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Assistive Devices for People with Visual Impairments

J M Gill

Over the next two decades, there will be an increase in the number of people over retirement age, a decrease in the number of people paying income tax, and an increase in the expectation concerning quality of life by older people. All this has implications for the appropriate use of technology to assist people to live independently for longer.

Since over half of visually impaired persons in the UK live alone, they have to cope with cooking, housework, taking medication and personal care. In addition they may want to maintain their garden and join in social activities such as sports. A variety of ingenious devices have been developed to assist with specific activities.

Domestic appliances
In the past the controls on most domestic appliances (eg washing machines, cookers and central heating controllers) could be modified for a blind person by adding embossed markings to the control panel. However the change from electro-mechanical controls to dynamic visual displays has meant that other solutions must be found, and it has not been economically viable to modify each device individually to give speech output.

Packaging
Developments for the general public are not always to the advantage of visually impaired persons. For instance, the standardisation of packaging means that aerosol containers of oven cleaner and hairspray can feel the same. One small step was the introduction of an embossed triangle on packaging of dangerous substances.  A few items are specially designed to be easy to differentiate by touch to help blind persons; for instance the bank notes in the UK are of different sizes depending on denomination.

Food preparation
The essential aspect is for a blind cook to be well organised. There are a number of techniques, ways of doing things, such as for cutting and peeling vegetables. In addition devices, such as talking weighing scales, can help. However many problems remain. Opening tamper-proof packaging can be very difficult. Graphics and indicators on controls can be very difficult to see, especially if they are small or use low contrast colours.

Medicines
For many older people, taking medicines is part of everyday life. Often there are problems in differentiating tablets and in accurately measuring liquids. A number of devices have been developed but most are difficult to use by someone with poor manual dexterity or a hand tremor.  Labels are often in small print with poor visual contrast. It is somewhat surprising that the labels on eye drop bottles are often difficult to read despite the probability of the user having impaired vision.

Shopping
The increase in out-of-town supermarkets has resulted in the gradual demise of local shops. This change has been to the disadvantage of many visually impaired persons who benefited from the personal service the local shops could offer. In supermarkets it can be difficult to find the right products, and even harder to determine the price.  There have been a number of proposals for using the barcode to help visually impaired people sort their groceries at home. The barcode gives the product number so it would be necessary to have a databank to relate this number to the product name and label information. As yet the cost of providing such a service is too high, but this could change in the next few years.

Smart housing
The interconnection of devices in the home has been held back by the lack of a consensus on appropriate standards, but this may be partly resolved in the foreseeable future by such systems as Bluetooth. However the television set may become the central display for such a system, and therefore it is essential that allowance is made by the designers for people who have difficulty in reading the screen or understanding the process.

A simple smart house might give an audible warning of any windows left open when someone locks the front door from the outside. Also it could provide warnings about a cooker left on, show who is at the door and allow remote adjustment of heating, etc. In addition it is possible to connect the internal system to a telecommunications link to provide remote assistance or telemedicine.  The reason for the great interest in this area is the realisation of the economic necessity for as many people as possible to live independently for as long as possible. The cost of the technology involved in smart housing is modest when compared with the cost of residential care.

Television
Television is today's main medium for information and entertainment. Indirect controls are now the standard interface for most systems and these can be difficult to use by people with low vision.

Mobility and Orientation

The environment in which we live is becoming increasingly complex. Even journey across a city by bus requires a range of skills including:
• Being able to avoid obstacles on the pavement.
• To walk in the right direction.
• To safely cross the road.
• To know when you have reached a destination (eg found the correct bus stop).
• To know which is the right bus.
• To pay the correct fare.
• To find a vacant seat.
• To know when to alight from the bus.

These tasks may seem trivial, but for someone with no useful vision they are skills which have to be learnt. Even for someone with low vision, all these tasks are less easy than for someone with normal sight.

Electronic mobility aids
Over the last thirty years, engineers have devoted considerable resources to developing electronic systems to help a blind person avoid obstacles. The most common approach has been to use ultrasonics; as with radar, the range is obtained from the length of time it takes for a pulse to be reflected back to the transceiver. Other systems have used lasers or infra-red.   Many of the devices just provided information about the range of the nearest object; a 'picture' could be built up by moving the sensor from side to side. Other devices have attempted to give a more complete image of the environment but at the expense of providing an excessive amount of information to the blind user.

The main problems are not in designing the electronic circuitry for a satisfactory electronic mobility aid but in:

The capacities of the senses of hearing and touch are very small compared to that of the visual channel for a human. Therefore selecting and processing the information to make best use of the non-visual channels is not a simple task. The sensors in future devices are likely to involve more than one modality (eg both a video camera and an ultrasonic transceiver) in order to obtain the necessary data which can be processed to produce an accurate image of the immediate environment. However the research which has been done on the automatic processing of satellite pictures and the research on neural networks offer hope that significant advances could be made in the next few years.

Embossed maps
For a blind person, the problem of getting about is not just that of not walking into objects. One problem is that of knowing the layout of the environment; here, an embossed map can help. However embossed maps are not easy to produce or interpret since just embossing a sighted map seldom leads to an intelligible embossed map.

The problem of converting a sighted graphical representation to an embossed one can be illustrated by the problem of indicating direction. Visually it is often shown as an arrow on a line. An embossed arrow gives a sense of direction at only one point on the line and the symbol is unfamiliar to many blind persons. However a line sawtooth in cross-section has an indication of direction over the whole length of the line, and it is easy to associate the symbol with the meaning since the line is smooth in one direction and rough in the other.

Computer-aided design systems have been developed to speed up the process of producing embossed maps and diagrams. However there is still much work to be done on the design of the maps and on methods of tactual reading.

Orientation systems
Even with an embossed map and a mobility aid, it is still very easy for a blind person to get lost. A number of electronic orientation aids have been developed, but few have been widely used because of the cost of modifying the environment.  One type of system uses infra-red transmitters mounted at street corners; the infra-red signal is modulated so that a receiver, held by the blind person, gives out an audible message. These systems can also be used to indicate the status of traffic lights. Similar radio-based systems have been used in some countries, but the advent of Bluetooth is likely to dramatically reduce the cost of installing such systems.

A different concept is for the blind person to carry a tag similar to the ones used in shop security systems. Thus machines can detect the presence of a blind person within a few metres and modify their behaviour (eg give out a speech message). The tag or smart card can be pre-coded, which could indicate that the person would prefer messages in an alternative language.

Positioning systems
Satellite navigation systems, such as the Global Positioning System (GPS), can be used to determine one's position to a few metres. However this requires line-of-sight to three or four satellites, which means being outdoors and not close to tall buildings. This position is just given as latitude and longitude, so it needs to be integrated with a detailed digital map of the area.  Just such a system was successfully developed by the MoBIC project; this prototype system gave blind pedestrians their position within 2 metres, but only for 75% of the time. The problem was loss of line of sight to sufficient satellites or loss of the differential radio signal. However, it proved the technical feasibility and helped identify the problems in designing the man-machine interface for blind users.

An alternative method of finding one's position is possible from mobile telephony by determining the relative signal strengths at different base stations. With the next generation of mobile systems, this has been further developed so that sighted users can be provided with information related to their locality (eg the location of the nearest cash dispenser or Chinese restaurant). The advantage of the mobile telephony system is that it does not require line of sight to satellites, but the accuracy may not be as good as GPS. But, as always, the price charged to blind people for the equipment and using the service will be a significant factor in determining its takeup.

Access to Information

It is a myth that vision is a finite commodity and that using it means that it will fail sooner. When conventional spectacles give insufficient correction, low vision aids can be used. These devices include simple hand-held magnifiers, stand-mounted magnifiers, and spectacle-mounted and hand-held Telescopes. In general the higher the power of magnification the smaller the field of view and the shorter the working distance (ie the space between the aid and the material to be viewed).

Closed circuit television
Closed-circuit television systems offer the possibility for the individual to select the appropriate magnification combined with image enhancement (ie improved contrast) and image reversal (eg white print on a black background). There are also head-borne devices with automatic focussing which can be used at any distance, but the price of these devices is high.

Lighting
Lighting is probably the single most important factor in facilitating reading by older people. In general older people benefit from high levels of illumination, but the problem is to obtain these levels without the user suffering from glare. The illumination on a surface is inversely proportional to the square of the distance from the luminaire. Therefore bringing a reading lamp to a third the distance will give nine times as much light on the reading material. Many people benefit from simple solutions such as replacing a conventional bulb in a reading lamp with a spotlight bulb of the same wattage; this results in seven times as much illumination on the reading material.

Audio
One of the most useful aids for a blind person is a tape recorder since it requires few special skills to record or to listen to the material. However there are a number of problems such as controlling the speed of playback and indexing. If a tape recording is speeded up, the pitch goes up making it difficult to understand (it sounds like Donald Duck). However research done many years ago by the Royal Navy on communicating with deep sea divers breathing helium led to electronic circuitry to compensate for this frequency shift; the helium gives the divers a very high pitched voice. There is still no satisfactory solution to indexing on an ordinary compact cassette.

Digital technology
However digital technology offers the possibility of combining text and audio, and incorporating sophisticated searching and indexing facilities. For reading an audio novel, the main advantages of digital technology would be improved audio quality. For a cookery book, the new technology could offer facilities such as direct links to nutrition information. For an academic reference book the possibilities become even greater as long as the publisher had the resources to incorporate the extra facilities. The future of electronic books for the general population is surrounded by considerable hype. However American legislation has forced the main developers to consider the needs of visually impaired persons. So it is hoped that these developments will lead to an increase in accessible literature for blind people.

An important aspect of this digital technology is the ability to transfer data over high speed telecommunications links. For instance ADSL (asynchronous digital subscriber line) works over ordinary telephone lines but could transfer a typical audio novel in under 20 minutes using MP3 compression techniques; this might be economically attractive if the telecommunication network operators were to offer inexpensive call charges during the night for visually impaired persons. The precedent for such charging could be the free postage of material for blind people offered by the postal service. Third generation mobile telecommunication systems offer speeds up to 2 Mbit/s when in the vicinity of a transmitter, so this could be another method for delivering talking books to blind individuals.

Braille
The best known communication system for blind people is Braille which was developed by Louis Braille. A combination of six dots can only have 64 different configurations. This gives a problem in that many more than 64 different characters are used in modern printed texts; so, at times, more than one Braille character is needed to represent one print character. A Braille book is typically 20 times as bulky as the print edition. Therefore a form of shorthand is employed which uses 189 abbreviations and contractions giving a space saving of about 25%.   For computer use it is becoming common to use an eight dot Braille system which can represent 256 characters using only a single cell.

Since there is a shortage of skilled transcribers, computer systems are often used to translate text to contracted Braille which is then output on a special embosser. The algorithms for this translation are not simple since the rules governing the use of contractions depend on pronunciation and meaning. For example, there is a contraction for 'mother' which can be used as part of a longer word as long as it does not bridge a syllable boundary as in 'chemotherapy'

 

Since one of the greatest deprivations caused by blindness is lack of privacy, the provision of bank statements in Braille has been a very popular service for over 25 years. This system can be totally automated since bank statements are in a fixed format.  Layout is more problematic for mathematics and music. Since Braille mathematics is written on one line, the conversion of the layout on the printed page to a meaningful form in Braille is far from trivial. Braille music is also significantly different in layout from sighted music notation since the Braille reader has to read linearly.

There are about 13,000 people in the UK who regularly read Braille (NB this should be compared to the one million people whose vision is such that they could be registered as blind or partially sighted). For these people it is a very useful communication medium since it can be written as well as read by a blind person. This level of readership, which is typical of developed countries, is partly attributable to the difficulty in learning a new method of communication by people who lose their vision later in life. Another factor is that diabetic retinopathy is a significant cause of visual disability among those of working age, and diabetes usually adversely affects the sense of touch.

Tactile graphics
The increasing use of graphics in printed books, particularly school text books, gives problems. Although many diagrams can be converted to an embossed form, the process of reading by touch means that a diagram has to be tactually scanned and a mental image built of the whole diagram; this is the opposite process to visual reading where one looks at the overall picture and then reads the detail.

Reading machines
Some years ago NASA had a problem with communicating with astronauts during lift-off. The problem was of information overload using visual and auditory communication. Therefore they investigated the use of tactual communication; the project failed, but the research formed the basis of a reading aid for blind persons. The Optacon used a hand-held camera connected to 144 piezo-electric elements which gave a vibratory image of the print character; the task of recognising the character was left to the human. Its use has been limited by the low reading speed (typically 40 words per minute after extensive training).

Systems to recognise printed characters have been developed for inputting text to computers. Such systems have immediate application for visually impaired persons since the information can be output in synthetic speech, on a Braille display or in large characters on a screen. None of these systems can read hand-writing satisfactorily.

A facsimile (fax) machine can be used to transmit hand-written text to a central office where a human reads it back over the telephone. With the decreasing cost of fax machines, this technique is looking increasingly attractive as a means for providing a remote reading service.

Speech technology
Recent developments in speech technology have led to significant improvements in quality and accuracy, and a reduction in prices. This is important for people with disabilities since speech technology can be used for interpersonal communication, access to information and control of the environment.

Although the intelligibility of the available speech synthesis systems is quite high for a number of languages, there is evidence that significantly better quality should be achievable. Research is focused on naturalness, prosody and flexibility (eg different voices). Other important research areas are modelling of emotions and speech synthesis from the meaning of the text.

Speech recognition is difficult because:

Speech dialogue systems, in which speech synthesis and recognition are used in a man-machine dialogue, have been demonstrated for applications such as bank cash dispensers and hands-free voice dialers on public telephones. These systems are for the general public and therefore have to cope with significant variances between individual speakers. Current systems are limited to vocabularies of a few hundred words, but laboratory prototypes exist with vocabularies of a few thousand words.

If the system is trained for an individual speaker then accuracy dramatically improves, large vocabularies can be used and the cost comes down to a modest level.  Speech synthesis is a stable technology, but speech recognition is still substantially inadequate when compared with human capabilities particularly in noisy environments. Research on speech processing has had a significant impact on the design of cochlea implants as well as digital hearing aids. However there is a need for better understanding of user needs and matching these needs to appropriate research and development. There is also a need to use current knowledge in practical situations to evaluate potential benefits.

Computers
In the last twenty years, the most important change for many blind people has been the advent of the personal computer. With text-based operating systems, such as DOS, a blind person could access information with similar ease to a sighted person. The output from the computer could be in synthetic speech, a transitory Braille display or large characters on the monitor.  Many visually impaired people use their personal computers just for word processing. This gives them the ability to check what they have typed and to correct any errors.

Graphical User Interfaces
However the introduction of the graphical user interface, of which Windows is the best known example, brought a range of new problems. Early versions of Windows were partly inaccessible and required the blind person to have an understanding of the structure of the operating system. More recent versions of Windows have been more accessible because Microsoft has built in more accessibility features, but even so it is still not as easy as DOS for a blind person to use. Some blind people only use DOS, but most new software is not available in a DOS version.

Internet
Email, since it is text-based, has been very useful for many blind people since it is relatively easy to learn and to use. The world wide web offers exciting possibilities for accessing large quantities of information but there are problems. Firstly the blind user needs a suitable browser. The main problem is that many websites use graphics such that they are not meaningful when accessed by a text-based browser (eg with speech or Braille output). Guidelines have been produced for how to design accessible websites, but these guidelines are widely ignored by commercial organisations. So some websites are accessible, but these tend to be ones belonging to government departments. The popular websites, eg for home shopping and home banking, are still largely inaccessible.

Multiple Impairments

The number of people over retirement age in Europe is likely to increase by over 1% per year for the next two decades. With this increase in the ageing population, there has been an increase in the number of people with a visual impairment in addition to some other impairment.  The effects of multiple impairments varies considerably from one individual to the next, but can be summarised as the multiplication rather than the addition of the separate impairments.  Often a multiple impairment limits the range of devices appropriate for an individual. For instance someone with low vision and a hand tremor is likely to find a stand magnifier more satisfactory than a hand-held magnifier.

However there is an acute shortage of devices specially designed for this large and growing larger group of people. In times of war, the incidence of multiple impairments among young people rises significantly. It is not just soldiers, but also civilians including children, who are affected by landmines.

The proportion of children who have multiple impairments, rather than just a visual impairment, has risen in recent years since improvements in medicine have meant that fewer babies are being born with a single impairment, coupled with improved survival rates for babies with multiple impairments. The result has been that schools for blind children have had to adapt to cope with handling children with multiple impairments.

However these demographic changes have not been reflected in the activities of those undertaking research and technological development. This may be, in part, attributable to the difficulties of studying groups which are far from homogeneous. Also commercial suppliers of devices have found it less easy to sell devices to this group of customers.

The implication is that devices should be configurable or adaptable to meet the needs of the individual. Systems which are programmable, such as mobile phones, are easier to adapt to provide a range of user interfaces.

Deafblindness
The term deafblind is used in this booklet to refer to a person having combined loss of hearing and sight to such degree that he or she cannot make immediate use of facilities for those with impaired hearing or sight alone. This definition therefore includes people who have a combination of a severe hearing loss and low vision. Using this definition there are about 250 deafblind persons per million of the population in the UK.

For a device to be useful to a deafblind person, it does not necessarily have had to be designed specifically for the deafblind. However more and more devices for blind people employ audio output, such as synthetic speech, so there are fewer inexpensive devices with tactual output. For instance the number of electronic calculators with Braille output is falling since the cost of synthetic speech output has reduced dramatically in recent years. These trends have been to the advantage of blind people but have significantly reduced the choice available to deafblind persons.

Signals and alarms
These are a number of alarm clocks with raised markings on the dial and an electrically activated vibrator for the alarm. The vibrators are typically small electric motors with eccentric weights. Clockwork vibrators are not used in any of the standard products; the reason for this is not clear. The vibrator does not need to be directly connected by a wire to the clock - it can be triggered by a low power radio signal. This means that the vibrator can be worn on the body (eg like a wristwatch).

The simplest doorbell signallers involve a push-button being connected to an electrical device that then transmits a signal to activate a vibrator worn by the deafblind person. Sometimes the transmission is done via a closed loop aerial; this has a number of disadvantages including the high cost of installing the aerial and that the device only operates in the immediate vicinity of the loop. These systems are being superceded by radio devices. The input to the system is not necessarily a push-button; it is possible to use an infra-red detector or a pressure pad under the carpet.

A sound indicator is an electronic device that gives out a vibratory signal when it picks up an audio signal (eg a telephone bell) above a pre-set level. Usually the vibratory signal lasts for a fixed minimum time, and the amplitude of the vibration is usually constant (ie independent of the amplitude of the input signal). With some devices it is possible to tune the device to only pick up audio signals at or about a fixed frequency; this is useful in minimising the number of times the device is activated by picking up the wrong audio signal.

Other low technology devices
A small number of devices have been modified to give vibratory output. For example a liquid level indicator, light probe and typing aids. These are numerically very few because the development and manufacturing costs are high for a small national market.

Access to information technology
It was the advent of the personal computer with Braille or magnified visual output that opened up opportunities for a significant increase in access to information by deafblind people. Software for producing large characters on the monitor is relatively inexpensive, but Braille displays have remained expensive.

The basic mobile telephone has been of limited use to deafblind people. However the introduction of Universal Mobile Telecommunications System (UMTS) offers exciting possibilities if the services are affordable. For instance the ability to transmit pictures of where you are to a service centre and receive textual replies, could greatly assist a deafblind pedestrian in an unfamiliar environment. However not all technological developments are to the advantage of deafblind people. With analogue television it is possible to obtain Braille output of Teletext which gives basic access to the news. As yet, it has not been possible to obtain a suitable output from digital Teletext.
The Internet provides an alternative method for obtaining the news and other information. However, current systems for accessing the Web are not sufficiently user friendly for many deafblind persons to use unassisted.

Although technology could greatly increase access to information and the ability of deafblind people to participate in society, this is unlikely to happen unless there is a significant and ongoing investment in developing new devices and systems and making them available at affordable prices.

Inclusive Design

Increasingly blind people need to be able to use equipment designed for the general public; this includes ticket selling machines at unmanned railway stations, cash dispensers, and public telephones. In the foreseeable future, inability to use such systems is likely to increase the divide between the blind and sighted population; these systems could include next generation mobile phones, interactive television and electronic purses.

Therefore it is essential that equipment for use by the general public is designed to be accessible by as many people as is reasonably possible. With the increasing ageing population, this must include people with presbyopia as well as people with a combination of different impairments.

The 'inclusive design' message has had limited practical impact upon the area of information and communication systems and services. This is despite considerable effort being expended by various groups around Europe.  In the case of cash dispensers, the companies manufacturing the equipment see their customers as the banks purchasing their equipment. Even though they may have incorporated inclusive design features in their range of terminals, it is to no avail if the bank is not interested in offering it to their customers. Within the bank it may be a technical department which is responsible for selecting equipment for the bank, but it will be the local branches who have direct contact with disabled customers and who may provide a modicum of training in the use of the cash dispenser. Unfortunately local branch staff are unlikely to be aware of the technological possibilities for improving the accessibility of the equipment.

At the policy level it may be sufficient to specify that the equipment and services must be accessible to as many people as is reasonably possible. However this leaves open many questions including what does 'accessible' mean? Also what is 'reasonable'? Also it does not cover the often crucial question as to who pays for any additional costs such as training.

The development of guidelines for inclusive design of systems and services in the area of information and communication technologies is seriously hampered by the sparcity of sound scientific data about the needs of people with disabilities. What data exists is all too often based on inadequate sample sizes or inappropriate methodology. This is an area which is perceived to be low on academic content.

Industry wants guidelines to be pan-disability, but this will require greater collaboration between all the relevant organisations representing the different disability groups.  With new equipment and services which are only in the early stages of specification, such as third generation mobile communications, it is difficult to be precise. However if the influencing is left to the stage when it is clear what features will be incorporated, it is often too late to get anything significant changed.

Information for product designers may be detailed design guidelines (eg the maximum height and angle of a display so that it can be read by a wheelchair user). However this approach is only possible for established technology for which detailed design guidelines exist. In other cases it will be necessary to provide generic guidelines backed up by recommendations on how to test prototypes with a cross-section of potential users. For telecommunication designers the problems are shortage of time and lack of an established system for evaluating with disabled users. This is an area where user organisations could take a more active role in providing speedy evaluation of prototype systems and services.

New technology
The development time in telecommunications has been decreasing which means that the time between a project being proposed and the specification finalised is short. Also secrecy is considered essential by many commercial organisations. Therefore the possibility of having direct contact with the product specifier at the right moment is remote. So, in practice, it is essential to provide the information, or a signpost to it (eg a web address), in advance and hope that the recipient remembers it at the relevant moment. This can be assisted by the company having a design checklist which includes questions on the accessibility of the product by disabled users.

Policy documents from the European Commission are written in a special language which is difficult to understand by the uninitiated; only recently have some of the organisations representing disabled people taken on staff with the skills to interpret these documents. However these organisations frequently do not have the technical expertise to understand some of the implications. Therefore there needs to be some form of collaboration between those who understand the language and the regulatory issues, those who have a good grasp of the technology, and those with lobbying skills.

Standardisation
Standards are crucial in the telecommunications industry where there is a rigorous, but if sometimes slow, process for developing standards. In the television industry, the process is somewhat different in that the technical standards are frequently determined by bodies made up of only industry representatives and there is no policy for involving consumers. The situation is different again in computer software where the commercially dominant players set the de facto standards with apparently no consultative process. This means that convergence is going to involve a clash of cultures as well as the more obvious problems of integrating three different groups of technology.

Standardisation is slow, time consuming, lacks academic content and sometimes has limited direct commercial benefit. Academics shun the area since it does not produce research publications. Industry is hesitant about inclusive design standards work since they can see no short-term commercial benefit.

Industry and many government departments feel it is the role of the organisations of disabled people to assist with the implementation and awareness phases. However the disability organisations have often taken the view that they should be paid to do this work.

Since governments now see the primary purpose of standards as facilitating trade, the role of the consumer has become somewhat uncomfortable. Therefore legislation or mandatory regulation would appear to be the only practical way of requiring commercial organisations to adopt inclusive design principles. However the current trend is towards minimising regulatory control, and European legislation does not appear likely in the near future.

Public Terminals

The solutions to some of the problems of people with disabilities may appear trivial to a non-disabled person, but they can nevertheless have a major effect on the usability of a piece of equipment or access to a service. For instance many people would like a notch in the facia of the terminal so that they can lean their walking stick against the terminal without the stick falling over. Other problems require more complex modifications, but often solutions are available but not implemented.

Consistent user interface
For many disabled and elderly users, the most important aspect is consistency in the user interface of public terminals; this is particularly important for visually, intellectually and cognitively impaired users.

With public terminals, the user may only use it occasionally and has probably been provided with minimal training in the use of the terminal. What is 'logical' to the average user may be different from what is 'logical' to the designer, so it is essential to test any new user interface with a cross-section of potential users (including disabled and elderly people).

Allowing a choice of interface
To select a preferred interface such as audio instructions or large characters on the screen, the user could simply press a button or otherwise select from a menu on the screen; this is likely to increase the time taken to undertake a transaction if there are more than a few options. Another possibility is to store the user's preferences on a central computer and implement them as soon as the PIN (personal identification number) has been entered.

For card-operated terminals, it is possible to store the information on the user's card (the coding of user requirements is specified in the European standard EN1332-4), and this is in many ways more desirable than storing private information about a user on a central database. With a magnetic stripe card there is very limited spare capacity for storing this information (but this method has been used for storing the user's preference for displayed language), but a smart card (containing an electronic chip) has fewer restrictions on storage capacity so appears to be ideal for this purpose.

Many disabled users would like to be able to select and store their preferred interface whenever they use their card at a public access terminal. It is essential that information is stored on a card only with the consent of the user.

Locating a terminal
For a blind person, it can be difficult to find the terminal if they are not familiar with the environment. One possibility is to use a contactless smart card, carried by the blind person, to trigger an audible signal from the terminal at a distance of a few metres.

Audio interaction
Public access terminals can incorporate audio prompts in the form of 'beeps', to indicate an action. It is recommended that new equipment should provide a more sophisticated solution of using audio leadthrough in the form of a verbal set of instructions. Audio leadthrough can assist people with visual or cognitive impairments (and first time users). Message content should be chosen very carefully since a message that might be acceptable to the users for the first few times they hear it may become unacceptable when they hear it for the hundredth time. Many users with impaired hearing, who can only hear lower frequencies, can more easily hear a male voice than a female one.
If audio output is used to provide private information to the user, then it should be through a telephone handset located at the terminal or through a headset connected through a standard mini jack to the terminal; however, it is essential that the position of the jack socket is standardised. If a handset is provided, inductive coupling and amplification should also be incorporated.

Card orientation
Blind persons, and many elderly persons, have problems in inserting the card in the correct orientation; this is a particular problem on cards which are not embossed. However there is a European standard for an orientation notch (EN1332-2) in the card:

Braille
Braille instructions on outdoor terminals have limited value in cold weather since tactual sensitivity is dramatically reduced with decreasing temperature. The estimated number of Braille readers in Europe is less than 200,000 so although useful for some blind users, Braille is not a total solution for all visually impaired users.

Reading screens
People who wear bifocals find it difficult to read the screen of most public access terminals, since neither lens gives a focussed image for the distance between their eyes and the screen. In addition many people leave their spectacles in the car or do not wear them in public. So the number of people who have problems in reading the screen is much more than those considered 'blind' or 'low vision', who constitute about 1.5% of the population.

People with low vision should not be prevented from getting their faces close to the screen. However it is possible to increase the size of the characters on the screen for individual customers who require this facility. This can be done by selecting this option from a menu or preferably by storing this information on the customer's card. With touchscreen systems, it could be arranged that holding one's finger in the top left corner for at least two seconds indicates that one would like double size characters on the screen. Ambient light, such as from an illuminated sign above the terminal, can cause problems if it results in glare or reflections from the screen.

Moving text on a screen can be very difficult to read for someone with even a mild sight impairment, so it should be avoided whenever possible.

Speech output
Digitally stored speech can give very good audio quality, but it is effectively limited to pre-stored messages. Full vocabulary synthetic speech is often difficult to understand for the naïve user, particularly if they have a hearing impairment. Non-confidential information can be output on a loudspeaker, but the volume should be a function of the current ambient noise level; this is less of a problem with handsets or headphones.

One technological possibility would be for a disabled user to have a hand control unit with an infra-red or radio link to the terminal. It may be that Bluetooth becomes the standard interface, but still there is a problem in persuading service providers to fit it to all terminals (which would include retrofitting to existing terminals).

Text on screens
Displayed text should use simple, large, bold fonts in upper and lower case characters. Displayed messages should be simple in sentence structure, use natural language, and any graphical symbols (such as icons) should be accompanied by text.  Information, which is sensitive and private to the cardholder, should not be visible to any other person; screen filters, which act like a slatted blind and restrict the user to be directly in front of the screen, improve privacy but often at the expense of visual quality. However users may wish to display information with a large character size, but they should be made aware of the privacy problem.

Keypads
Standard layout of keypads is essential for visually impaired people and highly desirable for other users. To help blind persons, there should be a single raised dot on the number five key. However this does not solve the problem of there being two common layouts for the numeric keys (ie the telephone and the calculator layouts); it is recommended that the telephone layout is used exclusively on public access terminals.

Ideally keys should be internally illuminated when the terminal is waiting for input from that keypad. There should be some form of feedback on key input (eg a beep and/or tactual indication). Tactile feedback can be provided by a gradual increase in the force, followed by a sharp decrease in the force required to actuate the key, and a subsequent increase in force beyond this point for cushioning.

Allowing more time
Many elderly people and those with a cognitive impairment do not like to be rushed or to think that they are likely to be 'timed out' by the machine, so it is necessary to allow for such people to use the terminal at their own pace; this requirement could be stored on the user's card.

Touchscreens
To help elderly people and those with hand tremors, key fields should be as large as possible and separated by a 'dead area'. There should be high contrast between touch areas, text and background colour. Avoid using a pretty picture as background — it is a menace to anyone with poor vision or someone reading the screen under difficult conditions (eg in bright sunlight).

For blind users, one possibility is to arrange that holding one's finger in a specified corner of the screen for at least two seconds initiates speech output (NB this must be a different corner than the one used to request large characters on the display), or tapping twice in the corner. Another method would be to store this requirement on the user's card.

Touch screens can either be triggered by insertion or withdrawal of the fingertip. With the latter system, it is technically possible for the user to pass their fingertip over the screen and get speech output describing the active area they are touching at the time. Then the system is only triggered by withdrawing the fingertip from over an active area.

Printed receipts
To aid visually impaired users, receipts should have a minimum font size of 12 point with a clear typeface with upper and lower case text, but 16 point would be preferable if space permits. It is important that the print has good contrast on opaque paper with a minimum of background pattern. A common complaint is poor print quality on receipts which can be a result of the printer ribbon not being replaced regularly.

Convergent Systems

There has been much speculation about the impact of the coming together of computing, telecommunications and broadcasting, but as yet it has had little practical effect. However this will change over the next few years, and it will open up new possibilities for services to help visually impaired people.  It is difficult to predict what new services will be available since the limitations will be mainly commercial viability rather than technical feasibility.

Mobile phones
Mobile telephones increasingly require the user to read a small liquid crystal screen to operate many of the functions in the phone. Although the phones incorporate increasingly powerful microprocessors, manufacturers have not seen a commercial opportunity in providing models which incorporate speech output of the messages normally displayed on the screen. However there are some indications that this may change because car drivers are seen as a significant market segment.

WAP (wireless application protocol) can be used for financial transactions such as reloading an electronic purse. Extra functionality to suit visually impaired users could be built into the terminals, but this in itself is unlikely to provide full access to services. Therefore it will be necessary to modify the server or proxy server. The WAP User Agent Profile Specification covers aspects of the technical interface and the User Preference Profile concerns content selection (eg the user is interested in receiving sports scores); neither of these profiles covers the needs of people with disabilities.

GPRS (general packet radio service) is a high speed packet data technology which will permit data transmission speeds of up to 100 kbit/s over the GSM (global system for mobile communications) network. This is well suited for frequent transmission of small amounts of data. However it could be overtaken by UMTS (universal mobile telecommunications system).

UMTS is the next generation of mobile telecommunications system which will have seamless operation between terrestrial and satellite links. It will provide high speed access to the internet with data rates of up to 2 Mbit/s for a stationary terminal, less when on the move. It will include packet data transmission with the potential to adjust bandwidth on demand for asymmetric traffic. In the UK the network licenses have been sold by the government for vast sums (the first five licenses sold for over £22.5 billion) which will have to recouped from the users.

UMTS will permit the transmission of video. For instance a blind person might send a picture to a service centre where a sighted person could give instructions on how to reach the desired destination. Another possible use for UMTS would be to download talking books during the night; a typical novel would take about 20 minutes to download using MP3.

Electronic purses
For some time pre-payment cards have been in general use for applications such as public telephones. These disposable cards are loaded with a fixed amount of value, which are then decremented during use. The next development was to make the cards reloadable which can be done at specialised terminals or automated teller machines (cash dispensers). Then it was only a small step for the cards to be used for more than a single application; these cards are called electronic purses.

However these systems vary significantly depending on the type of organisation operating the service. Historically the banking organisations have placed great importance on security, whereas public transport operators have been more concerned to minimise the time taken to complete the transaction.

Some electronic purse systems offer the facility to transfer funds between the card and the customer's bank account using a screen phone. Screen phones can be modified to be accessible by blind people, so this method of loading a card could be the preferred mode for many blind and partially sighted users.

For visually impaired persons, the main problems with electronic purse systems relate to the user interface. In particular many of the devices, such as balance readers and electronic wallets, have poor contrast visual displays which also pose problems for many elderly persons. One possibility would be to have special versions of the balance readers and wallets for those who cannot read the standard versions. Such a special wallet / balance reader might include:

A significant aspect of electronic purses is that the user does not need to have a bank account or even be credit worthy. This is likely to make electronic purses the preferred method of remotely paying for shopping by many older visually impaired persons. Another attraction for this group of customers is that as soon as the transaction has taken place, they can check the remaining balance on their electronic purse; unlike credit or debit cards, there is no risk of an unexplained item appearing on a future statement.

Interactive digital television
Interactive television is attracting considerable investment as it is seen as a significant step in selling new services to customers who may not be computer users. The UK government envisages that it will be a major method of interaction between the public and the government within five years.

Traditional television can be characterized as one-to-many whereas the internet would be characterized as many-to-one. As yet interactive television is frequently just an enhanced one-to-many system with uncertainty as to how to satisfactorily also be a many-to-one system.

Some systems offer email which is proving popular among those who do not have access to a computer or have no inclination to use one. Currently there are no facilities for enlarging the text or changing colours which gives problems for many visually impaired users.

In the UK, home shopping has taken off faster on interactive television than on the web; this is being attributed to viewers being less anxious about credit card fraud through the television set than the Internet.

Convergence
In the future, the remote control for the television might be a mobile phone, connected by Bluetooth, into which is inserted the electronic purse to pay for goods and services.

Future Research

Over the next ten years, there are likely to be improvements in the medical prevention and treatment of eye conditions, but the increase in the ageing population will probably mean that the net effect is that there will be a larger number of people with visual impairments.  Many older visually impaired persons have seen little benefit from the advances in the area of assistive technology. If they use assistive technology, beyond conventional low vision aids, it will usually be the low-technology low-priced devices to assist in daily living.

A major problem has been in transferring prototypes from the laboratory into products generally available at affordable prices. Unless new funding mechanisms are developed to facilitate this process, many visually impaired people will not benefit from the scientific and technological research being done on their behalf.

Universities discourage research on 'simple' devices because there appears to be little academic content. Industry often does not perceive there to be a significant commercial market. This means that this area has been left largely to the non-profit organisations.

What is needed are studies of the problems faced by visually impaired people, and the development of novel inexpensive devices to meet these needs. This will require imagination as well as a knowledge of appropriate production processes. Last, but not least, all this needs to be linked to a marketing strategy which reaches the potential consumers. For too long, visually impaired people have had to make do with products which are poorly designed.

Another aspect is the desirability of developing products which are attractive to non-disabled users. It is worth noting that the fountain pen, typewriter and long-playing record were originally developed for use by blind people.

There is a particular need for devices for people with more than one impairment. The problem is that this is a far from a homogeneous group, so it is likely to involve developing devices which are adaptable.

Many research workers find it easier to study the needs of people who are totally blind since it is difficult to do an accurate comprehensive functional assessment of someone with low vision. This has been particularly noticeable in the area of research on electronic mobility devices. There has also been a tendency to look for purely technological solutions to human problems.

Vision enhancement
An area of research which appears promising is vision enhancing systems in which the user is presented with a display with enhanced contrast of the objects in the near field. Such a system would use a body mounted camera and a head-up display. The existing devices are too expensive and the usability aspects need to be improved. Also such a system could be designed to partly compensate for loss of colour discrimination.

Cortical stimulation
Research is being done on connecting a video camera to the human brain. One approach was to implant a number of electrodes in the brain; this proved problematic, so more recent research has concentrated on methods of stimulating the optic nerve. This research is important but it is unlikely to produce systems which are widely available within the next ten years.

Vision substitution
Vision substitution can involve converting a video signal to a non-visual form which can be auditory, tactual or some combination of the two. Since both the auditory and tactual channels have far lower information capacity than the visual channel, it is necessary to process the signal from the cameras before it is sent to the non-visual display. Ideally this processing should include edge detection and object recognition. With increasingly powerful wearable computers, vision substitution systems look very promising if the appropriate algorithms can be developed.

User interfaces
The ability to modify the user interface will be crucial if new systems are to be accessible to visually impaired people. In particular such a facility will be essential in areas such as interactive television and the next generation of mobile communications.

Wireless coding
Systems, such as Bluetooth, will permit communication between devices such as mobile phones, televisions, central heating controllers and assistive devices. However this is insufficient since there also needs to be a standard method of coding information to be sent to and from assistive devices.

Orientation systems
It is in the area of orientation systems that exciting but practical developments can be expected in the next few years. This may involve a combination of satellite and mobile telephony technology coupled with an electronic map accessed over a UMTS link. However it will be important that service delivery, including training, is developed at the same time.

Graphics
A major research area relates to graphical representations. The trend for systems for sighted people is for the increasing use of graphics, but research on non-visual presentations is lagging far behind. For people with low vision, more research is needed on how to optimally present visual graphics; this may involve transposing colours for people who are colour blind.

Internet
The world wide web is partly accessible for users who have to rely on non-visual output. However new modes of presentation and the rate of development could mean that access could get more difficult. This is a serious problem since the web has the potential for significantly narrowing the gap between blind and sighted people regarding access to information.

Virtual reality
In the longer term, technological developments in other fields could have benefit for those working with visually impaired persons. For instance, virtual reality technology could provide realistic simulations of visual defects including fields, acuity, colour discrimination and effects of illumination; in addition, multiple impairments could be simulated. Such a system might be useful for evaluating proposed public buildings.

Virtual reality technology allows people with sensory disabilities to perceive what they might not otherwise be able to since it can gather information in a sensory modality in which they are impaired and deliver it to one where they are not. It also has the potential to be used as a training aid for skills such as spatial co-ordination and orientation.

As intriguing as virtual reality is, the enabling technology is still crude. Major technological hurdles exist in the area of tracking a person's motion and position in a non-intrusive way, in displaying high definition stereo colour images of the scene covering the user's peripheral vision and, in the area of image generation, speed for a smooth and realistic animation of the scene. Tactile output and the construction of physical images, to support the visual images in virtual environments, require further development to produce realistic sensations.

Over the next ten years there are exciting possibilities for improving the quality of life for people with a visual impairment, but there are hurdles to be overcome to ensure that the appropriate research is undertaken and the results of this research reach the potential consumers.

 

References

Gill J M A Vision of Technological Research for Visually Disabled People. ISBN 0 9516611 4 0, March 1993.

Gill J M The Forgotten Millions: Access to Telecommunications for People with Disabilities. ISBN 92 826 7399 5, March 1994. www.stakes.fi/cost219/forgmi94.doc

Roe P R W, Sandhu J S, Delaney L, Gill J M & Mercinelli M User Needs: Consumer Overview. In Roe P R W (ed) Telecommunications for All. COST 219, October 1995. www.stakes.fi/cost219/Telall96.doc

Gill J M The Forgotten Customers: One in Ten have Difficulty with Packaging. Food, Cosmetics and Drug Packaging, August 1995. www.tiresias.org/reports/packag.htm

Gill J M Which Button? The Design of User Interfaces for People with Visual Impairments. ISBN 1 86048 023 3, August 2000. www.tiresias.org/controls

Gill J M Telecommunications: The Missing Links for People with Disabilities. ISBN 92 827 5115 5, February 1996. www.trace.wisc.edu/docs/missing_links/mlhome.htm

Gill J M (ed) Domestic Telecommunication Terminals: Access by People who are Blind or have Low Vision. COST 219 UK Group, December 1997. www.stakes.fi/cost219/wgvi.htm

Gill J M & Shipley A D C Telephones: What Features do Disabled People Need? ISBN 1 86048 020 9, August 1999. www.tiresias.org/phoneAbility/telephones

Gill J M Financial Services and Visually Disabled Persons. ISBN 0 901797 65 0, Sept 1991.

Gill J M An Orientation and Navigation System for Blind Pedestrians. ISBN 1 86048 008 X, April 1996. www.tiresias.org/reports/mobicgl.htm

Gill J M (ed) Mobility of Blind and Elderly People Interacting with Computers. ISBN 1 86048 006 3, April 1997.

Gill J M Non-visual Screen Representations. In Issues in Telecommunications for People with Disabilities. ISBN 92 826 3128 1, 1991. www.stakes.fi/cost219/isscon91.doc

Gill J M Access to Graphical User Interfaces by Blind People. ISBN 1 85878 004 7, October 1993.

Gill J M The Design of Man-Machine Interfaces for Use by Visually Disabled People. International Technical Aids Seminar for the Visually Disabled, July 1995. www.tiresias.org/reports/japan.htm

Gill J M Approaches for Influencing the Design of New Telecommunication Systems and Services. International Conference on Smart Homes and Telematics, February 1999. www.tiresias.org/reports/approach.htm

Shipley A D C & Gill J M Call Barred? The Inclusive Design of Wireless Systems. ISBN 1 86048 024 1, 2000. www.tiresias.org/phoneAbility/wireless.htm

Gill J M Access Prohibited? Information for Designers of Public Access Terminals. ISBN 1 86048 014 4, May 1997, revised March 1998. www.tiresias.org/pats

Gill J M & Currie K Smart Cards and Terminals. In Roe P R W (ed) Telecommunications for All. COST 219, October 1995. www.stakes.fi/cost219/Telall96.doc

Gill J M Design Features of Terminals to Improve Accessibility by Visually Impaired Persons. Vision 99 Conference, July 1999. www.tiresias.org/reports/terminal.htm

Silver J H, Gill J M & Wolffsohn J S W Text Display Preferences on Self-Service Terminals by Visually Disabled People. ISBN 1 86048 001 2, November 1994. www.tiresias.org/reports/atm.htm

Gill J M, Silver J, Sharville C, Slater J & Martin M Design of a Typeface for Digital Television. Third Tide Congress, Helsinki, June 1998. In Placencia Porrero I & Ballabio E Improving the Quality of Life for the European Citizen. IOS Press, ISBN 90 5199 406 0, 1998. www.stakes.fi/tidecong/632gill.html

Gill J M The Use of Electronic Purses by Disabled People: What are the Needs? ISBN 1 86048 017 9, August 1998. www.tiresias.org/epurse

Gill J M (ed) Guidelines for the Design of Screen and Web Phones to be Accessible by Visually Disabled Persons. ISBN 1 86048 018 7, December 1998. www.tiresias.org/reports/webphone.htm

Gill J M   Priorities for Technological Research for Visually Impaired People.  Visual Impairment Research, ISSN 1388-235X, Vol 7, Nos 2-3, August-December 2005, pp 59-62.

 

Websites

Trace Center, University of Wisconsin
www.trace.wisc.edu

Tiresias, RNIB Scientific Research Unit
www.tiresias.org

COST 219  Access to Telecommunications
www.cost219.org

 

 

 

 



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