Language of Maps for Blind and Partially Sighted People: Expressive and Perceptive Skills
Cartographers create maps to be read by other people who may know nothing about cartography. The cartographer uses expressive conventions that must be learned and interpreted by the user, who in turn employs receptive skills and techniques. Both expressive and receptive skills are involved in the fascinating transfer of symbolic information from one person to another.
In the world of blind and partially sighted people, these expressive and receptive skills are different in many ways from those used by the sighted. Tactile cartographers must learn numerous guidelines for the development of tactile maps and charts, bearing in mind that the tactile sense is restrictive compared to sight. Print maps allow the use of color, variations in fonts and print sizes, overlapping layers of symbols, and other visual features. The tactile map-maker uses none of these, instead using tools and conventions unknown to most print cartographers.
And how does the learner who is blind interpret maps and come to understand that a map is a set of symbols for a real place? How does the learner with low vision learn that she may use color to infer real meaning with regard to maps? To teach the receptive side of mapping with blind or low-vision readers requires training, experience, and specific techniques that are discussed here.
KeywordsCartography Conventions Interpretation Map skills Tactile Teaching
Maps are created by people who are skilled in the cartographic arts, to be read by other people who may know nothing about cartography. The cartographer uses a set of expressive conventions that must be learned and interpreted by the user who engages receptive skills and techniques. Both expressive and receptive skills play strong roles in the fascinating transfer of symbolic and cartographic information from one person to another.
In the world of blind and partially sighted people, these expressive and receptive skills are different in many ways from those used by the sighted. On the expressive side, tactile cartographers must learn numerous guidelines for the development of tactile maps and charts; some variables include production media, quality of design, and Braille notation. While print maps allow the use of color, standard map symbols, manipulation of text to follow rivers or denote the size of cities, and other visual features, tactile map-makers use none of these. Their tools and conventions are unknown to most print cartographers, and they must keep a fine balance between enough information and too much information.
Regarding receptive factors, how does the learner who is blind interpret maps? How does she come to understand that the map is a set of symbols for a real place? How does the learner with low vision learn that she may use color to infer real meaning with regard to maps? How may they each come to understand concepts such as scale or longitude and latitude? To teach interpretive map skills to learners with visual impairment or blindness requires training, experience, and an energetic spirit.
This article will detail some of the considerations for the creation (expressive side) and interpretation (receptive side) of maps when users are blind or partially sighted.
Expressive Considerations for Tactual Readers
The entry point for understanding tactual learning is to consider how the sense of touch differs from the sense of sight and what the differences entail for the map designer and the map user. With an appreciation of these differences, a thoughtful designer can move past the common assumptions or misconceptions about blind readers and toward a meaningful communication based in a nontypical sensory mode.
While the sense of sight is considered a “distance sense,” meaning it detects objects at a distance, the sense of touch depends on proximity or direct contact. In contrast to the field of view allowed with typical vision, the field of view for touch is defined by what the hands contact. The number of receptors for touch present in the skin is quite small compared with the quantity of visual receptors; likewise the area in the brain devoted to the haptic (tactual) process is small compared with that given to the visual process. These factors dictate that the perception of graphic information by touch occurs sequentially. It is pieced together through a series of tactual impressions. What can be gained through the sense of sight in an instant must be taken in piece by piece through the sense of touch and assembled into a meaningful whole.
A consequence of this difference for the design of maps is that the palette of usable conventions for encoding information is restricted. Consider the variety of ways in which printed maps typically present different kinds or levels of information: through colors, shading, line types, symbols, type fonts, variations in type size and orientation, and overlapping images, among others. Of these options, the palette for tactual readability, as suggested by research, includes only a limited degree of shading (in the form of raised textures), line types, and point symbols. Additionally, the tactile map designer must be careful not to overload the image with too many variations in line and texture lest the task of decoding becomes too laborious.
Research on legibility of tactile elements in graphics has established requirements for the size and spacing of point, line, and areal symbols in order for them to be perceived and recognized by touch. For example, two graphic elements of information require at least 1/8″ (3.5 mm) of separation to be recognized as different. Likewise, polygonal shapes need individual sides of 1/2″ (14 mm) or longer to be recognizable. Similar guidelines dictate the size and shape of point symbols and lines for tactual readability; these are based on the size and sensitivity of the average reader’s fingertips, among other factors.
Approximately one-third of the symbols in each group shown here (denoted by star symbols) proved to be highly distinguishable by touch. Among the areal symbols, certain stripe patterns were viewed as discriminable while similar patterns with different spacing were not. Among the lines and point symbols, many items that are readily discriminated by sight were not easy to discern from one another through touch. Many are tested, but few are chosen, so to say, when it comes to selecting symbols that can reliably be identified by the tactual sense. These are some indications of the restrictive nature of tactual perception compared with sight.
Within the palette of usable line, point, and areal symbols, some are “go-to” symbols, while others are of limited application. The often-stated rule is that tactually prominent symbols should be used for the most important features of the tactile map or diagram. As an example, a campus map made for a student might employ the highest level of relief to show the student’s dorm or the building where most of her classes will be held; this becomes the focal point of the map from which other places take their relative positions. Likewise in the case of a political map, this rule suggests it would not be appropriate to use a strong texture to denote the ocean if the land is meant to be the focus.
In actual practice, the rule regarding tactual prominence is treated more as a guideline, depending on the production medium used for the particular map, for reasons discussed below.
Processes and Materials
Tactile maps are produced in a great variety of media. Some are built up through collage, using cardboard, string, fabrics, and other common materials; some are embossed on paper or plastic sheets, either by hand or mechanically; still others are output on raised-ink printers. Sometimes a single copy is made and given to a reader; in other cases the original copy becomes a master from which numerous molded (thermoformed) copies are made.
Each medium offers its own advantages and disadvantages for ease of production, cost, tactual distinctiveness, and usability with different populations. These differences have had a wide impact on efforts to standardize tactile map creation and help to explain why, when it comes to any particular map design, the rules are often made to be broken.
In between the more sculptural processes and the simple embossing techniques discussed are other production methods; each offers different advantages and drawbacks in ease, cost, and usefulness for a given application. While a few large producers, such as the American Printing House for the Blind and the National Braille Press in the United States and government-sponsored agencies in other countries, may employ all the available processes, the typical small producer of tactile materials will use one method, possibly with some unique handcrafted additions.
The expressive side of tactile mapping is thus anything but standardized. Every map designer is relatively gifted or restricted by the production medium and what it can meaningfully convey, as well as by the designer’s skill in using the palette of symbols. A thoughtful designer understands that a set of symbols known to be tactually discernible in one medium may not have the same properties in a different medium, because of differences in relief, profile, texture, or sharpness, and chooses among them accordingly.
The second practice is to distort aspects of an image, either to make it more tactually readable or to accommodate needed symbols and labels. Thus the designer may slightly enlarge Luxembourg on a map of Europe to give the reader a tactually discernible area to perceive.
A Difference in Perspective
A final consideration related to the expressive aspect of map design, and one that leads to a discussion of the receptive side, is that print maps are made with a sighted audience in mind. In general, maps are readily comprehended by sight because they give an image or translation of a spatial layout that corresponds with what a sighted person would see, typically from above. The blind person does not have an aerial view. Nevertheless the blind reader must learn to interpret maps presented in this way. The blind reader performs a further translation in order to relate the view from the vertical perspective to the physical world, which is encountered sequentially and only on the horizontal plane.
Schools consider it important for all students, sighted or blind, to have experience and skill in reading maps. While GPS and advancing technologies hold promise for helping blind users navigate from one location to another, map reading promotes interpretation, spatial understanding, directionality, and other skills, and it is an indispensable aid in geography, history, social studies, and related work. Like their sighted peers, blind students show different attitudes toward maps, ranging from enthusiasm to indifference. They also need practice to acquire their skills. We should bear in mind, however, that maps are always in the “native tongue” of sighted learners, more or less, while for blind persons, they are more like a “second language.”
Receptive Considerations for Tactile Maps
Because sighted children in modern societies are exposed to pictures from the earliest age, there is seldom any need for specific instruction to help them relate images to corresponding objects in the outer world. While young students are often given practice in making simple maps, it is always assumed that sighted students are familiar with the basic purposes of maps and that this knowledge is absorbed through early exposure, not only to maps but to pictures in general.
In the absence of near-constant exposure to imagery, blind learners have far fewer opportunities to develop a natural connection between images and their corresponding objects or locations in the physical world. Instruction in map use for blind students, therefore, typically begins with the concept that “maps represent real places.” This concept, regarded more or less as a given for sighted students, is a necessary starting point when teaching blind students how maps are used.
Using critical concept vocabulary (i.e., on/off, toward/away, along/across, near/far), student describes the relationship of self and a chair in various placements. Some placements are arranged by the teacher, others by the student as instructed by the teacher.
Student describes relationship of self and a rectangular table in various arrangements.
Student describes relationship of self and a circular table in various arrangements.
Student works with arrangements of tables and chairs together.
Student works with large symbols (squares, circles, and triangles) representing tables and chairs in various arrangements.
All the stages involve creating maps after an examination of the environment and arranging the environment after an examination of maps. The physical movement in this interplay helps students to be active agents in their learning and builds a kinesthetic feeling for the symbolic terrain of maps.
A common misconception about blind persons is that their sense of touch is highly enhanced as a result of their lack of sight. This assumption has probably led to untold numbers of missed learning opportunities, because the faculty of touch must be cultivated and integrated with other faculties if it is to reach its full potential. Specific hand skills considered essential to tactual learning include line tracking, shape and symbol discrimination, and scanning. In the past two decades, recognition of the need for specific interventions to promote hand skills has brought many new products to the market, most of which are also linked with early literacy, play, or puzzle-solving. The hope among developers is that a generation of blind learners will grow up with the ability to use their hands in active, purposeful ways to read tactile material.
With a solid foundation of hand skills, vocabulary, and positional concepts, students can progress to the specific skills needed for practical map use, such as directionality and scale. These can be taught to blind learners in the same way as to sighted students, provided the materials and examples used are given in an accessible format.
Expressive Considerations for Low-Vision Readers
Sans serif fonts
Sixty-nine specific colors, no red except International Dateline and Greenwich Mean Time
Colors that can provide adequate contrast for both people with visual impairments and those with color perception deficits
No more than three layers of information on any single map, with additional layers added by use of transparent overlays
Labeling features such as names of rivers that follow the curvatures of the waterways, or dots that have white or yellow halos around them for capital cities.
Tools and conventions for use by the student with low vision are more obvious than those used by the student with blindness. Most people will recognize that large print is often a useful option. But large print alone does very little to help the student with low vision decode a map. Research has shown that color, enhanced spacing, increased letter height (and sometimes width), and clean fonts without serifs, when combined together as “enhanced formatting,” often make a map more useful, more readable, and more enjoyable to use (Evans and Kitchel 2002). The American Printing House for the Blind, an agency charged by the United States government to design and produce educational materials for students with low vision and blindness, has developed 69 different guidelines for development of its maps. When used, these guidelines have been shown to promote better usability, improved decoding by users, and greater user enjoyment (Evans and Kitchel 2003).
Use of 18-point font as a basic standard is best. Occasionally, when a map contains many long words, 16-point may be necessary to accommodate all the words. Care must be taken to make sure all the words are necessary.
A wide-bodied, sans serif font is used. The most recommended fonts for use by students with low vision are APHont, Verdana, Tahoma, and Antique Olive. Arial, though a sans serif font, is not recommended because the letters are too close together (Evans and Kitchel 2003).
Generous t-heights and x-heights are helpful to users who have low vision. APHont and Verdana are the sans serif fonts that have the most generous t-heights and x-heights, both 1/8 in. at 18-point font size.
Use of many shades of blue, brown, gold, and black and white in political and thematic maps suits virtually everyone. Even 99% of people with color perception deficits can see these colors. Often other colors are used as well, but when they are, the cartographer uses the VisiBone filter to determine how the maps will look to people with color perception deficits (see Stein 2005). If the politically or thematically identified areas are not distinct from one another, revisions should be made until they are. Because of certain eye conditions that reduce sensitivity to the color red, block it entirely; red is only used for Greenwich Mean Time and the International Date Line.
The spacing of letters and elements on a map can make it more readable, or altogether unreadable. Space between letters and space between lines of text are the most important. Fonts should be chosen based upon generous spaces between letters, which is known as kerning. APHont and Verdana are the best English language fonts because of their generous kerning. Spacing between lines of text should be 1.25 spaces (Evans and Kitchel 2003).
Continuous text, such as that found in legends, instructions, and descriptions, should always be aligned on the left, no indentations. There should not be alignment on the right since it causes large spaces to occur between words. One must think of the student who uses a magnifier to read her map. If there are indents or large spaces between words, she may assume she is at the end of the line of text, or she may miss the opening line of the text because it is indented beyond the field of the magnifier (Evans and Kitchel 2003).
The most frequently used labeling features include names of rivers that follow bends in the waterways.
Icons used for resource maps must be 36 pixels × 36 pixels; this is the smallest an icon can be and still be read by a person with low vision who uses a magnifier.
Most lines such as latitude and longitude are 1.5 points in width at the very least.
No more than three layers of information should be included on a map. For example, political boundaries, capital cities, and primary waterways along with their names would constitute three layers. If more information is needed, a clear overlay that contains the additional information is the best choice so the additional information may be separated out if necessary.
Receptive Factors for Low-Vision Readers
Just as it is with people of typical vision, users with low vision must be taught what map symbols are and what they mean. They need practice with the maps and the various magnifying devices that are often used. Receptive and decoding skills are sometimes slow to develop when the user has a limited field of vision. Users with low vision are taught a methodical way to scan a map as they move from left to right across it and down from top to bottom. It is often difficult for the user to piece together all the little bits of information he or she has gleaned to understand the overall look and concept embodied in a particular map. However, over time, his/her visual memory is able to store more information, and he becomes better at decoding the information and putting it together as a single image. Experience and reports from hundreds of users of maps that conform to enhanced format guidelines have shown that users can more easily decode, use, and enjoy them.
It is sometimes astonishing the facility that even young students with visual impairments can develop. With skillful teachers and carefully constructed materials, persons with blindness and visual impairments can develop the receptive abilities they need to read and interpret maps. The authors urge all persons who wish to expand access to maps for this audience to visit www.aph.org/ to learn the rules and conventions for tactile and enhanced print maps.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Evans, W., & Kitchel, E. (2002). Design features used in maps for students with low vision. Louisville: American Printing House for the Blind.Google Scholar
- Evans, W., & Kitchel, E. (2003). Survey of useful features of maps used by 200 students with low vision. Louisville: American Printing House for the Blind.Google Scholar
- Franks, F., & Cozen, C. K. (1982). Instructional guide for maps represent real places: Map study I. Louisville: American Printing House for the Blind.Google Scholar
- Nolan, C., & Morris, J. (1963). Tactual symbols for the blind (Final report OVR-RD-587). Louisville: American Printing House for the Blind.Google Scholar
- Stein, R. (2005). Color deficient vision. Retrieved from http://www.visibone.com/colorblind/