that is known to be false,
and to be false in ways that are absolutely and
fundamentally germane to the issue. The classic
concept demands that the choices made by human
agents about how they will act be determined by
microscopic variables that according to quantum
theory are indeterminate in principle. The reductionist
demand that the course of human experience be
determined by local mechanical processes is the very
thing that is most conclusively ruled out by the
structure of natural phenomena specified by contemporary
physical theory. To expect the mind–brain
connection to be understood within a framework of
ideas so contrary to the principles of physics is
scientifically unsupportable and unreasonable.
There are important similarities and also important
differences between the classic and quantum explanations
of the experiments of
Ochsner et al. (2002). In
both approaches the atomic constituents of the brain
can be conceived to be collected into nerves and other
biological structures and into fluxes of ions and
electrons, which can all be described reasonably well
in essentially classic terms. In the classic approach the
dynamics must in principle be describable in terms of
the local deterministic classic laws that, according to
those principles, are supposed to govern the motions of
the atomic-sized entities.
The quantum approach is fundamentally different.
In the first place the idea that all causation is
fundamentally mechanical
is dropped as being prejudicial
and unsupported either by direct evidence or by
contemporary physical theory. The quantum model of
the human person is essentially dualistic, with one of the
two components being described in psychological
language and the other being described in physical
terms. The empirical/phenomenal evidence coming
from subjective reports is treated as data pertaining to
the psychologically described component of the person,
whereas the data from objective observations, or from
measurements made
upon that person, are treated as
conditions on the physically described component of the
person. The apparent causal connection
manifested in the
experiments
between these two components of the agent
is then explained by the causal connections between
these components
that are specified by the quantum laws.
The quantum laws, insofar as they pertain to
empirical data, are organized around
events that
increase the amount of information lodged in the
psychologically described component of the theoretical
structure. The
effects of these psychologically identified
events upon the physical state of the associated brain
are specified by process 1 (followed by ‘Nature’s
statistical choice’ of which the discrete options specified
by process 1 will be experienced). When no effort is
applied, the temporal development of the body/brain
will be approximately in accord with the principles of
classic
statistical mechanics, for reasons described
earlier in connection with the strong
decoherence effects.
But important departures from the classic statistical
predictions can be caused by conscious effort. This
effort can cause to be held in place for an extended
period, a pattern of neural activity that constitutes a
template for action
. This delay can tend to cause the
specified action to occur. In the experiments of
Ochsner the effort of the subject to ‘reappraise’
causes
the ‘reappraise’ template to be held in place and the
holding in place of this template
causes the suppression
of the limbic response. These causal effects are, by the
QZE, mathematical consequences of the quantum
rules. Thus the ‘subjective’ and ‘objective’ aspects of
the data are tied together by quantum rules that
directly
specify the causal effects upon the subject’s brain of the
choices made by the subject, without needing to specify how
16 J. M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
these choices came about
. The form of the quantum laws
accommodates a natural dynamic breakpoint between
the
cause of wilful action, which is not specified by the
theory, and its
effects, which are specified by the theory.
Quantum theory was designed to deal with cases in
which the conscious action of an agent—to perform
some particular probing action—enters into the
dynamics in an essential way. Within the context of
the experiment by
Ochsner et al. (2002), quantum
theory provides, via the process 1 mechanism, an
explicit means whereby the successful effort to ‘rethink
feelings’ actually causes—by catching and actively
holding in place—the prefrontal activations critical to
the experimentally observed deactivation of the
amygdala and orbitofrontal cortex. The resulting
intention-induced modulation
of limbic mechanisms
that putatively generate the frightening aversive feelings
associated with passively attending to the target stimuli
is the key factor necessary for the achievement of the
emotional self-regulation seen in the active cognitive
reappraisal condition. Thus, within the quantum
framework, the causal relationship between the mental
work of mindfully reappraising and the observed brain
changes presumed to be necessary for emotional selfregulation
is
dynamically accounted for. Furthermore,
and crucially, it is accounted for in ways that fully allow
for communicating to others the means used by living
human experimental subjects to attain the desired
outcome. The classic materialist approach to these
data, as detailed earlier in this article, by no means
allows for such effective communication. Analogous
quantum mechanical reasoning can of course be used
mutatis mutandis
to explain the data of Beauregard et al.
(2001) and related studies of self-directed neuroplasticity
(see
Schwartz & Begley 2002).
8. CONCLUSIONS
Materialist ontology draws no support from contemporary
physics and is in fact contradicted by it. The
notion that all physical behaviour is explainable in
principle solely in terms of a local mechanical process is
a holdover from physical theories of an earlier era. It
was rejected by the founders of quantum mechanics,
who introduced, crucially into the basic dynamical
equations, choices that are not determined by local
mechanical processes, but are rather attributed to
human agents. These orthodox quantum equations,
applied to human brains in the way suggested by John
von Neumann, provide for a causal account of recent
neuropsychological data. In this account brain behaviour
that appears to be caused by mental effort is
actually caused by mental effort: the causal efficacy of
mental effort is no illusion. Our wilful choices enter
neither as redundant nor epiphenomenal effects, but
rather as fundamental dynamical elements that have
the causal efficacy that the objective data appear to
assign to them.
A shift to this pragmatic approach that incorporates
agent-based choices as primary empirical input variables
may be as important to progress in neuroscience
and psychology as it was to progress in atomic physics.
The work of the second-named author (H.P.S.) was
supported in part by the Director, Office of Science, Office
of High Energy and Nuclear Physics, Division of High Energy
Physics, of the US Department of Energy under Contract
DE-AC03-76SF00098. The work of the third-named author
(M.B.) was supported in part by a scholarship from the Fonds
de la Recherche en Sante´ du Que´bec (FRSQ). We thank
Joseph O’Neill for his insightful comments about preliminary
versions of our manuscript.
APPENDIX A. OTHER INTERPRETATIONS
This work is based on the Copenhagen Interpretation
of quantum theory, and von Neumann’s extension of it.
The Copenhagen Interpretation is what is, in essence,
both taught in standard quantum physics courses and
used in actual practice. This interpretation brings the
human agent into the dynamics at a crucial point,
namely to resolve the ‘basis’ problem, i.e. to pose some
particular physical question. This entry of the agent’s
‘free’ choice is the basis of the present work.
Many of the physicists who are most acutely
interested in the logical and physical foundations of
quantum theory reject the Copenhagen Interpretation,
which is basically epistemological and have sought to
invent alternative formulations that can be regarded as
descriptions of what is really going on in nature. The
three most-discussed alternatives are the ones associated
with the names of Roger Penrose, Hugh Everett
and David Bohm. In order to provide a broader
conceptual foundation for understanding and assessing
the Copenhagen–von Neumann approach used here we
shall compare it with those other three.
All three of the alternative approaches accept von
Neumann’s move of treating the entire physical world
quantum mechanically. In particular, the bodies and
brains of the agents are treated as conglomerations of
such things as quantum mechanically described electrons,
ions and photons.
Penrose (1994)
accepts the need for consciousrelated
process 1 events, and wants to explain
when they
occur. He proposes an explanation that is tied to
another quantum mystery, that of quantum gravity.
Suppose the quantum state of a brain develops two
components corresponding to the ‘Yes’ and ‘No’
answers to some query. Penrose proposes a rule,
based on the gravitational interaction between these
two parts, that specifies approximately how long before
a collapse will occur to one branch or to the other. In
this way the question of
when the answer ‘Yes’ or ‘No’
occurs is given a ‘physical’ explanation.
Penrose and his
collaborator Hameroff (1996)
calculate estimates of
this typical time-interval on the basis of some detailed
assumptions about the brain. The result is a time of the
order of one-tenth of a second. They argue that the
rough agreement of this number with time-intervals
normally associated with consciousness lends strong
support to their theory.
The Penrose–Hameroff model requires that the
quantum state of the brain has a property called
macroscopic quantum coherence
, which needs to be
maintained for around a tenth of a second. But,
according to calculations made by
Max Tegmark
(2000)
, this property ought not to hold for more than
about 10
K13 s. Hameroff and co-workers (Hagen et al.
2002
) have advanced reasons why this number should
actually be of the order of a tenth of a second. But 12
Model of mind–brain interaction
J. M. Schwartz and others 17
Phil. Trans. R. Soc. B
orders of magnitude is a very big difference to explain
away and serious doubts remain about whether the
Penrose–Hameroff theory is technically viable.
If
all aspects of the collapse process were similarly
determined in an essentially mechanical way, then
there would be in quantum mechanics, as in classic
physics, nothing for consciousness to do. But
Penrose
(1994)
argues that the effects of consciousness cannot
be purely algorithmic: it cannot be governed by a finite
set of rules and operations. His argument is based
on the famous incompleteness theorem of Go¨ del.
However, the logical validity of his argument has been
vigorously challenged by many experts, including
Hillary
Putnam (1994), and Penrose’s conclusion
cannot be deemed absolutely secure. Also, it is peculiar
that the question of
when the event occurs should
be essentially algorithmic, while the process itself is
non-algorithmic.
However, Penrose’s overall aims are similar to those
of the approach made in this paper, namely to
recognize that the process-1-related features of quantum
mechanics are dynamically very different from the
local mechanistic dynamics of classic mechanics, or of
its quantum analogue, process 2. This differing
character of process 1, which is closely connected
to conscious awareness, seems, on its face, to be
signalling the entry of an essentially non-mechanical
consciousness-related element into brain dynamics.
Everett (1957)
proposed another way to deal with
the problem of how the quantum formulae are tied to
our conscious experiences. It is called the many-worlds
or many-minds approach. The basic idea is that nature
makes no choices between the ‘Yes’ and ‘No’ possibilities:
both options actually do occur. But, owing to
certain features of quantum mechanics, the two
streams of consciousness in which these two alternative
answers appear are dynamically independent: neither
one has any effect on the other. Hence the two
incompatible streams exist in parallel
epistemological
worlds, although in the one single ontological or
physical quantum world.
This many-minds approach is plausible within the
framework provided by quantum mathematics. It
evades the need for any real choices between the ‘Yes’
and ‘No’ answers to the question posed by the process
1 action. However, von Neumann never even mentions
any real choice between ‘Yes’ and ‘No’ and the
founders of quantum theory likewise focus attention
on the crucial
choice of which question shall be posed. It is
this
choice, which is in the hands of the agent, that the
present paper has focused upon. The subsequent
choice between ‘Yes’ and ‘No’, is normally deemed
to be made by nature. But it is enough that the latter
choice merely
seems to be made in accordance with the
quantum probably rules. The real problem with the
many-minds approach is that its proponents have not
yet adequately explained how one can evade the
process 1 choices. This difficulty is discussed in detail
in
Stapp (2002).
David Bohm’s pilot-wave model (
Bohm 1952)
seems at first to be another way of evading the problem
of how to tie the formulae of quantum mechanics to
human experiences. Yet in David Bohm’s book with
Basil Hiley (
Bohm & Hiley 1993) the last two chapters
go far beyond the reasonably well-defined pilot-wave
model and attempt to deal with the problem dealt with
in the works of
Stapp (1990) and of Gell-Mann &
Hartle (1989)
. This leads Bohm into a discussion of his
concept of the implicate order, which is far less
mathematically well-defined than his pilot-wavemodel.
Bohm saw a need to deal with consciousness and
wrote a detailed paper on it (
Bohm 1986, 1990). His
proposals go far beyond the simple well-defined pilotwave
model. It involves an infinite tower of pilot waves,
each controlling the level below. The engaging simplicity
of the original pilot-wave model is lost in this
infinite tower.
The sum of all this is that the structure of quantum
theory indicates the need for a non-mechanistic
consciousness-related process, but that the approaches
to quantum theory that go beyond the pragmatic
Copenhagen–von Neumann approach have serious
problems that have yet to be resolved. We, in this
paper, have chosen to stay on the safer ground of
orthodox pragmatic quantum theory and to explore
what can be said within that framework.
However, in this addendum we will now stray very
briefly from our strict adherence to the pragmatic
stance, in order to get a glimpse into what seems to us
to be the pathway beyond contemporary pragmatic
science that is pointed to by the structure of contemporary
physics.
The core message of quantum theory appears to be
that the basic realities are ‘knowables’ not ‘be-ables’:
they are things that can be known, not realities that exist
yet cannot be known. This conclusion can be strongly
defended by a detailed analysis of quantum theory, but
this is not place to do so. However, given this premise,
the programme of passing from the anthropocentric set
of pragmatic rules to a conception of the greater reality
in which our streams of human consciousness are
imbedded takes on a different complexion. If nature is
constructed of knowables, then the acts of knowing with
which we are familiar should be special cases of a
pervasive set of similar acts: the world should somehow
be constructed of such acts, and of a substrate that is
suited to be acted upon by such acts, but that supports,
as a matter of principle, only what can become known by
other acts. Acts of knowing become, then, the primitives
of nature, along with the substrate upon which they act.
Conscious acts of probing must also be encompassed.
This way of understanding the meaning of quantum
theory opens the door, in principle, to the formulation
of rules that allow the choices of which probing actions
are taken to depend not exclusively on the current
condition of the physically/mathematically described
substrate—that is, the current state of the brain—but
also on prior acts of knowing. Thus it could well be, as
James’s remarks suggest, that a mechanical rule
determines which thought is
initially caught, but that
felt properties of the consequent act of knowing can
influence the rapidity of follow-up repetitions of the
probing action.
It is not our intention to propose in this appendix
some testable proposal along these lines. We merely
note that quantum theory seems naturally to point to
this route for an understanding of the reality that lies
behind our human-knowledge-based science.
18 J. M. Schwartz and others
Model of mind–brain interaction
Phil. Trans. R. Soc. B
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