University of Edinburgh
 

Tactile Graphics

CHAPTER FOUR: Questions of memory and strategy

4.1 The influence of memory

Any perception based on tactual input has two components - a sensory component and a memory component. Even if other modes of sensory input are excluded, the haptic sensations arriving at the central nervous system only partly account for what is perceived, because these sensations are integrated with the subject's memory of previous experience, (most powerfully with previous tactual experience) and are then attended to, identified, evaluated and responded to in the light of this experience. It follows that variations in previous experience may he expected to modify the perception. it also follows that any outside influence or supplementary information which may alter the subject's expectations will also have a marked effect on the perception.

To offer a simple explanation of this: Within the total darkness of one's own bedroom, stretching out one's hand may cause a fingertip to collide with, say, the top of an alarm clock on a bedside table. In these familiar surroundings which signal a specific 'expected environment', well-known and precisely located objects can be identified or predicted with a surety which cannot be explained solely on the basis of the meagre sensations of that brief touch. One has a strong perception, not only of the actual objects touched, but a knowledge of the environment constructed largely from a memory of surrounding familiar objects and furniture.

Contrast, then, the experience of Sammy Mountjoy, the central character from William Golding's novel. 'Free Fall'. (Golding1959 pp 166ff). He is blindfolded and imprisoned in a small cell. The last words of his inquisitor, Halde, which remain on his mind are 'If necessary, I will kill you.' In this frame of mind, his ceil becomes a possible anteroom to a torture chamber and a moist, slimy lump on the cell floor is identified as a piece of decaying human flesh, possibly from a previous victim. It is only when he is released from his place of confinement that a backward look reveals that the cell is merely a hastily cleared broom cupboard and the 'human flesh' nothing more sinister than a wash leather inadvertently left behind. His mind had created bizarre Identities for the objects he had felt in the darkness.

This account. although fictional, is a valid statement of experience, and these two lighthearted examples, the first homely and familiar, and the other bizarre and threatening. offer a clue to the range of possibilities for a blind person reading a tactile display. Sensations received through the fingers at the time of reading only partly account for what is perceived, although by careful design what is provided on the page may derive the utmost advantage from what is contributed from memory.

The author carried out simple experiments with blind children from four to six years old in an attempt to evaluate the relative contribution of touch sensors to the identification of familiar objects by artificially restricting the amount of finger contact to the tip of the index finger and the opposing thumb as in the picture. The fingers were held by the experimenter's hand to prevent any perceptible sideways movements, but allow a small freedom of pressure. The objects and contact points are listed in Figure 3 and the results are given. Except for the two slight variations listed, the identifications were unanimous, and for the ball two additional bits of information were offered by some of the children.

Object Contact point Response Further question or action Further response
China cup Bottom of handle where it joins cup Five said "a cup"
one said "a mug"
If "mug", allowed to feel bottom of vessel "Oh no, it's a cup!"
Ballpoint pen Middle of barrel Four said "a biro" one said "a pencil If "pencil" asked what pencil is made of and then "is this wood?" "No it's plastic. It must be a biro"
Soft ball of tennis size Surface Always "a ball" Always "a Ball" All said " a soft ball". One also said "it's a sponge ball. An old one, because the paint is flaking away".
Ballpoint pen Cap and clip Always "a biro" Always "a biro"  

Fig 3: Identifications made by six blind children aged 4-6 from a restricted contact with everyday objects.

Plainly, complete identification of the items given would not be possible from the restricted contact allowed without considerable previous handling experience of the objects, or to put it another way, it would be impossible to construct a perception of these objects from the available sensations alone.

Similar results are found with tactile diagrams and pictures and the result will vary according to the richness of the subject's previous experience and the extent to which this is relevant to the picture or can be brought to bear upon the picture. A variety of responses are found which are often so specific to the subject matter that no useful purpose would be served by quoting individual examples, but to attempt some systematisation of these, consider three possible cases:

(a) Diagram not met before by subject, nor any similar diagram.

(b) Diagram not met before, but similar or related diagram has been used previously.

(c) Diagram or an exact copy met before.

The normal results from these three possible situations appear to be as follows:

(a) The subject will understand the diagram if it bears some similarity to objects from his/her real world and this similarity is sufficiently obvious to the touch. The wider the subject's handling experience, particularly if this has included tactile pictures, the more proficient is he/she likely to be.

b) Similar results to case (a) with greater chance of success the more obvious the similarities are. Any clues from braille titles, tape or oral instruction will enhance the effect of the diagram.

(c) Recognition can be instantaneous from very slight contact. There is frequently no need for full scanning of the picture. Serial reading of the shapes as in reading lines of braille is not required.

Very frequently an almost instantaneous identification can result from contact with a tactile picture. It needs to be emphasised that such a quickness of identification is only possible if the blind person is prepared to risk what Millar (1974) describes as 'a trade-off between speed and accuracy'. The subject relies on the picture (or object) not possessing bizarre and unpredictable distortions in the spaces between the finger contacts. With one of the familiar objects described in the simple experiments above, the subject is making the reasonable judgement that there is no surrealist embellishment attached to the cup handle, for example. This would be very unlikely in everyday life, although theoretically and practically possible.

This behaviour also accords with some of the postulates of general information theory in which expected sequencing or juxtaposing of elements discovered can help to narrow down the number of possibilities to be eliminated, and thus reduce the information processing load (Attneave, 1959, Chapt 2), as can the possibility of aggregating the information into easily remembered groups or patterns, which also assists memory. (Ibid, p.82).

The operation of the mind in this sort of context was summed up in a quotation from Maximus Tyrius, quoted by Gombrich (1960, p 170):

"The mind, having received of sense a small beginning of remembrance, runneth on infinitely, remembring all what is to be remembred." -Maximus Tyrius 'Philosophumena'

When we are presented with a mass of sensory information which at first seems to be formless we try to discover some pattern or rhythm in it; to make some sort of sense out of it. This is something we try to do from birth. Our attempts are very diverse, and the school of gestalt psychology, is founded upon them. In addition, visual an often makes use of this behaviour for successful communication of creative ideas. These may range from cartoons and caricatures to sparse line drawing styles or tricks of colour and shading. To a large extent they are part of the very stuff of visual art which is admirably described by Gombrich in his book entitled 'Art and Illusion' (Gombrich, 1960, Chapt 7).

With tactile pictures, as with visual art, the reader's memory and imagination can be stimulated in such a way that they can be encouraged to run ahead. and even perceive things that are not really present at all. In this way tactile communication can be enriched. These phenomena will be referred to in relation to specific educational diagrams and pictures later in this book.  

4.2 Short-term memory

These comments on memory so far refer entirely to what is known as 'long-term memory', namely the memory store which is retained, and can be reflected upon and brought into use as required. There is also a phenomenon known as 'short-term memory' which acts while manipulations and explorations are actually in process and which enables individual sensations or sensation arrays to be integrated and interpreted without appearing to register in any permanent sense in the brain.

Long-term storage may in fact generally involve a strengthening of the memory trace by repetition of the event, either directly or by mental 'rehearsal' after it has occurred. Millar (1974) found that short-term memory impressions decayed both after an unfilled delay of time and under the influence of attention-demanding distractors, but that there was no statistical interaction between these two effects.

Her data appeared to support the hypothesis of Gilson and Baddeley (1969) of 'a tactile impression which delay degrades or makes less accessible and a longer term process requiring capacity with which distractors interfere'. (Millar, 1974, p 262)

This short-term memory is vitally important for the environmental understanding and tactual learning of blind people. Hinton (1984, p 21) drew attention to the problem which blind observers have in bringing overall coherence to a series of tactual observations which are, from the nature of their method of collection, fragmented. Even within the bounds of a single page there is a problem for a blind reader in relating diagram components to each other; in drawing them together to make a recognisable form or 'gestalt'. It seems to be the short-term memory which holds the available information until this gestalt emerges from the welter of incoming touch sensations. This process is necessary whether the features spread beyond a hand's-breadth so that they have to be sampled successively, or whether they can be held simultaneously, but are detected by separate nerve endings.

4.3 Speed and accuracy in scanning

In much the same way that rapid judgements of the identification of concrete objects can be made by a spatially restricted touch, judgements can be made rapidly from sequences of sensation in the scanning of objects and diagrams. Often at even greater speed in fact, because of the richer array of sensations collected.

Millar's comments (Millar, 1974) about the trade-off between speed and accuracy still apply here of course. No blind person could keep up with the pace of modern life and education without being prepared to risk occasional errors from snap judgements, or to quote Millar, (1975): 'Sacrificing some accuracy for speed is more economical when dealing permanently with relatively slow inputs' .

Education must provide the person with the skills and experience to be able to consider a sufficiently wide selection of alternatives for each life situation, and the maturity of judgement to decide upon the necessary limits of this selection. Part of early education should provide blind children with the security and lack of embarrassment from possibilities of destructive assessment by teachers. This would encourage the child to advance reasonable postulates on the basis of the available evidence, and then take steps to collect additional specific evidence to allow them to eliminate some of the possibilities.

Classroom experiences lead the writer to believe that far too often, because of their experiences of pressure from unskilled teachers or over-ambitious or ill informed parents, blind children can be afraid to put forward a suggestion because of the fear that they may 'make a mistake', and thereby earn condemnation. Because of this inhibiting fear of being put into a situation where they appear to be unintelligent or stupid they are not willing to 'have a go'. Many learning situations can thus unnecessarily remain entirely passive and didactic if the opportunity to make an attempt or to 'put up a suggestion as a basis for working' is not provided. It is vital that teachers should find ways of breaking out of this vicious cycle of inhibition and resulting passivity, and that parent counselling makes the parents of blind children aware of this problem at an early stage.

4.4 Using Yngstrom's methods with 4-6 year-olds

Arne Yngstrom is a Swedish teacher with a particular interest in orienteering as a sport and a recreational activity. In recent years he has devoted much time to finding ways in which young people who are blind can be taught to take part in orienteering activities. To do this, of course, they need to learn to relate their personal mobility and space awareness concepts to some type of map.

Yngstrom's teaching methods follow a carefully thought out sequence from tracing round the fingers of the child's own hand on German Film, and on to relating simple table-top models to a drawn plan, before small scale navigation through an obstacle course with the aid of a map, and so on. (Tatham and Dodds, 1988, p 91-108) The various stages develop the child's understanding of a 'map' as a representation of a reality which can be separately experienced.

There is no doubt that Yngstrom's teaching methods with young children are soundly compiled and contain much that is of value to young children. They have also been an inspration to many teachers and a stimulus to researchers. This is not to say that his published lessons are in any way complete as a line of approach with all blind children in the target age group. In fact very few blind children, and those only with a particular background of parenting and experience. can begin the Yngstrom lessons without preparatory training in manipulative and control skills, and Yngstrom pre-supposes a certain minimum of basic mobility skill. The children should have some knowledge of parts of the body, and the ability to find and recognise these in other people as well as themselves. They also ought to have a little experience with simple geometric shapes, and the recognition of everyday objects by touch.

If pupils are to trace and draw on German Film in the way that Yngstrom describes they must first learn to hold and manipulate a pen. This skill alone is harder to acquire for a blind child, who hasn't the ability to observe the teacher's pen grip while attempting to imitate it as a fully-sighted child can. It is a matter of feeling the grip; retaining the model in memory; and then attempting to copy it. Careful teaching is required to achieve this, and since the pen would not normally be used for writing there would not be so many opportunities to practice. Yet there is great value in drawing activity for the blind child, for the need to draw causes more careful tactile observation of real objects and also helps the pupil to understand tactile diagrams which are later presented for teaching purposes. Besides which, every blind child I know who has tried to draw has found great fun in doing it!

In continuing the kind of development that Yngstrom's methods foster, it is also necessary to be able to trace round a template accurately by following its shape closely. It is necessary to make a consistent and distinctly raised line on the film by holding the pen upright and controlling the pressure on the mat. Too much pressure and the pen digs into the mat; too little pressure and no tactile line is left behind. In this connection it should be mentioned that during work with blind children between 4.5yrs and 6yrs old the writer observed that these children appeared not to show a preference for either right or left hand as early as fully-sighted children in this age group, and this lack of a favoured hand could hinder the development of a firm and controllable pen grip.

In the absence of sight it is vital that children get plenty of practice in the sensorimotor or kinaesthetic sequence experiences which result from following particular simple shapes. This can best be done in the early stages by laying aside the pen, and drawing round templates or objects with the index finger. The shape should be followed repeatedly in this way before any attempt is made to draw round the shape on German Film. Experience in relating an outline on film to the concrete three-dimensional shape should also be provided, and this is something which Yngstrom emphasises in his publications. (Ibid, p 94) It must he remembered that silhouettes (in conditions of reduced light) and outline representations are very much part of the visual scene, but are not really part of the blind person's normal experience. So if outlines are to be used the correlation of outline to solid object must be learned. In the classroom it is useful to provide a selection of objects of the brick and cocoa tin type and to present them to the pupil in various orientations, asking the two-dimensional shape from a given viewpoint. Many five year-olds do this with ease, but some can only make the necessary leap of imagination after careful teaching.

4.5 Memory and experience

To recapitulate the concerns of this chapter:
What is contributed from the pupil's memory forms a vital part of what is perceived from a tactile picture, or indeed from anything handled by a blind person. The reservoir of tactual experience on which that person can draw will be enhanced by wide-ranging touch experience of all kinds (aided by what is experienced by the other senses). This needs to be begun in the child's earliest years if possible, and can be further strengthened by imaginative and carefully presented educational experiences at school. Yngstrom's methods (described above) are a good example of how part of this experience can be offered. Other suitable learning activities are discussed in Chapter 9.

In discussion about tactile diagrams and other spatial concepts the congenitally blind are said to be a particularly disadvantaged group by 'having no visual memory'. The next chapter will discuss the educational implications of congenital blindness and the extent to which this type of statement is now appropriate.

Ron Hinton
First published 1996
ISBN: 0901580775