Tactile Map Reading

Limitations

The first significant problem is that a tactile map has to be designed to be read by the sense of touch, consequently, the map can only be read by the resolution of tactile apprehension of the fingertips. Although it is possible to sense very small areas with the fingertips (for example, the point of a pen), for a map to be useful, an often quoted general design criteria is that the working area that can be sensed at any one time is the area under a fingertip. Therefore, the resolution of a tactile map is approximately the area under a fingertip, approximately 1 centimeter (cm) by 1 cm. This presents the potential map reader with a significant problem in that the amount of information that he or she can gain from a map is limited to chunks of information of a fingertip in size.

Perhaps a more significant problem than the limitations of the individual area that can be sensed any one time is that these areas are sensed in isolation, as the fingertip sequentially moves from one area to another. With vision it is possible to gather a Gestalt-like overview of a visually read map in its entirety and the relationships between all of the features. However, when reading a tactile map, the map reader has to move his or her fingers over the surface of the map sensing simplified and enlarged features and then has to piece these individual components of information together to generate a holistic overview of the map. If a conventional visual map was rendered tactile, it would be unreadable by the fingertips due the density, clutter, and complexity of information. An analogy to tactile map reading is to imagine that you have to read, integrate, and comprehend all of the features on a map; however, the map is obscured by a layer of paper. You are then only able to view the map using vision through a hole in the paper, which is the size of a fingertip, and by moving this small window around the map. This provides a general idea as to the problems presented by tactile map reading.

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