Graviception

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2004, 2015
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Abstract

This article reviews some interesting research by Lackner and Jeka into the use of light touch to help subjects maintain their balance. The subjects’ balance was challenged by requiring them to adopt ‘tandem stance’ (with the feet placed one in front of the other, heel to toe). The experimental evidence demonstrated the importance of light touch in helping people with and without sensory impairment and with and without the use of a cane to maintain their balance in these circumstances. Light touch was found to be as effective as support in maintaining balance. Touch was explored both It follows the author’s personal experience in the teaching situation. The concept of ‘poise’ is briefly discussed before the experimental evidence is reviewed. The need for Alexander teachers to recognize the importance of light touch in the teaching situation is indicated.

About the author

See the author web-page at Alexander Studies Online: www.alexanderstudies.org/author/glenna-batson

Correspondence

Email: glenna.batson@gmail.com

Copyright

Copyright © Glenna Batson, 2004, 2015. All rights reserved.

Publishing history

An earlier version of this article was published in The Congress Papers: 7th International Congress of the FM Alexander Technique, edited by Anne Oppenheimer (London, STAT Books: 2004), 20-29.

This version revised by the author and made available for download as a PDF file September, 2015.

HTML version published by ASO 4th October, 2015.

A R T I C L E   T E X T

Poise is a body state achieved only by steady and carefree education of the body and the maintenance of balance. Poise is a character of repose or rest in the good body, whether it is in the relatively static positions of lying, sitting, or standing or is actually in progressive motion during the activities of life’s daily routine or of sport.

Raymond Dart[i]

Light hands and primary control

Understanding F.M. Alexander’s ingenious discoveries requires integrating behavioural sciences, arts, phenomenology, and many other disciplines. For most of my working life, my passion has been to synthesize information primarily from three broad fields: performing arts (dance), somatics (Alexander Technique, Ideokinesis, and other studies), and human movement science (particularly neuroscientific aspects). As an Alexander Technique (AT) teacher, one question that always captivated me was why teachers used light touch with students. Why not use more force? Since the teacher’s hands are not manipulative, i.e. not ‘making’ the student move, then what are they doing? One answer is simple: AT teachers are looking to encourage poise in coordinated action (use).

A poised manner of use is a function of proprioceptive guidance, not muscular force. The more lightly the teacher touches, the less likely he or she is to manipulate the student, and the less likely the student, in turn, is to resist being touched (by stiffening) or overly relax (by collapsing). I began to notice, though, that my students more readily attained poise when they engaged their own hands in activity. The more I would bring contrasting weights and surfaces into the lesson experience (e.g. by the student touching different objects or standing on differently textured surfaces), the less I needed to use my hands to encourage a poised manner of use. Also, I noticed the ease with which students were able to employ their primary control in more dynamic standing postures (such as lunge) compared with in feet side-by-side, symmetrical stance (the more common way we ask students to stand in front of the chair).

I saw that I needed to look a level deeper at current theories of dynamic postural balance and relate them to practice. The research I wish to report here is designed to help inform our work. Science helps me stay open and agile to new concepts that might deepen my understanding of Alexander’s discoveries. As artisans in the craft of coordination, AT teachers practice both an art and a science that is still evolving and opening like the ‘great cauliflower’.[ii] Going more deeply into any of the ‘nodes’ of the cauliflower expands and opens our understanding and appreciation of what Alexander unearthed. I should mention that the researchers whose work I am reporting here are not aware of the Alexander Technique, so the assumptions I am making are my own.

Poise

F.M. Alexander was revolutionary in developing a model of self-organization through learning to attend to one’s own sensations and perceptions arising out of experience in a gravitational world. Alexander is considered the ‘grandfather’ of the somatic movement in western society,[iii] and also the first somatic educator to propose that posture and movement are one continuum.[iv] Alexander was after ‘poise’, a word deriving from the Latin ‘pendere’, meaning ‘to weigh.’ The preconditions for poise are best met in gravity, where we are constantly sampling and weighing our contact with the world. Poised action has nothing to do with ‘posture’ as position. Defining upright standing as a function of mechanical alignment in which one’s centre of gravity (mass) stays within the base of support is insufficient. Instead, poise is reflective of dynamic postural control (i.e. balance),[v] a unified, ongoing response to gravity—a flexible, adaptive process of support governed by sensory awareness and constructive thinking.[vi] Poise is achieved not by static stacking or aligning of bones, nor holding of body parts by muscular force, but rather by enlivening the relationship between perception and action. Science currently accepts that dynamic postural control (balance) includes perception-action coupling as a vital strategy in maintaining control.[vii],[viii]

Graviception

How do we know we are vertical when we stand—oriented correctly in relationship to the earth’s vertical? Both physical and behavioural scientists have deepened their understanding of balance over the last few decades. The conception of the body as a system of mechanical links and inverted pendulums (head and trunk) held together by stretch reflexes and the contractile and viscoelastic properties of muscles is insufficient to explain postural control. Two dynamic, integrated functional systems are currently identified for maintaining balance: one orienting the body to evoke anti-gravity support, the other providing perception-action coupling.[ix]

Dynamic postural control requires ‘sense-ability’. Our perception of our vertical is remarkably accurate under normal circumstances, i.e. those free of the influence of disease (stroke) or environmental perturbations (being on a surfboard) or anomalies (trick mirrors). Normally, we exist in a narrow cone of vertical accuracy in which we can detect 2 to 3 degrees of tilt as ‘off-centre’. The integration of multiple systems gives us this remarkably accurate measurement of our body in relationship to the environment. The combination of visual, vestibular, and somato-sensory input provides a powerful multi-systems reference for upright orientation.[x] Autonomic regulation of organs (such as the kidneys and blood vessels) also might serve as potent reference systems for balance.[xi]  Somato-sensory input refers to that information coming into the nervous system from cutaneous receptors (skin), muscle spindles and golgi tendon organs, and joint afferents. Somato-sensory input is extremely abundant (or, redundant, to use a neuroscience term), versatile, and readily available. A ‘proprioceptive chain’ of somato-sensory receptors exists from head to toe, from the extraocular muscles in the eyes to the neck, trunk, hands, legs, and feet.[xii] In a sense, we have many ‘verticals’, each one formed by different senses that are encoded and integrated in the nervous system to provide a unified spatial picture of an upright standing body in its environmental context.  AT students can experience a ‘mismatch’ in their sense of uprightness when they move away from habit—as when they find head balance and experience a conflict between what the eyes see and how the head-neck-body feels to them. In cases of disease, such as stroke, the conflict between the patient’s visual (seen) vertical and the somato-sensory (felt) vertical can make rehabilitation challenging and frustrating, since the patient might feel ‘upright’ when their body is actually tilted as much as 20 degrees.[xiii]  

Fingertip Contact

If you’ve ever tried to navigate smoothly in a dark room, you might recall that you didn’t lean heavily on the wall, but rather lightly touched the surface of the wall as you proceeded towards your destination. In fact, the more you leant passively on the wall, the more disorienting the experience. You might also recall how persons who are blind use their cane not as a physical support for the body, but rather as a telescopic ‘eye’, perceiving the ground through their fingers via the length of their cane as they walk along. In both cases, the information from light touch of the fingers (both near- and far-distance) is a powerful reference for upright balance when vision isn’t available.

Researchers Lackner and Jeka noticed this common phenomenon of navigating smoothly in the dark using light touch, and set up experimental conditions to test several theories on how light touch could improve balance.[xiv]  In their first set of experiments on ‘normal’ (i.e. non-neurologically impaired) individuals, the researchers had the subjects stand in tandem stance (heel to toe) on a force plate with another force plate located at the side of the body at waist height. The tandem stance (where one foot is placed directly in front of the other, with its heel touching the toe of the rear foot) is important, as it requires more dynamic postural control to stand this way than with the feet side-by-side (something for AT teachers to keep in mind). Three experimental conditions were tested: with hands by their sides (‘No Contact’ condition), ‘Light Touch’ (their index finger touching the force plate located to their side at waist height), and ‘Unrestricted Force’ (leaning on their finger on the force plate). The subjects were instructed to stand for 25 seconds in each of the 3 conditions with eyes open and then with eyes closed (6 conditions altogether). In the ‘Light Touch’ condition, subjects were asked to use no more than 100 grams of force in touching the plate or they would trigger an alarm. Lackner and Jeka measured centre of pressure displacement (in centimetres) of the body (i.e. the amount of body sway), centre of pressure displacement of the index finger, and electromyographic activity in the legs (EMG). They predicted that the amount of displacement of the body (centre of pressure displacement in centimetres) would be highest in the ‘No Contact’ condition, i.e., the body would sway the most, which was, in fact, the case.

With no support from the finger or other external object, the subjects’ sway was larger with eyes closed than with eyes open, as you might expect. Since the amount of light touch dictated in the experiment was far below forces physically necessary to support the body, the researchers predicted that the ‘Light Touch’ condition would make little or no difference in the amount of sway of the body (2-3% attenuation, or reduction, in sway). To their surprise, light touch was able to reduce the body sway by 50-60% in both eyes open and eyes closed conditions, similar to when the subject was given permission to lean on the finger.

It is of further interest that in the ‘Light Touch’ condition none of the subjects had to be trained in how much force to exert through the index finger. Subjects averaged less than 50 grams of force through the fingertip at the point of contact, less than half the allowed value, as they modulated the pressure whilst maintaining their balance during the 25-second stance time. This suggests there is an in-built preference to use lighter rather than heavier touch in such circumstances, making it unnecessary for subjects to learn special behaviours to fit within the experimental constraints.

Practical exercise

Try this yourself. Go to a dimly lit room that has a smooth floor. Place a chair by your right side with the back of the chair roughly at waist height. Put your non-dominant foot in front of your dominant foot, heel-to-toe. (It’s worth trying the experiment with either foot in front.) Now try the following:

  1. Stand with your arms down by your side for 25 seconds (eyes open). Rest a moment.
  2. Stand with your arms down by your sides for 25 seconds (eyes closed). Rest again.
  3. Place your right index finger on the edge of the chair back and repeat conditions 1 and 2. What do you notice when you have your index finger lightly touching the chair? What is activating in your neck and back, your legs?
  4. Finally, repeat the experiment by leaning on your finger.

Sensitivity at the fingertip

Lackner and Jeka found that even though fingertip forces alone were far below those physically necessary to stabilize the body in upright dynamic stance, the contact forces through the finger in the ‘Light Touch’ condition actually decreased as the body sway increased. Additional stabilization for the body was met by increasing somato-sensory acuity, not force![xv]

Contact with any body part might influence body orientation and dynamic postural support. When a fingertip is lacking, one might well resort to balancing via their forehead or nose, for example. The cutaneous receptors of the index finger are the most sensitive, however. The many cutaneous receptors of the fingers (slowly- and rapidly-adapting sensory afferents) provide us with incredibly precise and accurate tactile information about touch, pressure, movement, temperature, pain, and more. The fingertip can discriminate two points 2 millimetres apart. Receptor density in the feet is such that discrimination thresholds are 8 to 10 mm, interestingly the approximate mean level of sway Lackner and Jeka observed in the ‘No Contact’ condition with the eyes closed. The feet were definitely lively when the fingertip was not engaged with the force plate. The researchers hypothesized that postural trunk muscles remote from the fingertip helped stabilize the body, i.e. the fingertip receptors were providing sway-related feedback along with arm proprioceptors that triggered activation of the deep spinal muscles of the trunk. This is similar to the way a blind person might use a cane as a fingertip, i.e. as an investigatory detector and modulator of upright orientation. This they confirmed by looking at the EMG patterns in the legs, in which the lower leg muscles were most activated in the ‘No Contact’ condition, followed by ‘Light Touch’. The leg muscles were least activated in the ‘Force’ condition when the body was leaning more passively through the hand.

Subjects with sensory challenges

The researchers went on to study the same phenomenon in persons with sensory challenges: vestibular disorders and congenital blindness. Persons who have impaired function of both vestibular organs must rely strongly on vision for balance. Ordinarily, they would not be able to stand for more than a few seconds if asked to stand in tandem with eyes closed. Light touch through the index finger not only enabled these persons to stand for the same length of time as normal subjects, but also the changes in force through the fingertip actually led the body sway by 250 – 300 milliseconds. The fingertip was actually anticipating changes in sway rather than merely reacting to the sway![xvi]  Vestibular rehabilitation is a hot topic among medical practitioners. This research helps support our work in helping persons with vestibular disorders activate postural stabilizers in the trunk through light touch (from their own fingertips or from their teachers’).

In comparing subjects with congenital blindness to normal (seeing) controls, Lackner et al set up similar laboratory conditions, but using a cane that was held by the subjects both vertically (perpendicular to the ground) and slanted away from the body at an angle of 30 degrees to the ground.[xvii] All subjects were able to control body sway more readily and easily with lower force when the cane was slanted at 30 degrees (the actual plane of sway). This research indicates the importance of making clients aware of the potential of  a cane as a perceptual tool rather than just as a support mechanism.

Implications for teachers

What implications does this research have for us as teachers of the Alexander Technique? Our goal is clearly not to ‘attenuate postural sway’ but to encourage constructive conscious employment of the primary control in order to attain poised use. However, there are several important things to derive from this research and others that could help our students. First, our field already builds into lessons activities that stimulate an improved use of the primary control by engaging touch, for example ‘hands on the back of chair’, or working with activities. Bringing variation into the picture in the same lesson—through different dynamic stance positions, placing the chair in different orientations, or simply changing the texture of the contact surface (either in the chair or the feet)—might stimulate further improvements.

This is an exciting time for research in dynamic postural control, and we are coming closer to an understanding of an Alexandrian concept of ‘poise’ and how sense-ability can help us achieve it.

To quote philosopher David Applebaum:

Before poise can reveal itself, a tension that is the psychophysical milieu of accomplishment must ease…All evidence suggests that poise is not the natural outgrowth of a process that begins in distraction, preoccupation, and insensitivity.[xviii]

NOTES


[i] Raymond Dart, 'The Attainment of Poise' in Skill and Poise (London: STAT Books, 1996), 114.

[ii] ‘Be patient; stick to principle; and it will open up like a great cauliflower’: Albert Redden Alexander quoted in Frank Pierce Jones, Freedom to Change, first published as Body Awareness in Action (3rd edition, London: Mouritz, 1997 [1976]), 110.

[iii] Michael Murphy, The Future of the Body: Explorations into the Further Evolution of Human Nature (Los Angeles: Jeremy Tarcher, 1992).

[iv] Edward S. Reed, 'An outline of a theory of action systems.', Journal of Motor Behavior, 14/2 (1982), 98–134.

[v] Fay B. Horak and Jane M. Macpherson, 'Postural orientation and equilibrium' in Rowell, Loring B. and John T. Shepherd (eds), Handbook on Integration of Motor Circulatory, Respiratory, and Metabolic Control During Exercise (Bethesda, MD: American Physiological Society, 1996), 255–92.

[vi] See F. Matthias Alexander, The Use of the Self (London: Victor Gollancz, 1985 [1932]).

[vii] James J. Gibson, The Ecological Approach to Visual Perception (Hillsdale, NJ: Lawrence Earlbaum, 1986).

[viii] Keith Davids, Paul Glazier, Duarte Aráujo, and Roger Bartlett, 'Movement systems as dynamical systems: the functional role of variability and its implications for sports medicine', Sports Medicine, 33/4 (2003), 245–60. 

[ix] Jean Massion, Alexei Alexandrov, and Alexander Frolov, 'Why and how are posture and movement coordinated?', Progress in Brain Research, 143 (2004), 13–27.

[x] Lewis N. Nashner and Gin McCollum, 'The organization of human postural movements: a formal basis and experimental synthesis', Behavioral Brain Science, 8 (1985), 135–72.

[xi] Horst Mittlestaedt, 'Origin and processing of postural information', Neuroscience and Biobehavioral Reviews, 22 (1998), 473–78.

[xii] Jean-Pierre Roll and Régine Roll, 'From eye to foot: a proprioceptive chain involved in postural control' in B. Amblard, A. Berthoz, and F. Clarac (eds), Posture and Gait: Development, Adaptation and Modulation (Amsterdam: Elsevier, 1988), 155–64.

[xiii] Hans-Otto Karnath, Susanne Ferber, and Johannes M. Dichgans, 'The origin of contraversive pushing: Evidence for a second graviceptive system in humans', Neurology, 55/9 (2000), 1298–1304.

[xiv] John J. Jeka and James R. Lackner, 'Fingertip contact influences human postural control', Experimental Brain Research, 100 (1994), 495–502.

[xv] John J. Jeka, 'Light Touch Contact as a Balance Aid', Physical Therapy, 77/5 (1995), 476–87.

[xvi] James R. Lackner, Paul DiZio, John J. Jeka, et al., 'Precision contact of the fingertip reduces postural sway of individuals with bilateral vestibular loss', Experimental Brain Research, 126/4 (1999), 459–66.

[xvii] John J. Jeka, Randolph D. Easton, Billie L. Bentzen, and James R. Lackner, 'Haptic cues for postural control in sighted and blind individuals', Perception & Psychophysics, 58/3 (1996), 409–23.

[xviii] David Applebaum, The Stop (Albany, NY: SUNY, 1995), 15.

Comments

In this article, Batson has coined the term 'graviception' to characterize our ability to sense the vertical, both statically and dynamically. This locution easily leads the reader to assume that we are able, through various aspects of neuro-musculo-skeletal structure, directly to sense the direction of gravity, and to respond to it. At least one leading authority does not believe this to be the case. I refer to T. D. M. Roberts, who, in his article 'Problems in the Understanding of Locomotion and Balance in Man',[1] points out that we are actually responding to stress forces––with associated accelerations, displacements, and pressures in the body––generated not by gravity per se, but by our points of contact (or not) with the earth, resulting in what he calls the 'behavioural vertical'.Of course, fully to understand this view of things would require close reading of his article, or of the relevant sections of his Understanding Balance: The Mechanics of Posture and Locomotion.[2] But without pressing the point further, I suggest that Batson would be on safer ground to speak of 'vertiception' rather than 'graviception'.

Another point is that Batson uses the term 'primary control' four times without further defining or clarifying what she understands by it, as if all readers would (or should) already know what she means. And yet in my 'Primary Control and the Crisis in Alexander Technique Theory',[3] I documented nine markedly different conceptions of this phrase as used by Alexander teachers, suggesting that we, as a professional community, hardly do have a common understanding of this supposedly foundational concept. My own definition, in 'Defining Primary Control', is 'Primary Control: the process, as primary task, of bodily adjustment to gravity'. [4] Like it or not, at least when I speak of 'primary control', this is what I mean. Agreeing on common language, regardless of the necessary experiential dimension of all ideas, is a basic requirement for professionalism that has not yet been achieved, or hardly even collectively confronted, in the Alexander Technique.


[1] In Proprioception, Posture and Emotion, edited by D. Garlick (CPME [Committee in Postgraduate Medical Education]: University of New South Wales, 1981), 142–153.

[2] London: Chapman and Hall, 1995.

[3] AmSAT News, 45, Summer 1999. Also in my Alexander Revisited: Contemplation and Criticism 1979–2014 (Atlanta: Posturality Press, 2014), 21–32.

[4] AmSAT News 64, Summer 2004. Also in my Alexander Revisited: Contemplation and Criticism 1979–2014 (Atlanta: Posturality Press, 2014), 51.

Thank you for commenting on the Graviception article. I appreciate your critique and am pleased that ASO provides the kind of venue for open discussion and dialogue.

I based my article on a presentation I made at the Oxford Congress in 2004. Thus, it wasn’t so much to explain ‘graviception’ for a peer review scientific journal, but simply summarized a series of speculations I was making at the time about our pedagogy concerning the use of light touch in teaching. No doubt, AT teachers use light touch for multiple reasons. For one, it is effective in drawing conscious attention to the extraordinary degree of human sensitivity for ease and coordination in a gravitational world. In this regard, I also might have discussed the Weber-Fechner law from psychophysics. This law quantifies the perception of change in a given stimulus, or, in layperson’s terms, speaks to the fact that tactile sensitivity increases as force decreases. Perception of one’s body in space appears to decrease as force increases. It is easier to notice a fly on one’s arm than the compressive force of body weight on the spine. In this article, however, I based my choice of the word ‘graviception’ explicitly how it was used by Lackner and Jeka, Mittlestaedt, and Roll and Roll, who refer to somaesthetic receptors throughout the body that cue humans about space and place.  In any event, I look forward to reading T.D.M. Robert’s piece (1981), in order to reflect on your clarification.

Human beings' communication with gravity is not only in relationship to a vertical orientation. Rather, humans sense gravity by means of multiple biological ‘mechanisms’ that enable grounding and expansion of our bodies, regardless of orientation. This ‘sense,’ ‘capacity,’ or ‘homing mechanism' is both innate and cultural. Colloquially, I would say that humans need ‘a wink and a blink’ to know where they are in space – one that is automatic and one conditioned by culture and context. I refer to the vertical in this article primarily because Lackner and Jeka’s experiments were conducted in vertical stance. Their concept of graviceptors is discussed primarily in regards to receptors in the skin and spinal muscles.

As for primary control, I agree with you wholeheartedly for the need for consensus on a definition within our profession. I would sincerely applaud your efforts to resurrect this topic within our circle for discussion and debate.

During my presentation, my use of the term ‘primary control’ was very much in line with AmSAT’s: ‘The relationship among the head, neck and back is what F.M. Alexander called the primary control. The quality of that relationship—compressed or free—determines the quality of our overall movement and functioning’ ( http://www.amsatonline.org/faq#t17n687).  

Here we are, 11 years later, and by now, my understanding of ‘graviception’ has expanded to embrace more than a series of biological mechanisms for communication with the world. If I were to write the article today, I would be drawing more from cognitive and affective neuroscience which would say that unified thought and action is best described by a series of E words: embodied, embedded, extended, emergent, enactive and empathetic (Hutto and McGivern, 2015).  Perhaps we need to abandon the term primary control for embodied consciousness? (Thompson and Varela, 2001).   


References

Hutto, Daniel D. and Patrick McGivern (2015), ‘How embodied is cognition?’, The Philosophers’ Magazine, 68/1, 77-83 <http://www.overcominghateportal.org/papers-embodied-cognition.html>.

Thompson, Evan and Francisco Varela (2001), ‘Radical embodiment: Neural dynamics and consciousness’, Trends in Cognitive Sciences, 5, 10 < https://evanthompsondotme.files.wordpress.com/2012/11/thompson-varela-tics-2001.pdf>.

[From David Gibbens:

Following discussions between myself and Michael, this comment was first removed (November 2015) and subsequently republished (June 2016).  It was resubmitted in the meantime as an indepedent article subject to community review.] You'll need to be logged in with Contributor status to read it.

Thanks to Glenna and Ron for leading the way on this important discussion of gravity and human verticality. 

As students and teachers of the Alexander Technique, our paramount interest is in improving the quality of our functioning and helping our students do the same. I consider gravity and verticality in this context. 

One thing seems clear. Human beings are able to maintain a functionally vertical head/neck on a very consistent basis. The brain/body processes that support this ability work very well. Only a very extreme occurrence disrupts it. Of course, this doesn't speak to the quality or efficiency of our uprighting, only to the end that is gained. Even a person stooped over with an over-flexed thoracic spine and a pulled-back head, is successfully uprighting. He may be doing it poorly but he is far removed from being a pile of flesh and bones on the ground. He continues to create a functional, and relatively vertical, head/neck. I think it is very important to recognize the inevitability of our uprighting. No matter the means required, we always find a way to get it done. 

Ron defines "primary control" as "the process, as primary task, of bodily adjustment to gravity." I agree with the "primary task" part. But, as I see it, this task does not include "adjustment" to gravity." Gravity, as it relates to motor coordination, is nothing more than the movement of our body mass straight down towards the center of Earth. We have been so moving since the moment we were conceived. We don't need to "adjust" to it. 

What is the practical impact of our body mass being compelled down by gravity? 

To counter the notion that we "directly..sense the direction of gravity and [then]...respond to it," Ron paraphrases Roberts' view that "we are actually responding to stress forces––with associated accelerations, displacements, and pressures in the body––generated not by gravity per se, but by our points of contact (or not) with the earth." [my emphasis]

Our points of contact with the earth are determined by the downward trajectory of our body mass. Each of us, individually, controls this trajectory. Different trajectories create different skeletal ground contact points and, in turn, different uprighting responses. The source of the "stress forces -- with associated accelerations, displacements and pressures in the body" is the combination ofon the one hand, the trajectory of our downward moving body mass and, on the other, the ongoing, inevitable, "primary task" of lifting this same body mass into verticality. This is push coming to shove.

Glenna says that there is an "extraordinary degree of human sensitivity for ease and coordination in a gravitational world." I agree. What enables this "ease and coordination" is our ability to allow gravity to move our body mass straight down to earth. It is through allowing this straight-down influence of gravity that we optimally capture and harness the energy of our body mass, establishing optimal ground contact that enables our deepest extensor muscles to lift us with optimal efficiency.

Glenna says: "[H]umans sense gravity by means of multiple biological 'mechanisms' that enable grounding and expansion of our bodies...This 'sense,' 'capacity,' or 'homing' 'mechanism' is both innate and cultural. Colloquially, I would say that humans need 'a wink and a blink' to know where they are in space - one that is automatic and one conditioned by culture and context."

I find valuable Glenna's distinction between innate and culturally conditioned aspects of the "biological 'mechanisms' that enable grounding and expansion of our bodies." 

Gravity's straight down influence on body mass is obviously innate and automatic. It affects all creatures on Earth. Every animal is born with the natural movement ability particular to his/her unique species. All lions move as lions, bears as bears. Human beings are no different. We are all born to upright easily and gracefully -- to create the optimal "grounding and expansion of our bodies." It is our "primary task" -- a skill that has evolved over millions of years. 

Innate uprighting works in a specific, particular way -- the same for all human beings. Gravity's straight-down influence is the linchpin. All of us as infants and toddlers learn to upright beautifully on our own, without being taught by anyone. We do so by being sensitive to our body mass, by allowing gravity to take it straight down. This enables us to capture its power and use it to our uprighting advantage.

But, alas, we cannot avoid being "conditioned by culture and context." Beginning in infancy, while in the midst of manifesting the uprighting wisdom of the ages, we are at the same time witnessing everyone around us constantly sitting back in chairs, sofas, car seats, etc. This makes an indelible impression. We learn from society that it is normal and appropriate to attain head/neck verticality while throwing our weight backwards. By age 5, it has become standard operating procedure. Trouble is, sitting-back imposes an other than straight down trajectory on our body mass. This is direct and blatant interference with gravity's straight down influence. This causes big problems since gravity's straight-down influence is an essential element of one of our supreme inheritances -- the ability to upright effortlessly. 

Leaving our toddler period, we develop the musculature to support mis-use. As our sensitivity to our weight declines and our "weight mis-commitments" become habitual, the act of uprighting becomes a lot more stressful. Our head-neck-back relationship becomes decidedly less free, full of muscular strain and skeletal distortion. Yet, as young children, we make a seamless transition from the innate to the habitual. We don't notice the change, or have any recognition of having lost something important. Please see my illustrated essay, Habitual vs. Innate Sitting -- A World of Difference at www.uprighting.com/sittingessay.pdf.

F.M. Alexander taught us that when we act habitually, directing ourselves subconsciously, we lose access to the live sensations present in the performance of that activity. This results in our using means far less than optimal. What's worse, because habitual activity feels 'right' to us, we are blind to our mis-direction and degraded use. This is basic Alexander Technique theory. And it describes perfectly our sitting-back habit.

 Thanks for your attention.

 Michael

Just to note that the full text of the article has now been added to the web-page of the bibliography entry, so you can  read the article  online here. Previously the article was only available as a PDF download. Given that the comments are appearing online, it seems appropriate to make the article itself available in the same way.

A quirk of the conversion process has been that end-note references now appear as Roman numerals. I don't know why; but I can't justify spending the time to convert them back to Arabic numerals so I am leaving them as they are.

I welcome Ron's commitment to finding appropriate terminology, as expressed in his comment above.  As Editor I do look carefully at the wording of pieces that are presented for publication and suggest corrections where this seems appropriate in the interests of precision.  More generally, I have hoped that ASO will provide a space where a shared understanding of terminology, and appropriate and inappropriate uses thereof, can be developed.

Until recently, I had thought of this process of clarification and growing precision as being an organic outgrowth of debate. Increasingly I think there may be a value in relevant definitions and usages being captured in the so-called 'Alexander Encyclopaedia', which I have seen as one of the resources offered (eventually) by ASO. This could function both as a catalyst for the necessary debate and also as the repository for the final (or perhaps I should say provisional) outcome of that debate. Obviously, terms like 'primary control' would warrant such a treatment: but so too would terms such as 'force', 'energy', 'weight', 'balance', 'posture', 'poise'—even 'falling'.

Specifically on the terms 'graviception' and 'vertiception', I'd like to make a number of points. The first is that I think Ron, in coining the term 'vertiception' has done us, and the wider scientific community, a considerable service. It is a useful neologism. Unlike 'graviception', which is a term already in use (of which more below), the term 'vertiception' did not previously seem to exist. When I googled for it, the only results that came up were from Alexander Studies Online (we have since been supplanted from the top of the list by a link to a youtube video....). So Ron has conferred 15 minutes of fame on ASO (provided you are looking for the term 'vertiception' of course).

As Ron points out, the term 'vertiception' alludes to the fact that our sensory systems are oriented towards gauging the 'behavioural vertical' rather than gravity itself. This is not the place to discuss the behavioural vertical in detail: but the essential difference when thinking of it is that it brings into the equation inertial forces. If you think of a fairground ride, the effects of gravity are constant throughout; but the inertial forces affect us in many different directions and it is the sum total of inertial and gravitational forces that our bodies need to adapt to.  Similarly, if you imagine yourself orbiting the earth in a spacecraft, you would expect to experience weightlessness: you might, incorrectly, imagine that you were no longer in the field of gravity ('zero gravity' is indeed a term used by NASA[1]). But if we actually did have graviceptors not verticeptors then they would tell us that we were nearly as much in the earth's gravitational field—particularly in low earth orbit—as we were at ground level. We would in fact be in free fall towards the earth - but because we are also moving forwards at several thousand miles per hour the combined trajectory means we never hit it: we go round it instead. We experience the fact of weightlessness, brought on by free fall, and the illusion of zero gravity (and I had better add, as a non-scientist, 'correct me if I am wrong').

Graviception

It should be noted that, whereas Ron has said that Glenna has 'coined' the term 'graviception', this is not the case as, again, you can discover using google or another search engine. Moreover, scientists that use the term do also clearly recognise that 'graviceptors' do not detect gravity as such. For example, Mittelstaedt, in a research paper entitled Somatic Graviception, notes in his 'Introductory Summary'

An organ that is sensitive to gravitational force is also sensitive to force caused by translatory acceleration. As a matter of fact, it cannot discriminate between the two types of force, because they are identical (Einstein, 1916).[2]

For a more detailed and focused discussion on what our detectors detect, I would suggest referring to the works of Tristan Roberts (as Ron has done - but see end-note).[3]

In the context of her article, Glenna's use of the term 'graviception' is reasonable: it is a term in accepted use. It would not have been an appropriate editorial intervention to challenge it in the absence of an alternative which, until Ron's contribution, I did not have. Moreover, as she points out in her response to Ron, the article is not 'about' graviception in any general sense; in fact the term scarcely appears: it is just a rather catchy title.  If Glenna were to republish the article I might consider suggesting to her she adopt Ron's term vertiception; but on the other side of the argument, changing the title of an article could legitimately be deprecated as diminishing the reliability of the scholarly record if the article were essentially the same.

Were I to move forwards with the Alexander Encyclopaedia to the extent of including the terms under discussion, I would suggest that 'vertiception' and 'verticeptors' would be the preferable term. That said, by most standards, 'vertical' means 'in the plane of gravitational forces', so it would be important to emphasise the additional 'behavioural' dimension associated with the terminology. 


NOTES

[1] See for example http://www.nasa.gov/centers/glenn/about/grcfaq.html#antigrav. Tristan Roberts criticises this usage of the term 'zero gravity' by NASA in Understanding Balance (London: Chapman & Hall, 1995), 10.

[2] Horst Mittelstaedt, 'Somatic Graviception', Biological Psychology, 42 (1996), 53-74, p. 55. This is downloadable in its entirety as a PDF if you search carefully. It bears an interesting relationship to Glenna's article, given that the subject matter is yet another set of 'verticeptors'.

[3] Ron refers to Roberts' contribution in David Garlick's Proprioception, Posture and Emotion. Unfortunately, that book is no longer available either new or secondhand at the time of writing. Understanding Balance (see endnote 1) is no longer in print but secondhand copies are available, often at reasonable prices.

Roberts' The Neurophysiology of the Postural Mechanisms (London:Butterworths,1967 [1st Edition], 1978 [2nd Edition]) may also be of interest but can be expensive to acquire; moreover, there are nearly 20 years between the 2nd edition and Understanding Balance: Roberts' thought may have moved on in the interim. Interestingly, between the 1st and the 2nd editions of Neurophysiology..., the aspect of graviception versus vertiception seems to have become of particular interest to Roberts. He notes in the Preface to the 2nd edition:

'I have found it most enlightening to shift the emphasis, in dealing with the otolith organ, from gravity to elastic stress, with widespread consequences throughout the book' (p. v).

This touches on the need to think in terms of inertial forces in addition to gravity.

Given that a further 20 years have elapsed since the publication of Understanding Balance it would be of interest to identify any further useful references.