Equilibrium, modularity, and training the brain-body

Blogging on Peer-Reviewed ResearchRetaining one’s balance in movement is one of the more complicated sensory and motor tasks that humans routinely accomplish.  Elite athletic activities make the task of maintaining bipedal locomotion all the more difficult; no other species, I would argue, not even the kangaroo or gibbon, engages in a repertoire of bipedal activities even remotely close to as varied as that of humans.  We walk, run, skip, hop, and combinations of all three; we kick while running, jump over a range of obstacles, cross balance beams and tight ropes, ride unicycles; some of our species even juggle soccer balls, play badminton and volleyball with our feet (no kidding, in Brazil I used to see futevolei — ‘foot-volleyball’ — on the beach… amazing), balance objects on our feet and a host of other activities.  And, in the example I want to start discussing, some of us even invert our bodies and become bipedal on our hands, sometimes to extraordinary effect.

In order to accomplish these sorts of tasks, we use our ‘sense of balance.’  I hesitate to call it a sense, though, because the systems of perception, forms of analysis that we do, and reactions that we use to preserve our equilibrium are actually a complicated system, a set of shifting constellations of interio- and exterioceptions, differently weighted and compared depending upon our environment and task, and a host of active patterns of physical compensation, most of them only vaguely conscious, at best, that keep us upright.  Equilibrium is a perceptual-motor system in the sense discussed by James J. Gibson (1979), perhaps even more baroque the visual perception system (his favourite example).

Minimally, a brief ecological psychology of balance would need to include at least the following: the vestibular system; information from the visual system including the horizon line, parallax, relation of centre of field of vision to visual references, and movement in peripheral vision; sensations on the soles of the feet as well as at joints and other forms of proprioception; sense receptors at the back of the neck as well as a sense of the head’s alignment in space and in relation to the body; the gravity-resisting muscles, usually those of the lower body, and the reflexes that move them to compensate for perturbations in balance.

The vestibular system is itself a combination of five different sensory organs on each side of the head embedded in the temporal bone.  Three semicircular canals (the superior, posterior, and lateral or horizontal canals) together with the utricle and saccule form the vestibular system.  The semicircular canals are each maximally sensitive to motion in the plane of the canal as their acceleration will stimulate the end of the canal, the ampula, where the sensory organ is located; they detect angular acceleration or changes in direction.  Canals are also paired so that rotation in their plane will excite one while inhibiting the other.  The otolithic organs—the utricle and saccule—are sensitive to the body’s linear acceleration in space or any speeding up or slowing down of the body, as well as to the head’s position in space.

In spite of this complexity, Jerry Fodor, in his collection, The Mind Doesn’t Work That Way: The Scope and Limits of Computational Psychology (2000), makes a passing suggestion about the sense of balance that made me, as a scholar of physical education, sit up(right) and take notice.  Although he only makes the remark briefly, in a footnote, it is worth reproducing:

…there is a new contender for “best example of a module”: the apparently domain-specific, encapsulated mechanism that many vertebrates, people included, use to recover from spatial disorientation.  For some really rather stunning experimental results, see Cheng and Gallistel (1986); Hermer and Spelke (1996).  (Fodor 2000:118, fn. 9)    

Fodor is the State of New Jersey Professor of Philosophy and Cognitive Science at Rutgers University and has been called the ‘leading philosopher of mind in the world today’ by Colin McGinn (author of the wonderful piece, among others, ‘Can We Solve the Mind-Body Problem?’ Spoiler: McGinn says ‘no’). Following especially on the linguistic work of Noam Chomsky, as well as evidence from illusions, Fodor produced one of the most powerful arguments for a “modular” approach to mind in his 1983 book, Modularity of Mind. It’s a great book — clever, well written, powerfully argued — and in it, Fodor argues that the mind is made up, at least in part, of innate ‘modules’ with the following traits:

1. Encapsulation: they need not get outside information to operate and they tend to be relatively inaccessible to other processes, such as conscious reflection.  As Foder explains: ‘Information flow between modules—and between modules and whatever unmodularized systems the mind may contain—is constrained by mental architecture’ (1998:127).  In particular, Fodor wants to say that what we think or believe cannot affect how certain parts of our minds function.

2. Inaccessibility: Consciousness generally cannot get access to modularized thought processes.  ‘Just as information about beliefs and desires can’t get into a module, so the information that is available to its computations is supposed to be proprietary and unable to get out.  In particular, it is supposed not to be available for the subject’s voluntary report’ (ibid.).

3. Domain specificity: Modules are specialized to work only on certain kinds of inputs, and they do not all work alike or have access to the same functions, so that face recognition or speech or spatial perception may not work the same way in the mind.

4. Innateness: ‘The information and operations proprietary to a module are more or less exhaustively “genetically preprogrammed” (whatever, exactly, that means)’ (ibid.:128).

Modules, because they have these traits, are fast, dependable, relatively uniform (among individuals), heterogeneous (in the sense that different modules function in diverse fashion), and can’t usually get stuffed up by our own crazy ideas about how our brains should work or even by lousy teaching or training (because they are immune to conscious thought). The modules concept has been picked up by a number of scholars, such as Steven Pinker, Harry Plotkin, and Leda Cosmides and John Tooby, but Fodor has often been at pains to distance himself from some uses of the concept he has done so much to bring into contemporary discussions of the philosophy of mind. For example, Fodor has been scathing in his critique of some ‘evolutionary’ arguments for the emergence of particular modules and of some arguments that the brain is ‘massively modular,’ most of its functions handled by specialized parts (see Fodor 2000 for some of his rather bruising reviews of other scholars’ work).

On its face, the claim that ‘recovery from spatial disorientation’ might be under the control of a brain ‘module’ may seem to be relatively good one. In fact, equilibrium recovery does demonstrate some of the traits that we expect of a module as defined by Fodor: the process is fast, not terribly subject to conscious examination (although I would like to complicate this), and seemingly automatic. The vestibulo-spinal reflex, that is, the reflex that causes us to resist a fall, or prepare for a crash landing by yanking back our head and throwing out our arms, displays a kind of stereotypy, automaticity, and pervasiveness that advocates of pre-programmed modules do seem to love.

Leaving aside the criticisms of ‘modularity,’ some of which I find extremely persuasive (see, for example, Karmiloff-Smith 1992; Uttal 2003; and Barrett and Kurzban 2006), I just want to look at evidence about the system of equilibrium and the ‘new contender for “best example of a module”’ (well, ‘new’ as of 2000). In fact, I think that there is very strong support for the proposition that brain functions are localized, although they generally are more distributed in networks, and even that some mental processes have certain traits that Fodor labels as conditions of ‘modularity,’ but I am not persuaded by evolutionary arguments for the emergence of modules — in part due to Fodor’s stinging criticisms — nor by the argument that all mental modules are innate. Instead, it seems clear from the evidence that even very ‘specialized’ parts of the brain (such as face recognition, a favorite function of people arguing for modularity) emerge from the organisms active, unfolding development, emerge in a variety of ways, and can be mobilized to do other functions when driven by extreme training or conditions.

For example, some parts of the brain that seem to be most active with face recognition tasks (the neuro-architectural candidate for the site of a ‘face recognition module’) turn out to be used by bird watchers and avid car collectors for recognizing the objects of their own fascination. With this evidence, it’s hard to say that this part of the brain is ‘for’ face recognition; it may usually get used to recognize faces, but it’s clear that, given certain kinds of developmental regimens, it may get co-opted to do other things. More radical research on animal subjects has even shown that audio cortex that is surgically connected in newborn ferrets to visual nerves can ‘learn’ to interpret visually information (by Mriganka Sur of MIT – an article from The New York Times on his research).  For this reason, I think Karmiloff-Smith’s argument about ‘modularization’ is more persuasive than assertions about ‘innate modules’ that argues for the predestination of neurons.  There’s just not enough genetic information in our DNA, nor do embryological development processes look like they could create such pre-ordained tissues (again, Oyama 2000, is good on this topic).

Ironically, one of the pieces that Fodor refers to in his discussion of equilibrium, a 1996 article in Cognition by Linda Hermer and Elizabeth Spelke, also showed that adults oriented themselves using a conjunction of different sources of information, some of which infants (and apparently rats) could not or did not use to reorient. Far from being a case for strict ‘predestined’ modularity (which Fodor may be seen to imply with ‘innateness’), then, Hermer and Spelke’s (1996) work might instead be seen as a demonstration that the mature assembly of information and reflex action in the adult equilibrium system took time and training to emerge (and thus might be subject to different factors that would influence how it emerges).

Is this, in fact, much more what the equilibrium system itself looks like?

The evidence seems very clear that the sense of balance (again, with all the caveats of calling it ‘a’ single ‘sense’) can be trained to wide range of different challenges and to operate more efficiently or from different sets of information depending upon the task constraints. The variability of equilibrium was driven home to me in my research on capoeira, an Afro-Brazilian martial art and dance (which I will discuss in the second post on equilibrium).

Fodor points to equilibrium maintenance as a strong candidate for status as a ‘module’ (mind you, some of the advocates of ‘massive modularity’ have moved beyond ‘best candidate’ to assuming that all mental functions are modular; see, for example, Steven Pinker’s work). The enormously varied input feeding into the equilibrium system and its ability to contend with a variety of different circumstances by quickly shifting how it interprets, weighs, and responds to sensory information suggests that, if equilibrium is a ‘module,’ it must have access to a lot of information, shift which sources it prioritizes, and be able to acquire responses that are hardly ‘innate’ (for example, staying upright on the deck of a boat, or while spinning in a dance, or on a skateboard in a half-pipe, or when trying to carry a ball through a swirl of opposing tacklers… etc. etc. etc.).

I will argue, in my second post, that the ethnographic study of different regimens for training balance and the ethnological project of comparing techniques of balance, allows us to better see an enormous variation in the way that this ‘sensory system’ engages the world and functions. A neuroanthropological and cross-cultural study of equilibrium suggests that the ability to stay upright is as varied as the demands humans make upon their balance systems. Training techniques lead humans to reconfigure their ways of finding and maintaining balance, the skill restructuring not just the ‘cultural information’ that they have, but the way that they perceive, the responses that they have (even without consciously reacting), and their physical ability to meet the demands of different balancing techniques.

But I’ll save that for the discussion of standing on one’s hands (in capoeira and in other physical disciplines) in Part 2 of this post.


Barrett, H. Clark, and Robert Kurzban.
2006. Modularity in cognition: Framing the debate. Psychological Review 113: 628-647. (pdf version available here.)

Fodor, Jerry.
1983. Modularity of Mind: An Essay on Faculty Psychology. Cambridge, Mass.: MIT Press.
1998. In Critical Condition: Polemical Essays on Cognitive Science and the Philosophy of Mind. Cambridge, Mass.: MIT Press.
2000. The Mind Doesn’t Work That Way: The Scope and Limits of Computational Psychology. Cambridge, MA: MIT Press.

Gibson, James J.
1979. The Ecological Approach to Visual Perception. Boston: Houghton Mifflin Company.

Hermer, Linda, and Elizabeth Spelke.
1996. Modularity and development: The case of spatial reorientation. Cognition 61(3):195-232.  (Abstract)

Karmiloff-Smith, Annette.
1992. Beyond Modularity: A Developmental Perspective on Cognitive Science. Cambridge, Mass.: MIT Press.

McGinn, Colin.
1989. Can We Solve the Mind-Body Problem? Mind 98 (391):349-366.

Uttal, William R.
2003. The New Phrenology: The Limits of Localizing Cognitive Processes in the Brain. Cambridge, Mass.: MIT Press.

10 thoughts on “Equilibrium, modularity, and training the brain-body

  1. In reading your piece, swimming came to mind as another way to think about balance. As a long-time competitive swimmer and coach/teacher, I think one of most underappreciated parts of swimming is the exquisite balance it takes. Take backstroke–without being able to relax and roll your torso from side to side, you’ll never be a strong backstroker because of the difficulty of getting a good “grip” of the water while maximizing the strength of your upper body on your hand and forarm. So balance isn’t even always about staying upright!

    I also appreciated your use of Gibson’s ecological psychology, which has much to offer neuroanthropology. A book I particularly like is Edward Reed’s Encountering the World: Toward An Ecological Psychology. Here’s a little snippet that relates to this post: “According to the present approach, actions are an animal’s modes of changing its relationship to its environment. Actions involve the detecting, obtaining, and utilization of affordances. The components of actions are not neural or muscular events, but are themselves processes of regulation, which I have termed postures and movements, indicating regulations that maintain and transform the animal’s relation to its environment, respectively. Traditional theories of action focus almost exclusively on questions having to do with the ordering and arranging of responses. The present approach implies that explanations of action should detail the various control processes involved in the interlocking movements and postures to achieve the desired functional effects (93).”

    Balance as a process of regulation seems to me like it fits a lot of what you are discussing, rather than the built-in module approach.

    Finally, I was also struck by Ekman’s work on emotions, in particular how Griffiths explores that in his book, What Emotions Are. The sort of universal emotional features that Ekman discovered seem precisely that, features that are relatively stereotypical and automatic, but then can vary in inputs, sequences, elaborations, and so forth. In reading your piece, I was struck how the brain/body issue is much like language, where it is quite patterned but that any particular piece of language is fairly unique. It’s our ability to combine, to sequence, to shift and adapt that is so impressive–thinking back now to your AAA presentation on human evolution and motor skills. But how about making a direct parallel? Something like the language of the body, where balance would be one basic pattern?

  2. Although it’s off the topic of balance (which is actually of great interest to me since my daughter is doing a high-school biology research project studying the balancing abilities of students with a range of athletic experiences and backgrounds!) — my first thought on reading the above comment was what its implications might be for understanding various tic disorders. I don’t know anything about ecological psychology — does it address movements that, like tics in Touretters, are neither entirely voluntary or involuntary?

  3. I’m no expert on ecological psychology, so I am not sure. You might try using Google Scholar to search more extensively. I did just a little bit, and nothing obvious popped out. But you might look more closely at the contents of the journal Ecological Psychology, and also these two books came up: Heft, Ecological Psychology in Context; Piek, Motor Behavior and Human Skill. I think it’s a great idea, so I look forward to hearing on the ecological approach to tic disorders in the near future! I am sure the overall approach will definitely have relevance, as one of ecological psychology’s strength is to get us beyond the volunary/involuntary dichotomy.

  4. Clare, I don’t know if ecopsycholgy or ecological psychology would have too much to say about tic disorders. It’s a way of thinking about psychological processes in natural settings, reacting against the over-simplification of perception, cognition, and other processes in rarefied laboratory settings.

    However, I think that some of the other material on neural plasticity would have a lot to say about how certain patterns of activity might become extremely difficult to change. In particular, I’d recommend The Mind and the Brain by Jeffrey Schwartz and Sharon Begley, which has some great stuff on Schwartz’s work with obsessive-compulsive disorder and the attempt to alter some terribly involuntary behaviours.

    In addition, recent books by Norman Doidge, The Brain that Changes Itself, and by Sharon Begley, Train Your Mind, Change Your Brain: How a New Science Reveals Our Extraordinary Potential to Transform Ourselves, might be relevant. One of the podcasts I posted on earlier has an interview with Doidge, a neuroscientist who also works with psychiatry, and he talks specifically about his work on stroke recovery and the difficulty (but possibility) of retraining deeply ingrained mental patterns that are rooted in organic configurations of the brain.

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