University of Edinburgh

Vision for Doing

Assessing Functional Vision of Learners who are Multiply Disabled

Part 3: Topics Revisited

Appendix II Use of computers

Use of technology

Frequently it is suggested that computers offer a useful way of working with those who are multiply disabled. This may be for instance, in introducing notions of cause and effect, to enhance the possibility of the learner receiving contingent feedback from his world. In the main text we looked at some specific ways in which technology may be helpful when developing activities to be used with those who have multiple disability. In this short section we consider some general issues to do with the use of technology. Here we will consider the use of computers. In Appendix I we commented on Switches and Interfaces, another aspect of technology in common use with those who are multiply disabled.

Why use computers?

By now, it should be obvious that access to a computer is by no means necessary in order to understand how well, and in which ways, the learner with multiple disability may see. Nor, if only computers are used to understand a learner's functional vision, would the results be at all sufficient. Nevertheless, both you and the learner may have access to a computer, and would like to incorporate into the learner's current activities some sort of use of new technology. Let's explore some of the advantages and disadvantages of using computers, for both assessing and using the vision of learners who have multiple disability.

Advantages of using computers


As a different learning environment, the computer can become a tool to observe how quickly the learner understands and consolidates a new source of information. It is likely that the computer will be housed in an area different from the usual surroundings. Travelling to the equipment may itself offer a means for looking at anticipation. Does she seem to know what is coming next? Anticipation may occur at many levels. She may recognise particular software, or peripheral equipment (like a colour printer), or the area in which the work-station (computer plus its extras) is housed. The computer activity - if motivating to the learner can then be part of a signing, signifier or symbol display for communication purposes. And the route to its location can become part of a mobility game.

Single plane

A second advantage is that most of the visual activities take place in one place and in one plane (although this is not the case for the keyboard, concept keyboard, joystick or switches) . The learner can then position herself at the optimum distance for seeing materials. Objects in the real world tend to be in cupboards or drawers, behind or underneath other objects. The activities carried out on a table top occur at varying distances, requiring continual re-focussing to be made. A computer screen does not suffer from these disadvantages.


A third advantage is in the way in which material is presented on a computer screen. The shapes, colours, words, pictures do not 'borrow' light from lamps, daylight or overhead lights. The screen provides its own lighting. Therefore no matter how near the learner approaches to the screen, she cannot get in her own shadow. (Problems of safety are discussed below). This backlighting, as it is known, allows enhancement of contrast and lighting.

Quick change

A fourth advantage is in the potential for good programs or software to facilitate rapid change of different shapes and colours. To change these conditions using ordinary materials might take a very long time and prove expensive. (Always assuming that you are not going out to buy a computer especially for this activity!) Some software may have features which allow individual records to be kept for each learner to chart improvement.

Maximise interaction

Good software will not only allow some level of interaction between learner and computer, it will also have different ways for learners to perform that interaction. For instance, some will be able to use a keyboard, others will require switches, others still will have only their voice to make things happen. To maximise the understanding that the learner's actions will have an effect on the screen, the use of a Touch Screen is recommended. The link between action and effect is then more direct.

Disadvantages of using computers

Before embarking on using computers, there are some limitations to consider. You should assess the costs of these versus the benefits outlined above before arriving at a decision for your learner.

How long is too long?

Being fixed in one position in one room or one area, as most machines are, can be extremely limiting if you find the learner does not respond. The temptation is to leave the learner on it a 'bit longer'. The result can be a kind of computer constipation. Whilst interacting with a computer, it is often difficult to duplicate hard won optimum seating and positioning. Though you should not be afraid to position the equipment in ways best suited for that learner.

What constitutes use?

There is also a huge dimension along which a learner could be said to be 'using the computer'. The two week old infant of one of the authors consistently pressed keys in order to obtain a beep from the screen. By no stretch of the imagination could she be said, on this basis, to be able to use a computer. Is training in that kind of limited cause-and-effect an improvement on trying to establish more natural forms of communication?

No standardisation

Another disadvantage lies in the fact that there are many different makes (and makes within makes) of computers on the market. The chances are that the lovely bit of software you saw running at an exhibition does not work with your machine. Even for the same machines, different makers of software may have different understandings of the learner. An especially helpful line that has recently been taken is for one or two software writers and distributors to adopt a standard across different programs.

Not real world

Other limitations have to do the ways in which information is presented on screen. We have already indicated as an advantage that, by using a computer, information can be presented in a fixed plane. But this can also be a disadvantage. For the real world is not confined to one fixed plane. It extends in distance, depth and direction, is made up of objects of varying size, shape and texture. Understanding of concepts such as in front and behind, up and down, backward and forward, will be wildly different if taken directly from a computer screen. For example, the 2-dimensional representation is that up means forward and down means back. To one with learning difficulties, it is not immediately obvious why this should be the case.

Expected learner responses

Major limitations exist as to how software is set to interpret responses. Some software will allow its operation by switches connected to the computer. Press a switch and an effect is produced. At first glance, switch operation seems a simple concept to attain. There are, however, many ways in which a switch press can affect the running of a particular piece of software. In all probability the ways in which one switch activates an effect will be quite different from that of another program's use of switches.

And yet the learner is expected to understand these associations. The problem is that people who design such software often have in their heads some intuitive assumptions about the ways in which those who are multiply disabled learn and perceive. Often they are wrong.

Stationary objects which fill up colours with no interactive control by the learner are not motivating. Various learning parameters have to be considered. These include: how long the stimulus comes on for (duration); how quickly following an action by the learner the stimulus will appear (latency).

If free presentations are received by the learner's interaction, how many times or how long a switch is pressed with no stimulus effect. Careful consideration needs to be given to the appropriate response measure or input. Decisions have to be made as to the aims behind the activity.

(Other aspects of switch control are discussed in Appendix I).

Some suggested uses of computers


Before being filled with despair thinking computers are of no value, let us retrieve the situation a little. Where relevant more specific details are given in the Sections of Chapters 6 and 7.

Awareness and Attending

Following the structure used in these earlier sections, computers are most helpful in encouraging awareness - that there is something out there. Secondly, they are helpful in encouraging directed attention. In a darkened room, they may be very attractive to those with severe visual impairment, often acting as a source of motivation.

Changing switches

Where switches are being considered, then it may be helpful to have two rather than one modality of output. One action may result in a change visually; a second may result in sound change through controlling cassette tapes containing favourite music. As the choices would operate across different sensory modalities, this would serve as an introduction to a two choice system. The switches operated should vary along criteria such as colour, material, and size. This could then serve as an early introduction to a Concept Keyboard.


If the taped sounds are rhythmical patterns as opposed to melodies, then stimulus duration can be two or three seconds. This is roughly equivalent to how long it might take the learner to carry out the manoeuvre necessary to operate the switch. If, however, the tape is of a melody (East Enders has been a favourite for many for several years), the duration of the melody should be long enough for the tune to be recognisable, around 5 seconds. One or two in every ten presentations should be made without the learner having any control over it. Moreover, once or twice every ten times, switch operation should not result in any effect. Compare response to a moving versus a stationary target. Use sound with and without vision to contrast.


Many programs claim to enhance localised responses - that is directional responses such as scanning and tracking of a visual stimulus. Often in reality, the learner sits staring at one spot or randomly fixating areas of the screen rather than following the stimulus. Here you might look for programs which encourage differential responses, and avoid those which carry on running regardless of the learner's activities.

Touch Screen

Use of a Touch Screen with relevant software promotes use of differential responses. As with many other areas of assessing Vision for Doing, you will need to experiment to achieve optimum positioning. A learner who is immobile may require the monitor to be raised if using a standing frame for position.

Microphone as a switch

For learners who experience difficulty in vocalising, some software may be operated by voice input. The most primitive is that which treats the microphone input as a simple on/off switch. Any vocalisation will result in the program carrying out its appropriate command. Some variation is possible in controlling the kind of sound needed to operate the device. Of course there is a very long way from operation of this kind of program to the point where individual utterances are taken to have shared intention and meaning. Nevertheless it may be a useful tool for those who have breathing difficulties in vocalising - especially in s versus sh. It is important to enlist the help of a communication therapist.

Visual scanning

Computers are also valuable in promoting localising through preventing the learner from using tactile information when scanning. Many learners habitually use tactile information to substitute for or to augment visual input. If they are motivated by a computer program, they may come to use visual information to locate shapes and patterns.

Recognising and Understanding

Concept Keyboard

Some software is also useful to promote recognition of familiar materials on screen, requiring a specific response to be made. Finally, they may aid understanding the meaning of a stimulus object on screen. In both of these areas, the use of a Concept Keyboard may prove useful. This is a board with an overlay which replaces the standard computer keyboard. It can be programmed to give the same response when touched anywhere on its surface. Alternatively, it can be divided into smaller squares, by which a touch on each square may be produce a different result. The overlay (which may be made of paper or other thin material) might have contours, pictures, numbers, shapes drawn or printed on it or in tactile or raised form. Or you might use signifiers to stand for real objects, or small objects themselves. At this stage, you might want to consider the use of a speech synthesiser which provides modest speech quality, if moving to use of phrases, whole words or letters.

Functional communication

In all of these areas, attempts should be made to have real communication associated with these computer events. For instance, instead of saying 'stop' , it may be possible to introduce a sign for 'stop' and then stopping the activity. This encourages control. The sign can be presented visually if there is residual vision or - for the more severely visually impaired - tactually by modelling on the hands.

Sources for further information

To explore this area properly requires a lot more discussion than the paltry amount we have devoted to the subject. There are a variety of sources of relevant materials, a few of which are presented in the accompanying text. Consult these sources to gain a wider understanding of the topic. These include further reading and both commercial and non-commercial sources for hardware and software.