In many occasions, the characteristics of haptic functioning in totally blind persons and in blindfolded sighted ones have been compared in the preceding chapters. These studies had mainly a theoretical interest allowing, for example, the evaluation of the role of visual representations and of haptic training in the functioning of this modality. Other available works review extensively the state of our knowledge concerning the cognitive consequences of early blindness (for example, Hatwell 2003; Heller 2000; Warren 1994). The last section of this book considers some particular aspects of the visual impairment per se. Starting from what we know now about the possibilities and limits of touch, it addresses the practical consequences of blindness or, more exactly, the techniques and devices that have been developed to compensate, as much as possible, for the perceptual handicap generated by permanent visual deprivation.
Obviously, a remediation technique was most acutely needed in the area of reading and writing. During centuries, blind children could not have systematically access to instruction and written culture. Their schooling became much easier when Louis Braille, who was himself a blind pupil attending the Royal Institute for the Blind in Paris (now Institut National des Jeunes Aveugles), proposed in 1829 the raised dot embossed alphabet known all around the world as braille alphabet (cf. Chapter 14, Figure 14.1). This alphabet is remarkably well adapted to the sensory capacities of the internal face of the last phalange of the index finger and it may express punctuation, mathematical signs, musical notation, etc. It has further been adopted in all languages for the transcription of texts for the blind. More recently, the number of points in the braille cell (the unit which defines a letter) has been increased from six to eight so that computer language could be written in braille.
However, the characteristics of the braille alphabet raise particular problems in children and adults when they learn and use it. In the last decades, a number of studies have been conducted on the processes of braille learning and they have concentrated on different problems such as perceptual aspects (sensory discrimination, efficiency of the right and left hands, cooperation between the two hands during bimanual reading), spatial aspects (braille letters are not redundant and can be identified only through the spatial localization of the dots composing them. This is difficult for the young child because no spatial frame of reference is available), phonological and semantic aspects, etc. An original and complete presentation of these studies could be found in Millar (1997). Another trend of research presented here by Tobin, Greaney and Hill (Chapter 14) is centered on the problems of teaching braille to young children and to adults who have recently lost their sight. The introduction of abbreviations and contractions (in Level 2 braille) gains much space and speeds up reading, but it raises multiple difficulties in pupils and teachers. Experimentally tested simplifications are proposed by Tobin et al. who nevertheless stress the users' strong resistance to any modification of the graphic code they are accustomed to.
Whatever it may be, books in braille have long been available to blind people. But, until recently, they had no illustrations, first because there was no technology able to make pictures in relief at a reasonable price, but mainly because it seemed obvious that bidimensional drawings were very difficult to understand by early blind people who have no projective space. The situation has changed over 30 years. There are machines today which can emboss pictures in raised lines or in thermoformed relief allowing the addition of texture to their surfaces. These machines allow now the publication of city maps helping blind people to find their way about their town, their locality or their school, or pictures representing objects, biological and geometrical diagrams, etc. Some observations have revealed that the blind, and even the congenitally blind, are capable of producing pictures which have certain rules of representation in common with the picture production of sighted people (Kennedy 1993,2000). The use of graphic supports in teaching the blind is thus becoming widespread. In Chapter 15, Hatwell and Martinez-Sarocchi analyze the problems posed by these supports. The study continues with a discussion of the procedures used by publishers of art books and museum curators to make works of art more accessible to the blind.
Another handicap resulting from blindness is the reduction in autonomy with regard to personal mobility, which is a direct consequence of the fact that touch is a sense depending on contact. Only the immediate environment is perceptible, thus making orientation and walking in open spaces (the locality or a town) difficult and dangerous. Devices have thus been developed to transform luminous stimulations in the environment to tactile stimulations perceptible to the blind. The best known of these sensory prosthetic devices is the Tactile-Vision-Substitution-System (TVSS) developed in the 1960's and 1970's by Bach y Rita (1972). The use of this system by early blind people in laboratory research has improved our knowledge of tactile (and, paradoxically, also visual) functioning. Nevertheless, despite many refinements and minia-turizations, it has had little practical success among the blind. In Chapter 16, Lenay, Gapenne, Hanneton, Marque and Genouelle analyze and discuss the psychological processes underlying the use of this device. They explain that the TVSS does not produce a true sensory substitution, but constitutes rather the addition of a particular form of perception.
The final chapter is concerned with the adaptation to the visually impaired people of the new technologies of information so widespread today. While it is fairly easy to transform the texts appearing on a standard computer screen into embossed braille writing, the situation has become more difficult for the blind when icons and graphics have partly replaced the written codes, because these icons are very difficult to distinguish by touch. In Chapter 17, Burger examines the techniques used to adapt the new technologies to visual deficiency and presents the problems arising from this adaptation as well as the solutions proposed.
This overview of the studies contained in the present book shows that, while retaining the principal aim of studying the psychological processes at work in the cognitive functioning of touch, our attention has also been drawn to the practical consequences that the characteristics of this modality can have, especially in blindness, and to the means of taking these consequences into account. Of course, the book is not exhaustive and many aspects of the cognitive particularities of the tactile functioning of the sighted and the blind could not be examined in its limited framework. We hope however that it may interest not only students and researchers in cognitive psychology, but also practitioners (teachers, psychomotricians, education assistants, etc.) confronted with the problems of visual deficiency. This book may also be useful to the ergonomists who design sensory prostheses and adapt new technologies for the blind, and to the roboticians who need to know the role of tactile reafferences in movement control. In short, this work is for all those who seek to understand how and why "knowing by touching" is possible.
Was this article helpful?