Vision for Doing
Assessing Functional Vision of Learners who are Multiply Disabled
Chapter 7 Assessing Vision for Doing
Section 14 Learner's Responses to Contrast
Aims of Section 14
In this section we consider how to make best use of changes in contrast in the learner's world. We will also include some assessment of the learner's perception of colour. There is some evidence to suggest that some people may have good ability to see the fine detail of objects but have difficulty when even quite large objects are poorly contrasted against their background. It is usually good teaching practice to use relatively good contrast between an object and its background. Nevertheless, it is often the case that a person with good sight believes a contrast to be strong, whereas the person with poor sight believes the contrast to be poor (we saw an example of this in Chapter 1, where we discussed a child's problem with a blackboard).
Optimising the use of contrast seems a simple problem: to solve it surely all one needs to do is arrange activities that ensure maximum difference using black for a foreground and white for a background. Or is it such a simple problem?
How to useSection 14
Begin with materials that are highly contrasted and are real objects. These include bright orange balls; black against orange; black on white (and try white on black); sky blue with black; white on blue and so on. The shapes to use are not dictated by those given on the diagram - you will be using real objects. Be flexible and be prepared to try again another day. To start with use fairly large objects and work down. Try not to change both the contrast and the size of the object in one step. You may want to postpone changes in size until Section 15.
What to observe
Turn to the diagram. For your observations of the learner, as a guide you will be using the sketch at the top. The one on the left is an example of using high contrast - black on white as stripes, checks, large spots and so on. The middle diagram at the top shows medium contrast; that on the far right indicates low contrast - such as cream or beige against a white background.
In the middle of the page there is a table allowing you to record the results of your observations. This is where to record whether there is a response to the object and for which contrasts - high, medium and low. If you are sure it has been noticed, tickConsistently. If inconsistent, tickOccasionally ; if not noticed, then tick Never.
After this, it need not be during the same session, try out various colour combinations, such as black foreground with orange background; yellow foreground with blue background, and others. Do not forget white foreground with black background. Try to identify what works well with that individual learner. Record this in the box at the bottom of the diagram. Often you will be following up your own hunches, gleaned from sessions when you have thought the learner did not function as well when using certain colour combinations.
As we stressed before, remember not to allow previous items to influence subsequent items.
Transferring results to Section 18:
As with the other sections, you now have to decide what the results of your observations mean for the Summary Chart in Section 18. In that Summary Chart, you will find that in the row for Section 14 there is space to tick under a variety of boxes. It depends on which particular contrast you are using. Consistent response to objects that are high contrast allows you to tick Aware. Those to medium contrast to tick Attend; and low contrast to tick Localise.
As before, if the learner makes a very specific response (eg; naming the object being presented), this would mean he could Recognise through vision. If you happen to have additional information by all means tick boxes in the filled areas as appropriate.
No response with any contrasts?
If the learner Never shows any response, try again on subsequent occasions with different objects and in different lighting conditions (that is in other Settings). You should still try the remaining sections in this chapter. If these too result in Never you should refer back to the curriculum suggestions in Sections 9, 10, 11, 12 and 13.
OR score localise if:
she notices objects of high, medium and low contrast Consistently. In this case go to the Summary Chart (Section 18), find row 14, and tick Localise. In this case it is very likely that you will be able to obtain additional information to show that she can also Recognise.
OR score attend if:
the learner notices Consistently objects of high and medium contrast, but not low contrast. In this case go to the Summary Chart (Section 18), find row 14, and tick Attend. Note for your own records any colour combinations that present difficulties. You will probably want to return to the suggestions for curriculum development given in this present Section.
OR score aware if:
the learner shows responses only to high contrast objects. If so, go to the Summary Chart and tick Aware . Note any colour combinations that give the optimum response. Then move on to Section 15. In this case you may well want to return and use the curriculum suggestions given in this present Section.
AND score Aware if:
He shows responses Occsaionally to objects of the three contrasts. Again, go to the Summary Chart, tick Aware in the appropriate row.
Where to go now?
Having noted the results of your observations and transferred these to the Summary Chart, you are then ready to make a choice. The choice you make will depend on the results you obtained.
you can skip the remainder of this section and proceed directly to Section 15, dealing with responses to objects of different size. By doing this you will continue your assessment of the learner's use of Vision.
postpone further assessment and read the remainder of this section. In it we suggest activities for curriculum development.
Developing a curriculum
General comments about use of contrast
First, some general comments about contrast. As we mentioned these earlier in the book (see Chapter 2) we will confine ourselves to a few main points:-
- almost every activity carried out will present more than one contrast. Keep an open mind on other sources of contrast which may be interfering with your intended contrast;
- a plain background makes it easier to distinguish objects in the foreground. A patterned surface for a background offers less contrast between object and background. The more 'busy' a pattern, the more difficult it is to distinguish the object(s) (see Figure 2.3 in Chapter 2);
- in many cases, movement of the object relative to its background often helps the object to stand out (see Figure 7.14.1);
- similar colours merge together. For instance, the clothes one wears may make it very difficult for a learner to locate one's presence. You may want to have available a jacket, apron or overalls easily distinguished by the learner;
- try to avoid too many shadows;
- depth changes (such as steps and stairs) may be accentuated by improving the contrast between two surfaces;
- experiment with these in different Settings such as in a classroom, out shopping, in the garden.
The notion that a learner would not make use of any residual vision is, it would seem, counter-intuitive. After all, if vision is so useful, why would the learner not make maximum use of it? Long experience of poor information given through sight can however lead the learner to ignore any potential success that this source of information could give. Often one finds a different picture emerging with a learner having lunch. In this situation he may be motivated to use vision. Hence the emphasis placed throughout this book on trying out different Settings with a learner, rather than relying solely on touch or sound stimulation.
Having set out some general comments on using contrast we can now turn to more specific areas of curriculum development.
You will be interested in following up this section if results in the Summary Chart suggest the learner is functioning at the level of only being Aware of the objects and events in the world. You will probably have found only response to objects which are highly contrasted.
A large white card against which dark objects are presented may be used to accentuate contrast. Gloss surfaces should, however, be avoided as these may reflect too much glare. For a child who is lying down or inclined over a wedge, a white sheet or towel may be useful as a background.
Recall the comments on cortical visual impairment (or cortical blindness) made in Section 10. These learners may benefit from very highly contrasted objects, and experimenting with the use of colour. They may not perceive an object as such, instead perceiving disembodied colours. Enhancing colour contrast helps to accentuate the boundaries of objects from their backgrounds.
You will be interested in following up this section if results in the Summary Chart suggest the learner is functioning at the level of only being able to Attend to the objects and events in the world. You will probably have found Consistent responses to objects which are of medium contrast.
Where your observations have suggested that in situations which are motivating, the learner seems to attend to poorly contrasted materials, try associating the introduction of an object with a pleasurable experience. Just what that pleasurable experience might be will be different for each learner. Use these in an opportunistic fashion to encourage the learner to look carefully, to scan and search.
In an earlier section we showed how to increase awareness of hands using reflective tape. Where the learner is able to see highly contrasted surfaces, you may use this idea but with different materials on the hands. The hands would in this case be outlined with non-toxic paints or markers. Any hand movement the learner makes will have a pronounced visual association. At first the learner may be encouraged to see the results of his 'pointing'. If successful, it may be possible to have him point to a certain spot. Contrast cues can then be varied depending upon the level of vision. To do this use different foreground versus background colours for papers and paints.
If encouraging the strengthening of hand and leg movements in leading to crawling, and free standing, use towels as props under the arms allowing the child to push up more freely. Therapy balls may be used in conjunction with a well-contrasted floor covering. Familiar high-contrast materials increase visibility of the surroundings, thereby lessening feelings of vulnerability.
Glove-puppets can be adapted so that features are highly contrasted. For the learner whose language is affected, through hearing impairment or other difficulty, movement of the puppet may be made consequent upon her vocalisation. The specific kind of vocalisation would depend upon the ability of the learner. For some, the action of the puppet may be gross and related to the child producing any utterance. This can later be refined as success is obtained. Speech and language therapists often have superb routines with glove puppets.
A feeder cup of highly contrasted materials is helpful to a young child.
You will be interested in following up this section if results in the Summary Chart suggest the learner is functioning at the level of Localising objects and events in the world. You will probably have found Consistent responses to objects which are of low contrast.
In games such as ball rolling, catching, batting of objects use materials which vary in contrast. If successful with one set, the amount of contrast can be reduced or the size of the object reduced. If this becomes successful, then both size and contrast may be reduced.
Also refer to the general comments on use of contrast set out earlier in this section.
Dark adaptation:Difficulties experienced with low contrast will often be associated with the learner having problems negotiating dimly lit rooms (not dark rooms, we all have difficulty navigating around a dark room). If this appears quite suddenly, you should have him referred to an ophthalmologist.
You will be interested in following up this section if results in the Summary Chart suggest the learner is functioning at the level of Recognising objects and events in the world. You will probably have found Consistent responses to objects which are low contrasted.
Although we do not endorse the view that says every mealtime should be turned into a work session, try to reconcile this with the fact that every mealtime can be a wonderful learning experience. Additional 'tasks' should only be added on occasion. These are best done in the form of a game. By paying attention to the kind of cues afforded to the learner, you also avoid the problem of visual information on food and drink being taken for granted. Using good contrast between table top, plates and food items helps make food more interesting and more visible. Visual search can be enhanced by playing an occasional hide-and-seek game using cup, spoon or plate. Rather than making this a chore for the learner, be prepared to boost chances of discovery by tapping on the spoon or plate.
If not immediately successful in locating the object by vision, give him some other form of sound, smell, taste or tactile (texture) cue. Be prepared to use any knowledge gained in this way to confirm or add to that which is found in non-visual sections of Chapter 6.
Finding the familiar
Presentation can be made more personal by including the learner's name - although he may be unable to read, the attraction may well remain. To increase enjoyment a specific symbol of high contrast may appear consistently across many different formats. This encourages searching and scanning across pictures exploring and finding the familiar within unfamiliar surroundings. Specific things to be searched for could be changed each day. One day it could be a search for all of the squares, another the biggest, yet another the one that is different and so on.
This promotes a transition from Recognising to Understanding (compare same/different; large/small; and other variations).
Contrast with tactile properties
Use tactile qualities to reinforce visual information offered with materials of high contrast such as pictures or symbols. Attach to the background materials such as coloured cardboard shapes, stickers, buttons, shiny lids (it is usually best to avoid the use of sandpaper). Texture can be added to different thicknesses of line drawings by sewing over lines with thread. Or reverse the paper using a sewing machine without thread to prick holes along the lines. Another possibility is to daub clear glue along line surfaces. For tactile cues it is easier for the learner to trace broken or corrugated lines than unbroken lines - change is easier to detect).
Use of computers2
Some programs are helpful in rapidly providing an individual profile of optimum colour contrast between foreground and background. Settings can be adjusted without any fuss. The resulting optimum contrasts can then be used for foreground and background card paper.
You will be interested in following up this section if results in the Summary Chart suggest the learner is functioning at the level of Understanding objects and events in the world. You will probably have found Consistent responses to objects which are of low contrast.
Even though the learner may be competent at placing objects into containers, stacking and nesting, it is quite a cognitive leap to the understanding of concepts such as same and different. But these abilities are involved in sorting and matching. A couple of ways of improving sorting are first to have the learner practice stacking identical plastic plates. Then do the same with nesting plastic cups. Try to use materials that are highly contrasted. If successful, place one single plate and a single glass on the table (you might want to glue these in position). Give the learner an identical plate or cup and help locate the matching object, placing it on top. Eventually she will learn to keep together two plates and cups. Once this is successful, other objects can be introduced in the same way.
It is also helpful to use different containers as a sorting cue. Suppose the aim is to get the learner to sort items into two piles. Select two sorts of objects that are quite different in size, shape, texture and colour for contrast. To make this easier, use two different sized containers. For example use a metal box or wicker basket for one type of object and a long narrow cardboard box for the other. It is best if each container will only take one and not the other type of object. Once she is able to sort in this manner then try with two containers of similar size or similar material.
As with most children, brightly coloured purses or handbags represent useful objects to explore by opening them and searching.
For the learner who has severe physical disability, eye-pointing may be used to establish a means of communication. Use high contrast objects against background. Only when the learner is very successful in eye pointing to objects should you progress to large changes in position of food and drink materials. If successful, this will offer a lead-in to more abstract forms of eye-pointing as a means of communication (such as eye coding).
Teaching of specific activities can often result in a great deal of success, but only in those activities with little transfer beyond. Rolling balls may be helpful to incorporate an element of problem solving. Use rolling balls of different colours. After several presentations of the same ball rolling backwards and forwards and watching visual tracking, a different colour of ball can emerge from say under a cloth, behind a short "wall" or through a tunnel.
Use of computers5
The same control over foreground and background colours is available on a number of computers. Sometimes this control takes place in the hardware (the machine itself), while at other times it is controlled through the software. If uncertain ask for help from a computer buff and refer to Appendix II for information on useful resources.
Parents and educators usually know whether a young person responds to illustrations or pictures. Those that are brightly coloured will have most appeal, attracting the eye more easily. Sometimes, however, knowing that a learner has visual impairment puts people off from giving him or her visual material. If you already know that pictures evoke a response or if your student can see at least medium-sized objects with good contrast, then it is worthwhile including coloured illustrations as part of your teaching materials.
Bright colours attract the eye and give pleasure. However, contrary to what one might expect, the colour and size of a picture may not necessarily make it easier to perceive than the black and white letters used for eye tests. An interesting study of ability in children with refractive errors to "see" pictures, showed that this ability was much poorer than might have been expected from their distance visual acuity for black-on-white Snellen letters (Sonksen, 1987). This is explained by the fact that the letters are images with clear-cut form and maximal contrast, foreground to background, with variation only in the size of letter. Coloured pictures have a combination of factors which make them more complex. They vary in contrast between subject and background, there may be overlap of one image on another and they may be "busy" with many items in one picture. How can we then explain how learners who do not have vision for great detail, recognise pictures? Sonksen explains it as a combination of remembering visual clues such as colour and overall size and shape along with remembering what they have been told about the picture or the name of an object in the picture. Even although the learner may not perceive an illustration with the same clarity for detail as we do, it does not detract from the pleasure and feeling of achievement for the learner who points or names correctly.