Communication about vision is frequently misunderstood because vision is misunderstood. Vision is not passive or static. The reason that the role of vision in reading problems, for example, is overlooked in the inadequate and misleading definition of vision as 20/20. Accurate eye movements are critical for vision to be effective. The primary function of vision is to guide, predict, and monitor movement. Vision cannot be isolated from movement. Vision and movement use more of the brain than does resolving details (visual acuity) and recognizing what they are (visual memory).
A patient may have a specific diagnosis such as convergence insufficiency, but pieces of the visual process cannot be treated in isolation. The visual system is integrative and must be rehabilitated with respect to how the visual system developments. These principles are supported by the following research….
There is no perception of space or movement, no vertigo or loss of balance, no caress given or received, no sound heard or uttered, no gesture of capture or grasping that is not accompanied by emotion or induced by it. p. 7
Merleau-Ponty put it very well: “Vision is the brain’s way of touching.” p. 11
Indeed, a true physiology of perception must abandon the idea of splitting up sensory functions and instead approach them by way of their multisensory character. p. 57
Perception of distance is the result of visual messages and signals from the convergence of the two eyes. This action is used to gain information about the world. p. 76
Tactile perception is not only connected with vision, it is also influenced by the active character of visual attention. p. 87
Natural movement is a source of pleasure and pleasure is a necessary element of perception and cognition. p. 137
Oculomotor pursuit is essentially predictive. p. 151
Perception is active exploration; it is a question put to the world, a wager, pre-selection – it is also capture. Consider gaze. Visual perception is possible only by actively exploring the environment through gazing, through the changes in perspective enabled by movements of the eyes that I call stationary locomotion. Each gaze cast constitutes capture, especially if the object of regard is in motion. This capture is anticipatory, predictive. For example, try to read this page aloud. You will be struck by the coexistence of two coordinated actions: your voice, which articulates the text, and a silent reading preceding it. Bernstein said that we have two texts in our heads: the one we read aloud and the one that we look at in advance to prepare our reading. This phenomenon is well knows to musicians, who are always reading the score one or two measures ahead. According to Bernstein, planning a motor action, however it is encoded by the nervous system, necessarily involves recognizing patterns of what will be but do not yet exist. Planning requires exploration of the future. Just as the brain constructs an image of the real external world, it must be capable of planning in advance. p. 165
Although we may be unaware of our eyes moving as we perceive an object such as a face, visual perception is dependent on many eye movements each second. Our perception is an illusion constructed by the brain as if it was seen all at once. p. 192
The brain is like a spirited horse that inhibition handles much the way a horseman handles his reins. Refinement of sensorimotor function is dependent on subtle inhibitory mechanisms which enable new motor competencies. Neural inhibition is one of the basic mechanisms of the production of movement and its flexibility, and probably the main mechanism of sensorimotor training. It is also the source of perceptual mechanisms of filtering. p. 193
Motor equivalence refers to a simple and remarkable property of the brain that enables the same movement to be made using very different effectors. For example, I can write the letter A with my hand, or my foot, or my mouth. p. 227 An important application of this is a better way to teach handwriting.