UPGRADE: Vol. VIII, Issue no. 2, April 2007 Information Technologies for Visually Impaired People

Monograph: Information Technologies for Visually Impaired People

Presentation
Introduction to Assistive Technology for the Blind [PDF: 6 pages, 393 KB]
Jaime López-Krahe - Guest Editor

The two fundamental problems facing blind people are the difficulty of knowing where they are and getting about, and the impossibility of having direct access to information, whether in written or in electronic form.

The evolution of assistive technologies for the blind saw a boom at the end of the last century, opening the doors to exciting new prospects for the present day.

Several articles of this monograph look at the current situation and the research outlook for these issues. In this introduction we will take a historical look at the evolution of assistive technology for the blind from the 18th century to the end of the millennium in the hope that it will help readers have a better understanding of this monograph.

According to the World Health Organization (WHO), blindness is a visual acuity of 20/400 or 0.05% in the better eye and with the best possible correction. The problem of helping the blind to integrate in everyday life has been addressed in some way or another since time immemorial. But where once only the most basic form of aid or merely compassion was offered, now a more autonomous concept of life for the visually impaired is pursued.

The greatest problems facing the blind to acquire this autonomy and their solutions fall into two main categories:

The possibility of getting around independently; in other words, mobility and navigation aids.
Access to written information and the social memory. This includes accessibility to digital information on computers by means of specialized digital interfaces.

1 Mobility Aids

The White Cane

Apart from those natural human aids (or rather guides) popularized in Spain by the fictional character Lazarillo, the first technical and intuitive aid is the simple stick. It allows the user to explore the cone of space within its reach although it cannot detect obstacles above ground level (overhanging or projecting objects, etc.) while hazards caused by level changes (stairs, holes in the ground) are only detectable if they are specifically explored. This "device" dates back a fair way as we can see in Bruegel the Elder’s dynamic and almost cinematographic painting "Parable of the blind leading the blind" (see Figure 1) in which we see a number of blind people guiding one another, with the leading ones falling over and bringing the ones behind down with them.

Figure 1: Parable of the blind leading the blind. 1568: P Bruegel the Elder, Pinacoteca di Capodimonte,
Naples, Tempera on canvas 86 x 154 cm.

After the catastrophe of the First World War the number of blind people grew considerably and the white cane came to be an instrument with a dual function: firstly it was to help blind people get around more easily and secondly to let the people around them know that the person using the white cane was visually impaired. This invention has been attributed to George A. Bonham of the Peoria Lions Club, Illinois, USA in 1930 and its use rapidly became widespread. The proper use of the white cane, and in particular of the long cane, requires special training by mobility instructors to optimize its usefulness.

The Guide Dog
The use of animals as mobility aids is relatively recent. By way of an anecdote, reproduced below is a photograph, probably from the late 19th century, showing a blind man being led by two hens (see Figure 2); the information conveyed by the photo is minimal and we can only assume that the level of training that a pair of hens can attain is also minimal to say the least. The first attempts to train guide dogs apparently occurred in Austria in the late 18th century according to references by Leopold Chimani who in 1827 mentions the case of Joseph Resinguer who had trained dogs for his own use. Later the rigid harness (Johann Wilhelm Klein, 1819) appeared but its use was ignored for practically a century. We had to wait for the consequences of the Second World War before the appearance of dog training establishments in a number of countries, often as a consequence of individual initiatives (Gerhard Stalling in Germany, Paul Corteville in France and later in Spain). We should also mention here the efforts of the Lions Club which has encouraged the development of this mobility and safety aid in many countries for people with visual impairment, including of course the ONCE.

Electronic Mobility Aid Devices
Late in the 20th century electronic mobility aids began to appear based on interferometer systems [1]. The first technologies used were based on the emission and reception of infrared rays which allowed obstacles to be detected by reflection up to a distance of 3 to 4 metres (Tom Pouce, Teletact)[2](see Figure 3). Later laser technology devices were used allowing a greater range and better processing of the information. These devices may take the form of canes or glasses which interface with the user in one of two ways; by touch or by sound. A tactile module enables the user to obtain information about obstacles. Acoustic systems provide information by means of tonal differences (higher or lower frequency) depending on the location of the obstacle and varying loudness to inform users about how far away the obstacle is. One of the difficulties preventing these devices from being more widely adopted is the need for specialized training in their use. The use of satellite positioning (GPS) and orientation devices open up further perspectives, although there are still some unresolved problems since in built-up areas the presence of buildings can interfere with satellite signals, especially on pavements. These devices can also be linked to mobile telephones capable of transmitting images, which enables users to summon remote human aid.

Blind Man Led by two Hens

Figure 2: Blind Man Led by Two Hens. Figure 3: Teletact.

2 Information Access Systems

Direct Transduction
Direct transduction devices convert visual information into information that is accessible to the blind. They do not use intelligent processing systems, but depend simply on energy transformation. This technology is often referred to as sensory substitution.

Tactile Stimulation
The first intuitive was in this sense to convert visual information directly into tactile stimulation, thereby respecting the two dimensions of shapes. The sense of touch is made up of nerve endings that can detect various sensations (cold, heat, pressure, etc.). It is important to know the exact nature of these nerve endings so as to be able to optimize their stimulation. One important feature is their spatial distribution frequency, especially of pressure sensitive receptors. In 1 cm2 the fingertip there may as many pressure receptors as in 200 cm2 of any other part of the body. Another important feature is that tactile sensory cells act on an On/Off basis, emitting an action potential when they are stimulated and also when they cease to be stimulated (for example, they "notice" when you put on a pair of glasses or a hat, and when you take them off, but not while you are wearing them). For this reason stimulation must be effected by prompting an exploration with movements or by making the stimulators vibrate. Around 1880 Camile Grim presented his "Anoculoscope", a prototype of 64 (8x8) light sensitive selenium cells which used electromagnets to activate an identical number of stimulating tactile pins according to the light that fell on matrix of cells[3]. Later other experiments focused on stimulation of the user’s back or tummy as can be seen in Figure 4 [4]. In the seventies another device appeared; the Optacon (see Figure 5), developed by Telesensory Corp. This was a device comprising a camera with 6x24 receptors connected to a screen with an identical number of vibrating pins that allowed the user to feel the shape by stimulating a finger. It was successfully marketed until the turn of the century. It enabled users to access documents, for example, after a basic training course, although reading speed remained slow and the process was tiring. A miniaturized camera was located on two rollers to make it easy to move along the line and it was equipped with a zoom and an adjustable tactile screen (frequency and intensity of vibration, inverse stimulation, etc.). Some research going on today in the field of visio-tactile sensory substitution is focusing on stimulating the underside of the tongue[5].

Acoustic stimulation
Another possibility of stimulation, although of a more abstract nature, is acoustic stimulation . In this case the idea is to transmit bi-dimensional information via a one dimensional channel such as hearing. However, by analyzing the frequency of such signals we can achieve a pseudo two dimensional encoding. The first research into this type of sensory substitution is attributed to Fournier d’Albe [6], who invented and perfected [7] the "Optophone" for which reading speeds of up to 60 words a minute were claimed [8] (although such a claim may be optimistic). Later other devices based on this principle were marketed, such as the "Visotoner" or its subsequent, more developed version, the "Stereotoner". It worked by means of a camera that projected an image onto an array of photo-receptors, each of which was associated with a rising or falling frequency depending on the position of the image. By passing the camera over a line of text a user would hear sounds representing the shape of each letter; for example the letter "v" would be represented by a tone that started high, then fell, and then rose again. Mauch Labs. Inc. ceased to manufacture these devices in 1977.

Transmission of Information by Dorsal or Ventral Stimulation

Figure 4: Transmission of Information by Dorsal Figure 5: Use of the Optacon.
or Ventral Stimulation.

Access to Written Information

Braille
The most commonly used method of reading for the blind is braille, invented in 1827 by Louis Braille in France when he was just 18 years old. It consists of a binary information system using a cell of six raised dots (2x3) which is well adapted to tactile exploration. A well trained blind person can achieve reading speeds akin to those of sighted people. The main drawbacks to the system was the space it occupied, its difficulty to learn, and the cost of producing texts.
It was an indirect system of access to the written word insofar as it required someone else to manually transcribe the text (although a number of copies could be made at the same time by putting two or three sheets in at the same time and pressing harder). In order to make reading faster and save space, some countries developed a kind of shorthand braille. There are specific coding systems to transcribe music scores or mathematical texts, which need to overcome the problem caused by the fact that braille is a linear system and music and maths require multi-dimensional information to be represented (matrices, fractions, five line staves). This information is represented by a system of operators and parentheses. Reproduction difficulties became a thing of the past with the appearance of the braille printer and the thermoformer – a kind of embossing photocopier.

The First Refreshable Braille Devices
In the mid seventies O. Tretiakoff invented an electronic system of refreshable braille on a 12 character display. By combining this display with a and audio cassette machine and a 6-key braille keyboard he produced an innovative device: the Digicassette. The braille was recorded on a cassette and could be read on the 12 character braille display (which was later increased to 20). This system made copying easy and solved the problem of the sheer volume to be stored. Later another US company came up with another, similar system, the VersaBraille (see Figure 6), which was equipped with a serial interface that allowed it to be connected to a computer. The early cassette based recording systems of Digicassette and VersaBraille were later upgraded to floppy disk. These computer connectable refreshable braille displays represented a major step towards Internet accessible systems.

Generation of Interface Devices
Until relatively recently the quality of speech synthesis was too poor to be used in assistive technology for the blind. Today that problem no longer exists and an ever increasing number of blind people are turning to this solution, which is not incompatible with Braille and, while it falls short in some areas, has some other very interesting advantages such as ease of access, ease of indexing, and the possibility of increasing reading speed. Today speech synthesis is a cheap and simple way of electronically accessing any text document. The refreshable braille systems used in Digicassette and VersaBraille paved the way for modern day devices employed as a means of accessing computerized systems directly via a braille interface (see Figure 7). Today practically all printed information is transmitted through electronic media which, once legal and administrative problems have been overcome, allows direct access either by speech synthesis or by braille.
This means that we have to take the needs of blind people into consideration when generating Web documents or pages. We need to take into account and respect W3C-WAI (Web Accessibility Initiative) recommendations to ensure that Web sites are accessible to everyone. A lack of awareness of these basic rules often prevents access to this type of information. Webmasters need to be aware of these initiatives and learn how to provide simple options for visually impaired people (contrast inversion, page amplification, etc.) It is more a problem of culture and unawareness than a lack of willingness so any information in this regard can only be welcome.

Figure 6: VersaBraille. Figure 7: Refreshable Braille Interface Device.

Advances in Form Recognition
The first reading machine based on intelligent character recognition was designed by Kurzweil who in the early eighties marketed a device that enabled blind people to access printed text automatically. It was a machine (like a large photocopier) which processed an image and outputted a speech synthesis in English. It was specifically designed for the blind and its high price meant that its use was mainly limited to specialized centres and libraries. More recently, thanks to the widespread use of office applications, the cost of hardware and software has come down so much (computer, scanner, OCR package, speech synthesis or braille line) that it is now a reasonable option in terms of achieving direct access to the printed word. Moving towards the present day, we should look at such inventions as the KNFB reader, also invented by Kurzweil, which is the first portable automatic reading device to read printed texts. It is based on a combination of numerical photography, PDA, and speech synthesis with a considerable memory. The device detects the edges of the document, indicates when the photo can be taken, and in a matter of seconds the text can be heard. These small computers equipped with cameras can also be used to identify everyday objects; cans of drink, caned foods, medicines, etc.

Low Vision
The definition of blindness that we saw earlier involves the total absence of vision, but in many cases the use of residual vision is also an option, provided that the right equipment is available. From conventional magnifying glasses to electronic magnifiers sometimes linked to a computer and character recognition systems, there are solutions available to help those with low vision access information. Depending on the nature of the residual vision, such devices can allow users to alter the presentation, colour, size, etc. of the text they wish to read.

3 Conclusion
The purpose of this brief historical overview is to introduce the subject of this edition and give readers a better understanding of the assistive products available to help the blind and partially sighted integrate into the information society and achieve autonomy.

In the following articles readers will be able to see the current trends, the state of the art, the direction that research is taking, and the developments we can expect in the matter of assistive technology.

Two clear trends can be identified:

A specific development, the need for which arises at a specific moment in time, such as braille displays.
The use of general purpose technologies that can be developed as technology advances.

If it is impossible to avoid using special interfaces, it would seem logical to ensure that such devices are produced in such a way as to be integratable with conventional technology by using standard connection methods and protocols. Otherwise the result will be products that are too costly, hard to maintain, and with a tendency to become quickly obsolete, to the consequent frustration of their users. Thus, the development of general purpose OCR, with its falling cost and increasing reliability, is causing information access devices of a more special purpose nature to gradually disappear. Digicasette, VersaBraille, Optacon, Stereotoner and other such devices have given way to an ever changing information technology and an (accessible?) Internet with specially adapted but minimalist interfaces that integrate perfectly and make use of existing general purpose systems.

Translation by Steve Turpin

References

[1] C. Jacquet, Y. Bellik, Y. Bourda. Electronic Locomotion Aids for the Blind: Towards More Assistive Systems. In Studies in Computational Intelligence, Intelligent Paradigms in Assistive and Preventive Healthcare, ISBN: 3-540-31762-7, N. Ichalkaranje, A. Ichalkaranje, L.C. Jain (Eds.), Springer-Verlag, Vol. 19, 2006, pp. 133-163.
[2] R. Farcy, R. Damaschini, R. Legras, R. Leroux, Y. Bellik, C. Jacquet, J. Greene, P. Pardo, L. Agro, J.M. Murienne et A. Zoghaghi. Perception de l’espace et locomotion des non-voyants par profilométrie laser: aides électroniques à la locomotion, J3eA - Vol. 3, Hors-Série 1 - 5 (2004). DOI: 10.1051/bib-j3ea: 2004605.
[3] Gallois. Anoculoscope. Bulletin Le Valentin Haüy, Paris, Octobre 1883.
[4] P. Bach-y-Rita. A tactile vision substitution system based on sensory plastic, in Visual Prosthesis. Ac. Press, 1971.
[5] P. Bach-y-Rita, S.W. Kercel. Sensory substitution and the human-machine interface. TRENDS in Cognitive Sciences, Vol. 7, No. 12, December 2003.
[6] E.E. Fournier d’Albe, The Type Reading Optophone. Nature, Vol. 94, pp 4, London, September 1914.
[7] E.E. Fournier d’Albe. The Optophone: an instrument for reading by ear. Nature, Vol. 105, London, May 1920, pp. 295-296.
[8] J.C. Nye, P. Bliss. Sensory Aids for the blind:a challenging problem with lessons for the future. Proc. of the IEEE. Vol. 58, No. 12, December 1970.

Last updated on September 26th, 2007

by the Editorial Team of Upgrade