Tactile graphics and the functional reorganization of imagesGiuseppe Di Grande Published the 03/25/2021 16:00
The blind child acts and interacts in a small portion of space around him that he learns to know from a tactile point of view. When creating tactile graphs, starting from visual images or new projects, it is necessary to take into account that, while the sighted child has a global and overall perception and then, later, detects the detail, the detail, the blind child does exactly the opposite: first he detects the detail through haptic exploration and then builds the whole, the sum of the details explored.
No other sense offers globality in the perception offered by the eye. Visual deprivation involves a significant functional reorganization that is expressed through the strategic use of other sensory channels (smell, touch, hearing). This compensatory process is not a spontaneous and biological ability, but is an intentional process induced by the presence of a stimulating educational and living context. In the first 5 years of life): blind children, if appropriately stimulated, learn and reproduce spatial attributes such as proximity, separation, continuity, discontinuity, containment, inclusion of one object in another. Between ages 5 and 10): include direction, curved and straight lines, length and distance.
Just as motor skills enable exploration of the environment and knowledge of reality, contextually the same concepts of reality can be reproduced symbolically using tactile graphics. Children are able to perceive an object in relation to other objects and points of view, but they develop knowledge of projective geometry that progresses from this stage forward. Children use touch intensively to access spatial and physical knowledge of their surroundings. This intensification does not change sensory levels, but it directs attention toward certain clues and enhances exploration procedures. In addition to tactile exploration of the environment, appropriately designed tactile patterns can expand opportunities to explore the environment, interact with peers, or communicate with others.
The Tactile System is what receives and transmits information from sensory receptors located in our skin. It is through the Tactile System that children receive information about the world around them. The ability to process tactile information allows him or her to feel safe and form bonds with others. The most advanced somatic experience consists of active manual exploration of the environment. The tactile system has not only a passive role (receiving and processing stimuli), but is an integral part of the chain of nervous mechanisms that control muscle contractions, movements, and, in general, tactile exploration.
In order for the blind child to have the correct skills to perceive graphics and symbols by touch, it is essential that education is oriented to the communication of other information useful for the knowledge of everything around him. To achieve this goal, tactile graphics and language are the most functional compensatory tools. Through words and tactile graphics, it is possible to assign a name and a face to aspects and things of everyday life that the blind child would not be able to experience independently. The absence of direct visual experience makes the construction of the world of objects much more difficult. Therefore, the child has difficulties related to abstraction and understanding of concepts that cannot be experienced. Due to the lack of an imaginative background equivalent to that of sighted children, he comes later to the understanding of certain concepts. He soon becomes aware of the impossibility of touching everything. The child cannot, with as much autonomy as the sighted child, recover this knowledge if deprived of an appropriate and in-depth education to tactility through compensatory tools such as models and charts. Moreover, it is useful to integrate tactile exploration with an adequate verbal support, since combining appropriate terminology with concrete evidence means affecting learning and favoring the memorization of concepts.
The mental images of blind children have globally the same functional properties as those of sighted children, even if their mental manipulation is slower, more laborious and sometimes less performing than those of visually dominant images, especially when a large amount of spatial information or typically visual data must be processed.
When making a tactile drawing, it is also necessary to evaluate the degree of legibility of the relief, in compliance with tolerable tactile thresholds shared in the world of haptic perception and visual impairment. The exploration of tactile images takes place in two phases: a reconnaissance of the entire image, which aims to build a general scheme; an analytical exploration that succeeds in capturing the details. even if touch allows the knowledge of almost all the properties of objects such as shape, size, spatial location, stiffness, weight, temperature and so on, and a careful tactile exploration allows to recreate in the mind the correct image, we must always keep in mind that touch has a reduced discrimination capacity: it is unable to perceive very fine details: lines or points too close to each other, segments too short and so on. This condition requires drawing in a simpler and more essential way. It is unthinkable to convey through a relief drawing the same amount of information that is normally conveyed through a visual representation of the same size. A relief drawing that is too rich in detail only ends up confusing and disorienting. In addition, the sense of touch cannot directly perceive variations in light and color. Shading of any kind should be eliminated from the relief drawing, as well as any unnecessary chromatic reference. Therefore, in order to simplify the images, a very substantial amount of information should be eliminated; however, avoid drawings that are too vague and generic.
One approach might be to carefully define the overall shape of the image, making the outer contour line of the dominant object you want to represent as clear as possible. In addition, it is necessary to emphasize the unique details, those that unequivocally mark the specificity of the object you want to represent. It is always necessary to remember that the blind child first detects the detail and then builds the whole. Simplifying the image in order to avoid redundant and confusing information also means completely erasing the background and all the information it contains.
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