Brock’s Brilliance Revisited

Leuven is a lovely college town in Flanders  where history, culture, architecture, gastronomy and modern science merge to form the ideal setting for a workshop on neuropsychology.  Were he alive today, Dr. Fred Brock, optometrist extraordinaire, would have devoured the topics presented there. The name Brock is well known in our field primarily because of his contributions to String Theory.  Not the same string theory that quantum physics occupies itself with, but the concepts behind an elegant vision therapy tool that serves to elaborate visual space.

The thing about the Brock String when we first demonstrate it to patients is that it looks much too simplistic to be a powerful vision therapy tool.  But in the right hands, and with the proper instructional guidelines, it becomes a magnificent tool for exploring one’s visual space world.  Here’s the basic idea.  Tie one end of a rope to a doorknob and hold the opposite end to the bridge of your nose.  Actually, you don’t need me to explain it to you – there’s a marvelous online video that was done that will walk you through it.

The way the video reviews the procedure is the way we routinely instructed patients, largely about the string guiding you on where your eyes are meeting in space compared to where you’re aiming them.  We also knew that patients had to be at a certain cognitive level, developmentally, before they were able to deal with it.  After all, the normal binocular perception of what we call physiological diplopia is a type of virtual reality experience.  Even more, it relies on divided attention to be able to select one bead or point in space and simultaneously be aware of what’s happening in the region in front or behind of that point.  This task also requires that the patient attends to the central field while simultaneously being aware of periphery in 3-D space.

But wait, there’s more!  Neuropsychology speaks of three regions of space related to your body:  personal – in your immediate surround; peripersonal – within reaching distance; and extrapersonal – beyond that point.  So with the front bead near your nose, the second bead within arm’s length, and the third bead at the far end, we can depict this as the  Brock Graphic Space.

There are all kinds of exciting implications to this.  One is that these spatial areas are coded differently by different parts of the brain.  Another is that the spatial codes mapping near space and far space are intimately tied in to the accommodative and vergence systems.  The notion of personal space may be related directly to the Skeffingtonian   “centering” of one’s body in a social setting, a key concept lacking in many children who are on the autistic spectrum.  This has further applications to the Brock String regarding the difference in how space is partitioned when one is using, for example a dowel stick to help localize where the middle or far bead is in space relative to the patient’s body.

Now consider this:  would the effect of using a dowel stick to localize a point in space by touch be the same as using a laser pointer to localize that location in space?  Further, what if an individual were experiencing what is known as visual inattention or neglect after acquired brain injury.  Would it be possible to have neglect of one side of visual space selectively in near space but not in far space?  The answers to these questions reside in part in what took place in the lovely Belgian town of Leuven, during last weekend’s  Neuropsychology Workshop.

Only in part, because it takes a brilliant clinician like Fred Brock to illuminate how we modify these apparent adaptive oddities of visual space.  Add lenses, prisms, filters and movement to alter the appearance of the Brock String through the continuum of personal—peripersonal—extrapersonal visual space, and you build a powerful bridge between neuropsychology and optometric vision therapy.

– Leonard J. Press, O.D., FCOVD, FAAO

18 thoughts on “Brock’s Brilliance Revisited

  1. A wonderful article Len. Bravo. A great dedication to one of our leaders in vision therapy who led the way for so many of us. One the ways I use the Brock String is to guide the patient into their own inner areas of space. I do this by translating the outer experience through their eyes, to feeling the correlate space within. Then, they identify that each position of space correlates to particular emotional state. Inner space is like a spatial map of perceptual consciousness. In this way, the patient quickly learns what part of themselves they aremsuppressing when the get the feedback outside. In other words, the eyes become their best friend by the nature of this visual biofeedback system.

    • Thanks, RK. It has always intrigued me that our head and neck, including eyes and ears, are the only parts of our bodies that we can’t view directly other than through second order viewing via images of same. Hence the need for special representations of this region of body space, both internally and externally, that must be matched.

      How perceptual consciousness guides inner space, and matches that with outward space, is the crux of egocentric/allocentric literature. It is elusive, and I’m in the process of re-looking at some of your work, and trying to dovetail that with consciousness researches such as Damasio – whose new book on the subject is delightful.

  2. Hi—very interesting meeting, and certainly something all optometrists working in brain injury in the broadest sense should take note of. One of the speakers at the meeting was HO Karnath, who is both a neuropsychologist and neurologist—I love his work!

    BTW, Diana Ludlam and I have organized the speakers for this year’s NORA in April, 2011—Karnath will be speaking for 2 hours on more of his fascinating endeavors, and we will likely also have some small group discussions with him—we have arranged a line-up of great speakers.

  3. Drs Press, Ciufredda, Maples, great to see your comment on this subject.

    Read a lot of all of your individual work and was at the lectures way back with W.C. was in Flanders, as (then) chairman of the VT-Optometrists group in the Netherlands. Trained with drs Getman, Sanet, Harris.
    will read Domasio and would love to build an experience ‘ string’ with you on this subject.
    what can be arranged in the future to bring a NORA meeting digitally available to the world of optometry?

    cordiali saluti from the Netherlands
    Onno Rueck

  4. Hi Len

    I find that getting my patients to hold the string higher up on the nose, nearer the bridge. I find that training that way helps prepare them for using eccentric circles and lifesavers in the straight ahead position.
    Thanks for posting your thoughts.

    • Agreed, Robert. Another interesting feature of the Brock String is the ability to literally hinge the origin of the string close to the cyclopean projection. The only reason for not holding the rope so that it’s origin is literally between the eyes is a pragmatic one of blocking off the image of one eye with one’s hand. As with ECs and Life Savers, a great advantage of the Brock String is the ability to use it in various positions of gaze, a huge factor when there is non-comitant phoria or strabismus, working from the postiion of best fusion and gradually extending it. Most other binoucular arragements we have involves wearing anaglyphic or polaroid specs, which either create cancellation problems, or being cutoff by the periphery of the frame. With ECs or Life Savers one deals other affordances, such as optic flow of the background, as the circles are being moved. With Brock String (as with EC/LSs) we make a point, particularly when there are cyclovertical imbalances and/or visual-vestibular integration issues, to have the patient pivot the head in each of the three major axes (chin up/down; head tilt R/L; head rotated R/). Feeling and seeing the string hinged to one’s nose gives a greater anchor to making a good vestibular match with the induced visual angle of binocular rotation.

  5. A nice video production explaining the use of Brock string.

    My query is with regards to the term of “peripersonal” space as a separate category. I would have thought peripersonal and extrapersonal are the same. Is there any evidence to support the claim of separate brain areas for each? Both involve motor planning to explore being arm leg or oculomotor.

    • Thanks, Julius. Actually peripersonal and extrapersonal are quite different. Peripersonal by definition is space beyond the immediate body space, but within reach even, even when that reach is by extension, but not within a body part proper. The practical application is touch, and for VT most commonly would arise with a dowel stick used to localize position beyond arm’s length per se but within extension of peripersonal space via the dowel stick extension. Extrapersonal is defined as beyond reach, including beyond what is beyond touch by peripersonal extension.

      The gray area arises when one uses a laser pointer. There is no kinesthetic feedback as there is with a dowel stick, and it can be a visual-motor projection well beyond conventional peripersonal space, so function is more akin to visual judgement of extrapersonal space. This is all of intense interest in rehabilitation and parsing out alterations in visual space and how to modify them.

  6. It is great seeing this interest in the use of the Brock String and the varied theories behind the appreciation of visual space. My approach in guiding my patients through the steps has evolved into a very dynamic interactive process. Firstly, I recognised a deeper distinction between the eye, brain and visual processing. There is also the mind. (1) Even though respected scientists equate the brain and the mind as the same, my experience is different.(1) The mind is the human elaboration of the life experiences stored in the brain. It is the interaction of the person through their brain that directs and controls the eyes. In addition, the space represented by the perceived strings is a reflection of this intimate personal space of the person’s inner mapped world. As the patient reveals to me the suspensions and suppressions of their perceptions of the string, I have developed word descriptors to explore their personal perceptual map. It is seems that the person’s inner space is constructed from perceptual elements that make up a larger space which defines their perceived sense of consciousness itself. Suppressions further away are their way of dealing with the outside world, while the suppressions close to their nose reflect their stored mind’s view of themselves. I have mapped the different areas of space we use with the Brock String. For example for the outer right visual field I might say the word ego or will power. I wait to see their visual reaction or response. Through association, the person observes what happens to their perception of the string while considering these words. If the suppression is deepened, I guide them to generate a healthy view and they turn on this new perceptions through the eyes. It is not so simple, since each eye seems to hold a particular perceptual consciousness. I have suggested that this may be related to masculine and feminine perceptual qualities. (2) Interested in more?(2)

    (1) Kaplan, Roberto, Light, Lenses and the Mind – The Potent Medicine of Optometry, The journal of Optometric Development, Volume 22, number 44, Fall, 2002.
    (2) Kaplan, Robert-Michael, The Power Behind Your Eyes, Inner Traditions, 1994.

    • Thank you for sharing your thoughts further. What you are describing, and I recognize that you were one of the pioneers in this, is currently a very hot topic in neuropscyhology encompassing “embodied cognition”. Aside from exploring this further in order to merge some classical concepts with your approach to mind-body interactions, I have returned to reading Helmholtz’s original work on physiological optics. Later in life he immersed himself in the consciousness aspect of visual space, which he termed the psychic faculties of binocular space projection. How the inner maps of one’s consciousness project outward and loop back is, I realize, very heavy stuff.

  7. Hi Len,
    Thanks as always. Perhaps some of the periodic intermitant Strabismics who have turns and different sensory adaptations at different distances are, at the core, processing differently in peripersonal and extrapersonal space. The string therapy is a bridge in real space that we have to guide our patients across.

  8. ‘which he termed the psychic faculties of binocular space projection’

    Len, would you e so kind as to elaborate on this conclusion on Helmholtz’s writing?

    much obliged
    Onno Rueck

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