INEVITABLITY OF BRAIN
LATERALITY- BASED BEHAVIORAL DIFFERENCES
FROM THE VARIABLE SIDEDNESS OF THE BRAIN
EXECUTIVE SYSTEM
Bruce Eldine Morton,
ABSTRACT:
Quantitative measurement
of brain laterality-based behaviors has enabled reconstitution of
“hemisphericity” within a new binary context.
That is, about half of males and females appear to be born with their
unilateral executive located in the functionally asymmetric left hemisphere,
biasing them as more top-down, deductive “splitters”. The other half with their executives on the
right tend to be more bottom-up, inductive “lumpers”. A three
minute MRI brain scan provided a primary standard for hemisphericity, based upon
the larger side of the ventral anterior cingulate cortex. This permitted assessment of earlier
methods. Forced-choice binary statements
answered by calibrated hemisphericity subjects led to the identification of
twenty seven behavioral right or left brain preferences. Further, it was observed that higher
education and career choice resulted in hemisphericity sorting of an
undifferentiated population entering college.
In addition it was found that certain sex and hemisphericity traits are
being conflated by society. This was
supported by the finding that right brain oriented persons of either sex had
larger corpus callosi than left brainers,
and that individuals of the same hemisphericity had more personality traits in
common, than those of the same sex but different hemisphericity. In conclusion, behavioral laterality appears
to be a valid and promising area for quantitative neuroscience research.
TEXT:
INEVITABLITY OF BRAIN
LATERALITY- BASED BEHAVIORAL DIFFERENCES
FROM THE VARIABLE SIDEDNESS OF THE BRAIN
EXECUTIVE SYSTEM
This review is written out of the necessity to reverse the powerful effect of public criticism in the literature upon the possible existence of brain behavioral laterality. That attack resulted in the termination of funding and research on hemisphericity in particular, and upon behavioral laterality in general. As a result, it has become almost impossible to get reviewers seriously to consider research reports for publication in this area. In spite of this, recently unfunded neuroscience research developments, some published by this author, appear to make the existence of brain laterality based behavior inevitable. These research observations require the reconstitution of some form of hemisphericity, here in a modified binary context. This review seeks to justify a neuroscience-based quantitative return to this interesting and important area of brain research.
1. The Reconstitution of Hemisphericity into a
Binary Format
1.2. Two
Novel Contexts Providing Useful Insights about Behavioral Laterality
Two unorthodox
contexts have provided unexpected insights about behavioral laterality. First, it has long seemed logically
compelling that, by definition there can be but one executive element in any
functioning behavioral system or institution.
Within the constraints of the bilateral vertebrate brain, this demands
that the site of executive system function must be unilateral, Descartes’
central pineal “seat of the soul” not withstanding [1]. Thus, the first unorthodox insight was that
the executive system of the human brain is unilateral. Support for this new idea will follow.
Second, if the anterior cingulate
cortex (ACC) is the most probable site for the executive system [2-6] including
its impressive preconscious decision-making skills [7,8],
then both the anatomical [9-13] and functional asymmetry [14-16] often reported
for this bilateral structure are not unexpected. Therefore, the second unorthodox insight was
that the structure responsible for the functional operation of the human
unilateral executive system is individually located inherently on one side of
the asymmetric anterior cingulate cortex or the other.
Experimental support for the existence of single-sided executive function
was provided by hemisometer studies to be described later in which the site of
the brain “observer” was found to be unilateral for 95% of 91 subjects
[17]. Crucially, in these studies, the
side of the observer was also highly correlated with the side of subject
hemisphericity. These new ideas have
been further reinforced by MRI observations on 150 subjects, also to be
presented later. These indicated that
the larger side of the ventral gyrus of the ACC (putative site of the executive
system) and the side of subject hemisphericity are both located on the same
side of the brain [18].
This review is
based upon the unexpectedly rich, but parsimonious consequences that emerge
from application of the above two experimentally supported premises to
investigations of human behavioral differences:
1. A unilateral executive system exists, 2. within
the larger side of the anterior cingulate cortex, inherently located either in
the right or left hemisphere.
1.2. Development of
Quantitative Methods for the Determination of Behavioral Laterality
From these two new
perspectives, it appears unavoidable that the possession of a unilateral
executive would impart an inherent cognitive and behavioral bias upon any
individual, depending within which of the functionally asymmetric right or left
hemispheres their executive was embedded.
Recognition of such a behavioral bias, along with its implicit question,
“Which side am I on?”, appear to be the underlying origin of the earlier
proposed concept of “hemisphericity” with its contrasting right brain vs. left
brain thinking and behavioral styles [19].
However, due to lack of understanding of the binary (rather than
gradient) nature of these behavioral differences and lack of quantitative
methods, the provocative claims of hemisphericity could not be confirmed and
research on the topic was brought to a halt as “a concept ahead of its time”
[20].
Recently, four polymodal, highly intercorrelated
biophysical measures have been developed which provided the first quantitative
measures of the right or left brain cognitive and behavioral styles, both for
individuals and groups [21-23]. These
developments, together with the above new theoretical paradigm, have provided
new approaches to reassess the existence and nature of the cognitive and
behavioral manifestations of some form of “hemisphericity”.
The first of these
physiological measures was based upon the inability of the minor ear in about
half of 150 subjects to report consonant-vowel syllables during dichotic
listening [24]. This subgroup of
so-called “dichotically deaf” individuals was later found to be enriched in
putative left brain-oriented persons. In
contrast, the other subgroup containing those reporting quite well with their
minor ears was found to be enriched in right brain-oriented persons [25].
Next, a second
biophysical hemisphericity measure was developed that employed the timed
mirror-tracing of the outline of a five pointed star, each hand competing with
the other [21]. About half of the 150
right-handed subjects were faster with their left hand than their right
hand. This seemingly contra-intuitive
result was interpreted as supporting a right brain location of the
predominating hemisphere with these individuals, based upon the observation
that forelimbs are almost exclusively directed by the opposite side of the
brain [26]. As
predicted, these right-handed subjects with faster left hands were later found
to be right brain-oriented persons. Left
brain oriented persons (also right handed) were faster with their right
hand. Most importantly, the individuals
within two groups separated by this mirror tracing method were significantly
correlated with those in the two groups separated by the dichotic listening
technique.
The third biophysical
measure of hemisphericity was based upon a two-handed line- bisection test
derived from [27]. Here again about half
of 109 right-handed subjects were more accurate in bisecting 40 horizontal
lines (7-16 cm in length) with their left hand than with their right hand
[22]. This group was also later found to
be highly enriched in right brain-oriented persons. This would be predicted, assuming the more
predominant side of the brain made more accurate line bisection estimates. In contrast, the group found to make more
accurate line bisections with their right hands was enriched in left brain
oriented persons. Again, the two groups
separated by the “Best Hand Test” were highly correlated with those separated by
the Dichotic Deafness Test as well as those separated by the Mirror Tracing
Test.
Development of the
fourth and last biophysical measure of hemisphericity required the invention of
the above-mentioned Hemisometer (Figure 1).
Using this device, a single source, 0.5 ms flash was simultaneously
emitted from two small orifices, one on the left and the other on the right
side of the viewing field. These were
directed only to the subject’s nasal, or their temporal retinae
by the incorporation of appropriate baffles within two prototype instruments
(see upper section of Figure 1). Of 91
subjects, 95% reported the flash consistently appeared first on one side only,
or on the other. The side of the
hemisometer from which the 0.5 ms flash was reported by the individual to have
appeared first, was presumed to be the brain side of the executive. This is because the flash going to the
non-executive side would be delayed by at least 10 ms (from 2 to18 ms) [28-30], while it detoured across
the corpus callosum to the true side of the executive, thus appearing second as
a result of this delay. Again,
remarkably, the two groups separated by the Hemisometer were found to be
composed mostly of the same individuals separated by the three other
biophysical methods [23]. Correlations
between these four polymodal methods averaged r =
0.61, p=0.000 [18].
1.3. Discovery of Neuroanatomical Markers of Behavioral Laterality
Most importantly,
the right or left brain orientation of individuals, assessed by the above four
biophysical methods, was essentially congruent with the larger side of the
ventral gyrus of the anterior cingulate cortex (Figure 2), as revealed by a 3
minute MRI procedure [18]. As a
strategically, the MRI detectable laterality of this anatomically-defined putative
executive
Figure 1:
Flash Hemisometer Design and Function, Subject with left Executive
Legend:
For both hemisometers, if the executive system
must be reached by crossing the corpus callosum, the increased neural path
length will add about 10 msec to the overall time
elapsed. Therefore, if executive is on
the left, then the flash from the right for either hemisometer will arrive
about 10 msec before the one from the left. Vise
versa if executive is on right.
structure was then assigned
as the primary standard defining individual behavioral hemisphericity, a term
to be more fully defined later. As a
result, the hemisphericity of any individual could readily and accurately be
determined.
Figure 2. Anterior Cingulate Asymmetries: The Four Hemisphericity Types
Legend: MRI sagittal
images of subjects were taken 6mm right and left of the midline of calibrated
hemisphericity subjects. A: R-bom (right brain-oriented male), B: R-bof
(right brain-oriented female), C: L-bom (left brain-oriented male), and D: L-bof (right
brain-oriented female). Arrows reaching
from the lower surface of the corpus callosum to the cingulate sulcus (CS)
above illustrate the four measurements made for each subject. The paracingulate sulcus (PCS), if present,
is seen above the CS. If the arrows were
longest on the left hemisphere, subjects were placed into the left
brain-oriented bin, and visa versa [18].
For the first time, the stage was set to
ask and answer specific, concrete questions about the basis and nature of
individual behavioral laterality.
1.4. Reassessment of
Earlier Objections to the Concept of Hemisphericity.
Before proceeding
to new investigations of the interesting behavioral manifestations of this new
binary construct of hemisphericity, it is necessary to address the issues
brought up in a critical review of hemisphericity by Beaumont, Young, and
McManus in 1984 [20] that signaled the death knell to hemisphericity as an
accepted research topic within the Neurosciences. Its abstract follows: “Hemisphericity refers to the idea that people
may rely on a preferred mode of cognitive processing, which is linked to
activity on the part of the left or right cerebral hemispheres. Four methods have been used in hemisphericity
research: lateral eye- movements, electro-physiological measures, questionnaires
and cognitive tests. It is demonstrated
that none has been properly validated with respect to the purposes for which
they are employed in studies on hemisphericity.
It is argued that the idea of hemisphericity lacks adequate foundation
and that, because of the assumptions implicit in the idea of hemisphericity, it
will never be possible to provide such a foundation. The idea is misleading and
should be abandoned.”
In the introduction
of their “Critical Review of Hemisphericty, Beaumont
et al., [20], indicated concern that hemisphericity had become linked to many
areas of social
significance, including
personality, reasoning, thought, abnormal states, education, development,
college performance, creativity and problem solving, poetry, mysticism, prayer,
and consciousness without sound scientific evidence. Although they accepted the existence of
cerebral hemisphere laterality, they correctly took issue with an idea of
hemisphericity in which “it generally indicated the idea that each individual
may tend to rely on a preferred mode of cognitive processing which in turn
implies the predominant activity of either the left or the right cerebral
hemisphere.” Their questions were: How clear was the link between “hemisphericity”
and brain laterality? Was it valid, or
just neuromythology or neurophrenology? In their review, they proposed to examine the empirical
and theoretical bases of hemisphericity research.
As they noted, the
first appearance of the term “hemisphericity” occurred in 1972 [19]. This idea had evolved from the writings of
Joseph Bogen, a neurosurgeon participating in the
now-famous split-brain studies of the 1960s [26, 31,32]. As is the case today [33], the catastrophic
symptoms of certain intractable epileptics were found to be markedly
ameliorated by preventing the crossing of a seizure from its site of origin to
the other side of the brain. This was
first accomplished by separating their upper brain by a surgical procedure
called a commissurotomy, which severed at midline the
structures of the corpus callosum, the anterior, and
sometimes posterior commissures [34, 35]. By neurologically testing these split brain
patients, Bogen and others compiled unavoidable
evidence that the so called “redundant, minor, or non language” right hemisphere
was an actually a fully active participant in what appeared to be unique and
important neurological processes, including some associated with nonverbal
creativity [36-38]. This new discovery
was demonstrated to the public by ingenious experiments [31, 32] vividly
demonstrating that the right side of the brain was a full, if less articulate
participant in the panoply of human consciousness.
Born from the
excitement of these revelations, an obvious possibility immediately presented
itself, that individuals may differ in the relative expression of the
properties of their two different hemispheres, an idea that remains unavoidable
today. Indeed, in the presence of
functionally asymmetric hemispheres, the existence of some form of individual
difference in behavioral laterality could be said to be inevitable. Yet, early attempts to
formalize and marshal evidence supporting this simple idea [19] were fraught
with misconceptualizations, errors, and dead-ends. Such misassumptions, including Bogen’s own concept of hemisphericity, failed to include
even a proper definition of what appears to be the true underlying
phenomenon. It was upon these early
false starts regarding the possible existence of individual differences in
behavioral laterality and, if they existed, to understand their origin and
nature that
The review authors
noted that the main lines of investigation of hemisphericity had primarily
relied upon four different assessments: 1) Tachistoscopic
investigations of lateral eye-movements seeking asymmetric responses based upon
verbal-nonverbal stimuli differences, 2) Electrophysiological measures using
EEG and evoked potentials to probe for unilateral activations under different
stimuli, 3) Questionnaires: most of
which were based upon attempts to measure relative preferences for putative
right hemisphere creativity, 4) Cognitive tests, most of which depended upon an
assumed verbal-nonverbal distinction for laterality. All of these approaches were judged not to
measure hemisphericity [20], a conclusion with which the present author
concurs. Yet, the reviewers stated that,
“It is not inconceivable that simple cognitive performance measures might be
devised which could serve as a measure of hemisphericity, but one has yet to be
developed to which a reasonable degree of validity can be attributed.” As outlined in the forgoing, this has now been
multiply accomplished, resulting in the identification of a neuroantomical
absolute standard (the above laterality of ventral gyrus of the ACC) for
hemisphericity.
Next, the reviewers
of hemisphericity decried that no external validation studies of hemisphericity
existed. Most convincing to them would
have been the use of hemisphericity to correctly identify the laterality of
cerebral lesions. Although such evidence
remains absent, the combination of this idea with the new concept of a
unilateral executive suggests some interesting possibilities. For example, would an individual with their
executive on the left react differently to a left side stroke than one whose executive
was on their right, (or vice versa for certain right side strokes), for
example, in terms of the now seemingly idiosyncratic manifestations of alien
limb and other syndromes?
However, when the
visual field and dichotic listening methods, hesitantly accepted by the
reviewers as alternatives to the independent assessment of hemisphericity, were
tried on groups of professionals such as doctors, lawyers, and sculptors and
showed no relationships, they were lead to conclude: “This undermines any belief in validity of
hemisphericity as currently assessed.”
However, as will be demonstrated later [39] each of these professional
fields is composed of mixed hemisphericity groups, almost equal in size. Therefore, it appears the authors may have
been carrying some uninspected assumptions about the
expected predominant composition of individuals within these professions.
Another potential
validation that caught the attention of the reviewers was that of dyslexic
subjects, who had been reported to show a right dominant profile by Gordon [40]
on his Cognitive Laterality Battery.
But, as neither dyslexics nor controls differed in dichotic listening as
authors expected they should, they concluded differences in lateralization were
not required to explain the differences of dyslexia. However, although dyslexics indeed appear to
be normally lateralized in certain regards, recently Morton (unpublished)
measured the hemisphericity of more than one hundred mildly dyslexic, formerly
reading-delayed adult subjects. Not one
was left brain-oriented. As we shall see
later, dyslexia appears to originate from quite an unexpected source. Other reports of independent confirmations of
hemisphericity were mentioned by the authors, but they felt these were too few
to be meaningful [20].
Since the empirical
studies reviewed by the authors were judged to be inadequately grounded in
fact, the question arose: Was this due to the poor quality of the work, or to
an unsound idea? This brought them to an
assessment of the theoretical basis of the concept of hemisphericity. Objections to the idea of hemisphericity
itself were then made on three theoretical grounds. The first was due to a confusion of
terminology. There was a noted failure
to define or agree upon the meaning of terms used. As defined in their review, “Hemisphericity
refers to the idea that an individual may tend to rely on a preferred mode of
cognitive processing which is linked to predominant activity on the part of
either the left or the right cerebral hemisphere” [20]. Questions raised included the following. Was this lateral activity “preferred” or
“predominant”? Was it a voluntary
strategy, or was it involuntary? When
one hemisphere predominated, did the other shut down completely or remain
active at some reduced level? Why can’t
both be active at same time? Previous
answers given had ranged from: the side activated varies from task to task, to the answer that one hemisphere is preferentially
activated regardless of the task.
With the reconstitution
of hemisphericity into a binary format (this review), a new context for the
origin and nature of cognitive and behavioral laterality that appears more
functionally “fit” than the former one, many of these questions seem obsolete. Now, hemisphericity becomes a description
based possible individual cognitive and behavioral differences based upon the
existence of a unilateral executive inherently embedded in one or the other
side of the cerebrum. This view of
hemisphericity imposes an unavoidable local behavioral bias on the individual,
depending within which of the asymmetric hemispheres his or her executive is
located. This bias is based upon 1) time
delays to intercommunicate across the callosum with the opposite hemisphere, 2)
upon non-symmetrical callosal interconnections
between hemispheres, 3) upon non-symmetrical inhibitions between the sides, and
4) upon greater accessibility to local asymmetric cognitive resources than to
those available from the opposite hemisphere [23].
As will be seen
below, no modulation of lateral activity is involved in hemisphericity,
personally intended or otherwise. From
its inherent asymmetric location, the unilateral executive simply serves
logistically to coordinate optimal survival of the organism. The characteristic right and left brain
cognitive and behavioral orientations of hemisphericity, to be described later,
are the result of local bias upon its operation, imposed by the asymmetry of
whichever hemisphere within which it was located.
The
reviewers’ second objection about the theoretical basis of “hemisphericity” was
based upon the use of certain dichotomies.
They felt that, thus far, the hemisphericity specialization dichotomies
used had not been grounded in fact for two reasons: 1) Because of use of too free an
extrapolation from split brain studies and 2) because of the small experimental
differences found between normal subjects.
Furthermore, inappropriate deduction of new
dichotomies were felt to have arisen from an association with earlier
ones. i.e., the right hemisphere is
intuitive because it is analogical because it is non verbal, etc. They concluded that, “to be of lasting value,
the idea of hemisphericity will have to contribute something that is not
already present in the existing literature on individual differences; it must
do more than simply map onto distinctions such as verbal vs. non verbal that
have already been explored in some detail.
This is unlikely to happen if the method of arriving at dichotomies
outlined above continues to be employed”.
As will be seen in
the next section, this has now abundantly been accomplished. For example, based upon the development of
biophysical standards leading to a neuroanatomical
absolute hemisphericity standard, four new preference questionnaires have been
devised which were not based upon brain laterality considerations at all. As will be described later, these have
uncovered 27 binary differences as diverse as: 1) morning or evening
functioning, 2) the need to recover from upset alone or in the presence of an
important another, 3) the taking or avoidance of blame, 3) conservatism or
boldness, etc.
The authors further
decry that “hemisphericity research is predicated on the view that suitable
dichotomies can be found between individuals, because of three implicit
assumptions, which may be questioned”:
1) Hemispheric differences are qualitative. 2) Certain cerebral asymmetries may not
reflect larger global hemispheric asymmetries. 3) Hemispheric differences exist
because of fundamental incompatibilities between different psychological
processes, which need to be physically separated [20]. Within the new paradigm of hemisphericity,
the existence of a unilateral executive system in one or the other sides of the
asymmetric hemispheres is logically sufficient to account for all behavioral
and cognitive differences noted. The
veracity of the above three assumptions is no longer required to empirically
demonstrate the presence of these individual differences or to explain their
dichotic nature or basis of control.
The third objection
that the reviewers had with the theoretical basis of hemisphericity was based
upon issues of cerebral control [20].
They state that a problem that many found with hemisphericity is that it
seemed to ignore that both hemispheres work together in normal people to form a
single integrated system. From the
binary context of hemisphericity, where indeed each unilateral executive must
integrate and best use its bilateral resources within the asymmetrical
limitations imposed upon it, this is no longer an issue.
They also felt that
in hemisphericity the problem of “metacontrol” had
not been addressed. How was the control
of physically separate, qualitative different, incompatible processes
achieved? For example they felt that
hemisphericity ascribed to the corpus callosum the status of being a nerve
fiber tract that is capable of forming a coordinating link between incompatible
processes in a way in which intra-hemispheric fiber tracts are implicitly
incapable. They said that no reason had
been offered as to why incompatible processes (if such exist) could not be kept
separate within the same hemisphere without any deficit [20]. It has since become clear that many
functional modules do exist whose laterality are individually sorted
genetically or in development, including handedness, pen grasp posture,
language side, etc. From the binary
paradigm of hemisphericity, however, there are no longer issues of control
because no attempt is made to control the relative activities of any
element. Although there can be two
asymmetric hemispheres, by definition there can only be one executive
system. These asymmetric elements on
both sides each become accessible to the executive system within the bias of
its unilateral locus, and appear to be used to their fullest as appropriate to
the task at hand based upon their relative accessibility.
Finally, regarding
the current status of hemisphericity, the review authors found hemisphericity
to be based upon invalid tests and invalid inferences drawn upon an unsound
concept. Moreover, the way some of the
hemisphericity research had been used made it cause for general concern. As ideas derived from hemisphericity had no
scientific basis, they felt these should not have been used to form the basis
of attempts to influence educational and social policy.
Lastly, they ask
themselves if the hemisphericity research were more rigorous, might it provide
useful findings? They felt the signs
were not encouraging. Tests are
difficult to design and administer. Poor
correlations between different measures of cerebral laterality were found. The possibility for quick easy testing
appeared discouraging. Left and right
hemisphere dichotomies were unsubstantiated, and probably wrong in
principle. Thus, they conclude that,
“On the basis of the present review, it would seem prudent to abandon the
notion of hemisphericity, at least in so far as it claims to make any reference
to the lateral function of the cerebral hemispheres. Such a claim cannot be supported by current
scientific studies of cognitive function of cerebral hemispheres, and it is
most unlikely that more thorough understanding of the relation between
cognitive function and verbal structural systems will lead to any change in
this state of affairs.” [20].
In terms of the
earlier failed model of hemisphericity, the present author completely agrees
with these conclusions. Fortunately for
the progress of science, paradigm shifts periodically do occur. Like the fearsome cataracts at the edge of
the world which suddenly evaporate when the earth is viewed as round, so from
the new binary context of hemisphericity, virtually all of the above problems
with the hemisphericity model simply disappear as irrelevant to the existence
of individual behavioral laterality. No
doubt, a new set of problems arise, but these await objective analysis by
future critics. Hopefully, as with most
successive approximations, this new model will be a more accurate
representation of external reality of brain and behavior that the previous one
was. It certainly has provided an
abundance of socially significant new insights, as we shall see.
Then, what do we
have at this point? Hemisphericity refers to measurable individual right or left-brain
dyadic cognitive and behavioral orientation differences that are the
consequence of the existence of a unilateral executive system inherently
imbedded either in the right or left asymmetric cerebral hemispheres.
1.5. Behavioral
Differences between Right and Left Brain-Oriented Persons.
A set of simple
abbreviations were developed as a form of hemisphericity
nomenclature to facilitate convenient labeling of the various
hemisphericity types. Thus, right or
left brain-oriented persons, were
designated as R-bops or L-bops, while right or left brain-oriented males
were called R-boms or L-boms. Right or left brain oriented females
were called R-bofs or L-bofs. These abbreviations are used throughout the
remainder of this review.
With the advent of
the four biophysical and one neuroanatomical
quantitative measures of hemisphericity it became possible to ask the many MRI
calibrated hemisphericity subjects to complete sets of specifically designed
questions in order to explore differences in the cognitive and behavioral
orientations of right and left brain-oriented groups (n = 110). To this end, these studies utilized one old
and unpublished questionnaire by Zenhauser [41],
reported to have 70% agreement with the once popular “Styles of Learning and
Thinking Questionnaire of
To summarize these
studies (Table 1), 28 behavioral dyads emerged, each being significant
(p<0.05). These were organized under
five areas: logic orientation, consciousness type, sensitivity level, social
orientation, and spousal dominance.
One of the earlier
hemisphericity model misconceptions, avoided in the new round of preference
questionnaires, was the idea that individuals are located somewhere on a
gradient of laterality between left and right extremes. In contrast, implicit in the new binary new
hemisphericity model is the concept of the lateral location of one’s executive
system by which one is born either a R-bop or
L-bop. Thus, while one may hone their transcallosal skills for accessing the opposite side of
their brain by experience and education, the executive system cannot be
transplanted to the other side. Therefore,
the new questionnaires employed, “Either-Or”, forced choice dichotic statements
in which the subject was required to select the statement alternative that was
not necessarily identical, but the one that was judged to be the closest to
their own viewpoint, however interpreted.
This eliminated a substantial loss of power occurring in earlier
questionnaires where subjects indicated that their view was to some degree
intermediate between the dichotomies listed.
Table 1: Twenty-eight Binary Behavioral Correlates of
Hemisphericity
Left Brain-Oriented Persons Right
Brain-Oriented Persons
LOGICAL ORIENTATION
Analytical
(stays within the limits of the data)
See the big picture (projects
beyond data, predicts)
Uses logic
to convert objects to literal concepts Imagines,
converts concepts to contexts or metaphors Decisions based on objective facts Decisions
based on feelings
Uses a
serious approach to solving problems Use
a playful approach to solving problems
Prefers to
maintain and use good old solutions Would rather find better new solutions.
TYPE OF
CONSCIOUSNESS
Daydreams
are not vivid Has vivid daydreams
Doesn’t
often remember dreams Remember
dreams often.
Thinking
often consists of words Thinking
often consists of mental pictures or images
Comfortable
and productive with chaos Slowed
by disorder and disorganization
Can easily
concentrate on many things at once Tends
to concentrate on one thing in depth at a time
Often
thinking tends to ignore surroundings Observant
and in touch with surroundings
FEAR LEVEL AND
SENSITIVITY
Sensitive
in relating to others Intense
in relating to others
Tend to
avoid talking about emotional feelings Often
talks about own and others feelings of emotion
Suppresses
emotions as overwhelming Seeks to experience and express
emotions more deeply
Would
self-medicate with depressants Would self-medicate with stimulants
SOCIAL AND
PROFESSIONAL ORIENTATION
Independent,
hidden, private, and indirect Interdependent,
open, public, and direct
Avoids
seeking evaluation by others Seeks
frank feedback from others
Usually
tries to avoid taking the blame Tends to take the blame, blames self, or apologizes
Wishes from
more personal freedom Wishes
for more high-quality law and order
PAIR-BONDING STYLE
AND SPOUSAL DOMINANCE
After an
upset with spouse, needs to be alone After upset with spouse, needs closeness and to talk
Tolerates
mate defiance in private Finds
it difficult to tolerate mate defiance in private
Needs
little physical contact with mate Needs
a lot of physical contact with mate
Prefers
monthly large reassurances of love Likes
daily small assurances of mate’s love
Tends not
to be very romantic or sentimental Tends
to be very romantic and sentimental
Thinks-listens
quietly, keeps talk to minimum Thinks-listens
interactively, talks a lot
Does not
read other people’s mind very well Good at knowing what others are thinking.
Often feels
mate talks too much Feels
my mate doesn’t talk or listen enough.
Often an early
morning person Often
a late night person
However, because of
the well-known complexity of individual differences, the robustness with which
any one of these twenty eight dyad pairs was tied to individual hemisphericity
was at the level of about four chances out of five. Thus, individuals varied greatly regarding as
to specifically which of each of these 28 questionnaire dyads they selected as
“the most like themselves”. For example,
about 4 of 5 early morning types were L-bops, yet 20% were R-bops, a
significant number. Although one of the
latter hypothetical R-bop subjects could assert that hemisphericity was a false
concept because they were an early rising individual, nevertheless their
assertion would certainly be incorrect [45].
Not only did each dyad significantly parse with hemisphericity brain
side overall, but also each individual’s overall balance of answers
significantly fell on the hemisphericity side that was predominant in the four
biophysical methods for hemisphericity [21-25], and was anatomically (MRI)
confirmed as the brain side with the larger ventral ACC gyrus in 97% of 113
cases [46].
In Table 2, these 28 dyadic choices were
tentatively condensed into generalizations that appeared to bring order to
these diverse topics. That is, 1) in
terms of logical orientation, L-
bops, regardless of sex
tended to select questionnaire preferences indicating a top-down,
important-details, deductive type of
logical orientation, proposed to be inherent within the local processing nature
of the left cerebral hemisphere [47,48].
In contrast, R-bops, regardless of sex, selected preferences indicating
a bottom-up, big-picture, inductive type of logical orientation congruent with
the proposed distributed organization of the right cerebral hemisphere [49,50].
Regarding
hemisphericity differences in, 2) consciousness type, the L-bops selected
questionnaire preferences indicating a verbal, less visual, rather abstract
reasoning orientation that again tended to focus upon the differences (top
down) between objects. On the other hand,
R-bops made choices suggesting highly visual, concrete reasoning that
emphasized commonalities (bottom up) between objects.
As to
hemisphericity subtype differences in 3) sensitivity level, L-bop preference
question choices indicated a sensitive, cautious, taciturn, emotion avoidant
orientation, suggestive of a relative thin barrier to fear-invoking
subconscious forces. In contrast, R-bop
choices suggested a less sensitive-more intense, bold, and talkative emotional
orientation, suggestive of a thicker barrier to these elements. In terms of 4) social orientation, L-bops
preferred answers suggesting an independent, avoidant, and competitive nature
of a subdominant individual, as
Table 2:
Summary of Hemisphericity-Dependent Behavioral Differences based upon
Preference Questionnaire Responses (n = 111)
|
Category |
L-bops |
R-bops |
|
Logical
Orientation |
Top-down, details, deductive |
Bottom-up, big-picture, inductive |
|
Type of
Consciousness |
Verbal, abstract reasoning, finds
differences between objects |
Highly visual, concrete reasoning finds
commonalities of objects |
|
Fear Level and
Sensitivity |
Sensitive, cautious, taciturn,
emotion-avoidant, defensive (Implies a thinner barrier to fear-invoking
subconscious forces) |
Intense, bold, talkative, Emotion-embracing, invasive (Implies a thicker barrier to
fear-invoking subconscious elements) |
|
Social and
Professional Orientation |
The independent, avoidant, private and
competitive nature of a subdominant individual |
The orderly, responsible, open and
cooperative nature of a dominant individual. |
|
Pair Bonding
Style and Spousal Dominance |
The less dominant spouse, Need separateness, quietness, Avoids
emotionality with logic. Assists the dominant spouse, Morning watch: Begins details of family
endeavors early in day. |
The more dominant spouse, Needs closeness-reassurance of the
other’s fidelity and support. Intuitive and highly directive. Evening
watch: Finishes, reviews, big-picture status of family plans. |
compared to R-bops who
answers suggested the orderly, responsible, and cooperative nature of a
dominant individual, i.e., “The buck
stops here!”, as
Finally, regarding hemisphericity
subtype differences in 5) pair bonding style and spousal dominance, L-bop
preference choices continued to show differences manifested in the previous
categories, i.e., separateness, avoidance of emotion, minimal but highly
articulate speech, tolerance of the more dominant spouse. Evolutionarily interpreted, the L-bops are
the early risers who tend to take the “early watch” role, so to speak,
attending to the details of the family endeavors at the beginning of the
day. In comparison, R-bops appear to be
the more dominant spouse, needing-demanding continual reassurance of the
other’s fidelity and support, highly directive and intuitive. Toward the end of the day, they tend to fit
the role of the “late watch”, attending to task completion, reviewing the
big-picture status of family endeavors, and planning-assigning goals for the
next day’s work of survival.
1.6.
Confusion between Sex and Hemisphericity Regarding Brain and Behavior
For the design of hemisphericity questionnaires calibrated
against the biophysics hemisphericity methods, there was no need to restrain
potential questionnaire statements topics to areas associated with lateral
brain specializations. As a result of
this freedom, many of the above behavioral outcomes that proved to be
associated with hemisphericity were unexpected.
Included among these were responses associating hemisphericity with
certain traits that are presently considered to be descriptors of sexual traits
by the lay public (stereotypes such as that women are
not analytical). Therefore, it was
paradoxical that independent studies on the relationship of corpus callosal size to hemisphericity also indicated a tradition
of conflation of sex and hemisphericity [46].
In order to understand
this problem, some background information is appropriate. Individuals differ in the number of corpus
callosum nerve fibers interconnecting their cerebral hemispheres by about
three-fold. Subject corpus callosum
cross sectional area (CCA) varies from about 3 to 11 cm2 at midline
[51, 52]. This variation between normal
individuals is illustrated in Figure 3, taken from Morton and Rafto [50]. Great
CCA similarities in monozygotic twins indicate that these corpus callosal size differences are under considerable genetic
control both in children and the elderly [53, 54]. Across subjects, neither brain size [55] nor
overall density of callosal large and small fiber
types was correlated with CCA [56].
Figure
3: Hemisphericty
vs. Sex:
Legend: Largest CCAs: 1. Right
brain-oriented female, 10.1 cm2 , 2. Right brain-oriented male CCA 9.2 cm2. Smallest CCAs: 3. Left brain oriented-male, 4,8 cm2. 4.
Left brain oriented-female, 4.5 cm2. Subjects in group were 113 Caucasian adults.
Early reports
suggested that on the average females had a larger midline CCA than
males (Holliday, et al., 1993). This has commonly been interpreted to support
the concept that
the brain of men is more “lateralized” or “specialized”
than that of women [57], thus accounting for presumed male superiority in
mathematics, as well as a higher association with aggressive behavior. Ultimately, meta-analysis of these many
reports [58, 59] found no significant overall sex differences in inter-cerebral
information carrying capacity.
After it became possible to
accurately determine individual hemisphericity, as described above, the issue
of effect of hemisphericity upon relative CCA size between became of interest,
especially in view of reports of dichotic deafness in L-bops who were predicted
to have smaller corpus callosi [24, 24]. Using quantitative MRI, it was found that the
midline CCA of 113 subjects was significantly correlated, not with handedness
or sex, but indeed with “dichotic deafness”, and even more so with
hemisphericity [46]. Indeed, right
brain-oriented individuals of both sexes had significantly larger CCAs than
left brain-oriented persons of either sex, as illustrated in Figure 4.
These hemisphericity results laid bare the underlying
basis of the previous controversy about gender and laterality. First, they explode the common myth about the
male brain being
more specialized due to its higher
laterality [57]. Rather, the CCA data
strongly suggested that it was the left brain-oriented individuals of either
sex who were more lateralized as a class than males are. Correspondingly (Figure 4), right brain
individuals of either sex were less lateralized and more broadly generalized as
a class than females traditionally were [57].
Figure 4. Effect of Sex and Hemisphericity upon Corpus Callosal Area
Legend: Caucasian
subjects, n = 113 (Morton and Rafto, 2005b).
Secondly, these findings appear to end the
controversy about which sex has the larger corpus callosum [58]. There appears to be no significant difference
between the two sexes either in mean CCA or in IQ. Here, (Figure 3) the two individuals with the
largest CCAs from among 113 subjects were a right-brained female (10.1 cm2)
and a right brain male
(9.2 cm2). Conversely, the two subjects with the
smallest CCAs were a left brained male (4.8 cm2) and a left brained
female (4.5 cm2). Each of
these individuals held higher education degrees and professorial status. Further, lack of awareness that hemisphericity
contributes to CCA makes it probable that the European studies reporting mean
CCAs for males to be larger [60] and American-Australian studies showing larger
female mean CCAs [51] were both correct.
Their disagreements could well be based upon regional population
differences in hemisphericity, an important but as yet, little investigated
topic to be considered later.
Third, it is becoming clear that members of
either sex with the same hemisphericity have more cognitive and behavioral
traits in common than do same sex individuals of the opposite
hemisphericity. This is strongly
supported by data from biophysical method-based derivative preference
questionnaires [25, 43]. Therefore, it
would appear that several, if not many hemisphericity traits are presently
being misidentified as male or female sex traits. For example, in the
Thus, current understanding and traditions of
brain laterality and gender need revision to include hemisphericity
results. As will be seen, this is
especially relevant to the theoretical basis of Female Studies and Feminism,
including the issue of what the true sexual commonalities and differences
are. For example, “The Glass Ceiling”
actually suppress R-boms as much as R-bofs (more so if they are heterosexuals), while L-bofs rise and thrive in the current L-bom
professional world. In this light,
hemisphericity can be seen to be a very
useful binary identifier, second only to sex.
1.7. Sorting
of Hemisphericity During Higher Education and in Career Selection
Having completed
a description of the individual differences of hemisphericity, we can now move to its population level
ramifications. Ideally, it would
be desirable to determine the hemisphericity of grade school children in the
various regions of the world. In the absence of this, hemisphericity distributions were recently assessed in groups of college
freshmen. This was accomplished by use
of the “Best Hand Test”, a rapidly administered and graded, two-hand line
bisection-based biophysical method relatively independent of language, culture,
or education [22]. Entering university
students (n= 392) enrolled in three lower division courses were chosen as a
reference population [39]. As indicated
by Table 4, each of these classes contained about 56% to 57% (a 1% range) of
left brain-oriented individuals. In
contrast, mean student left-brain distributions in four specialized, upper
level courses (n = 180), ranged from 35 % to 68% (a 34% range), suggesting the
occurrence of hemisphericity sorting in the process of higher education.
Table 5 illustrates the even
more pronounced hemisphericity distribution differences (a 57% range) found
within university representatives of fifteen professions (n=421) [39]. For example, of Biochemists (n=18), 83% were
left brain-oriented vs. only 17% who were right brain oriented. In contrast, among Astronomers (n = 21), only
29% were left brain-oriented while 71% were right brainers. Thus, the range of hemisphericity differences
rose significantly from only 1% within incoming college students, to 34% for
upper level students, to 54% between the 15 professions evaluated.
Table 4: Brain Hemisphericity
Distributions in University Classroom Populations (n=572)
|
GROUP percent
Participation |
N |
LEFT BRAIN |
RIGHT BRAIN |
Left- Handed |
Females |
|
Western Civilization 66 General Chemistry 86 Basic Biochemistry 79 |
228 104 60 |
57% 56% 56% |
43% 44% 44% |
13% 10% 11% |
58% 64% 49% |
|
Molecular Biology Laboratory 95 Home Economics, Family Issues 97 Architecture, Interior Design 94 Civil Engineering, Grad. Seminar 95 |
50 69 41 20 |
49% 68% 41% 35% |
51% 32% 59% 65% |
10% 13% 11% - % |
55% 88% 40% 25% |
Because the possibility of sampling error
exists for the smaller professional groups, whose size raged from 9 to 178,
mean = 29, n = 467, these data on the professions are offered with a great deal
of skepticism and caution. However,
there appeared to be an internal consistency between the subtypes of the more
left or right hemisphericity-concentrated professions. That is, primarily “top-down” professions
working at structural levels that are sub-visible, such as microbiologists,
biochemists, and particle physicists, were each found to be highly enriched
with left-brain-“important-details” oriented individuals. In contrast, the more “bottom-up”,
macroscopic professions, such as architecture, civil engineering design and
astronomy, were enriched with right brain “big picture” oriented people.
That segregation of
hemisphericity types continues beyond career selection within professional
sub-specialists was illustrated by the
data on the civil engineers (n = 45), as indicated in Table 6, where the design
civil engineers were much more right brain-oriented than their predominantly
left brain-oriented production civil engineer colleagues [39]. This observation directly bears upon the
well-known traditional tension between production
civil
Table 5: Brain Hemisphericity
Distributions within Populations of Fifteen Professions (n=421)
|
GROUP percent
participation |
N |
LEFT BRAIN |
Left Males |
Left Females |
RIGHT BRAIN |
Right Males |
Right Females |
|
Unsorted College Entrants |
228 |
|
|
|
|
|
|
|
Western Civilization students
62 |
228 |
57% |
19% |
38% |
43% |
22% |
21% |
|
Specialist Populations |
422 |
|
|
|
|
|
|
|
Microbiology Professors
74 Biochemistry Professors
95 Physics (particle)Professors
80 Philosophy Professors
73 Mathematics Professors
93 |
14 18 15 11 27 |
86%* 83%* 73% 73% 70% |
72% 72% 73% 54% 70% |
14% 11% 0% 19% 0% |
14% 17% 27% 27% 30% |
14% 17% 27% 27% 30% |
0% 0% 0% 0% 0% |
|
Accountancy Professors
75 Law Professors
83 Art Professors (vs.
Artists) 92 Civil Engineering Professors
89 Clin. Psychologists
(yel. pages) 75 |
9 19 27 17 29 |
67% 63% 63% 53% 52% |
44% 32% 38% 53% 24% |
22% 31% 25% 0% 28% |
33% 37% 37% 47% 48% |
22% 21% 29% 41% 28% |
12% 16% 8% 6% 20% |
|
Electrical Engineering Profs.
75 Physicians (Medical Students)
80 Mechanical Engineering Profs. 75 Architecture Professors
100 Astronomy Professors
66 |
16 178 9 12 21 |
50% 49% 44% 33%* 29%* |
50% 25% 33% 26% 30% |
0% 24% 11% 4% 0% |
50% 51% 56% 67% 71% |
44% 26% 56% 61% 60% |
6% 25% 0% 9% 10% |
* p
<0.05. (yel.
pages) = American Psychological Society members advertising in the yellow pages
of the
engineers vs. design civil
engineers [63, 64]. It is now possible,
and would of interest, to compare other sub-specialists, such as within the
practice of medicine and law, in terms of
further brain
hemisphericity segregation within those professions.
On
still another topic, less than half of the entire student-professional
population subjects at the university were correct in assessing their own brain
hemisphericity. Yet, self-assessment by both the right brain-oriented college
freshmen and professionals was more accurate than that of the left
brain-oriented members of both groups, consistent with the concept of a more
Table 6: Brain Hemisphericity in Civil Engineering Sub-Specialists and
Architects
|
Group |
N |
Left Brain- Oriented |
Right Brain- Oriented |
|
Faculty Civil Engineers Practicing Civil Engineers |
17 45 |
53% 56% |
47% 44% |
|
Practicing Construction Civil Engineers Practicing Design Civil Engineers |
27 18 |
74% 39% |
26% 61% |
|
Practicing Architects Faculty Architects |
13 12 |
38% 33% |
62% 67% |
introspective orientation for
R-bops. Reassuringly, self-assessment
accuracy for brain hemisphericity did improve with maturity for both groups
[39]. These differences were significant
(p<0.02).
An explanation was proposed to account for the sorting of hemisphericity
in higher education and career selection [39].
That is, sorting occurred as the result of R-bops and L-bops doing what
they liked best. Topics at which each
excelled relative to the other resulted in one hemisphericity subclass doing
well or poorly compared to the other.
Rewards from success or difficulty or failure shaped individual opinion
of the liking or dislike of specific topics.
This led to the selection of topics bringing personal success and to the
avoidance of those bringing failure.
Thus in general, it appears that one ends up being an architect or a
microbiologist simply by doing what one enjoys best.
Six useful conclusions are among those that
can be derived from the preceding sections of this review: 1. Research now supports the view that, due
to the unilateral nature of the executive system, the existence of
hemisphericity is inevitable. 2. Quantitative methods have been developed to make
it possible to assess any person in terms of their probable right or left brain
orientation. 3. A primary standard has been discovered that
enables the absolute hemisphericity of an individual to be determined, based
upon anatomical landmarks within the brain.
4. A number of the many
“either-or” traits that separate the cognitive and behavioral styles of R and
L-bops have been identified, most of which have no known ties to brain
asymmetry as yet. 5. Methods now exist
which can determine the average hemisphericity of groups with considerable
sensitivity. 6. The recognition of the quantifiable existence
of hemisphericity as a second dyadic personal identifier after sex carries
profound genetic implications that can bring new clarity to human behavior. Thus, it appears that the time has come for
lateral behavior studies to thrive once more, this time based upon more quantitative foundations.
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