4.2.1 Conceptual Considerations
In the widest sense the concept of usability is dealing with the interaction of the map-user with the map. If the map is provided for example via Internet, additionally the topic of man-machine-interface has to be taken into consideration.
Therefore, it is vital to keep in mind the psychological processes described in chapter 3.1.
Recognition can be divided into two processes taking place more or less at the same time.
There is the information processing, which can be described as a “bottom-up-process” resulting from a sensory stimulation and the “top-down-“bottom-up-process” of recogni-tion itself, where the retinal images are recognized by being compared with mental categories.
Therefore, the aim of a suitable cartographic product, which should meet the stan-dards of usability, should be a cognitively adequate visualization.
To meet this criterion it also has to distinguish relevant from irrelevant information.
This sounds easier than it is, because the relevance of information differs from audi-ence to audiaudi-ence.
Certain interests and activities identify these audiences. But unfortunately, even spe-cific audiences cannot easily be generalized, because they consist of individuals with different dispositions and preferences.
An example for this is the target audience for a cartographic chart representing the limits of the bodies of water in the Southern Ocean.
At the first glance the audience “scientists with an interest in the Antarctic region”
seems to be quite homogeneous. But after further investigation it becomes clear that it is not. The scientists come from different countries with different cultures. Although all these persons can be counted to the same audience with one special interest, they have different dispositions and preferences. The phenomenon of heterogeneity within a target audience is very much supported by the trend of globalization. The quick availability of information concerning a special interest via internet is a fact that has to be taken into consideration. Therefore, one cannot assume the audience – although being very small – to be homogeneous.
Along with interests comes the aspect of attention. As a matter of fact our attention is guided by our interest and it is supported by the design of the sign-vehicle (e.g. clo-sure, contrast and figure-ground-segregation in chapter 3.1.1.2.1).
A usable cartographic chart should make it easy for the map-user to more or less
“automatically” identify the information he seeks.
Hence, the data has to be provided in a manner that supports explorative processes.
Nevertheless, it must not be forgotten that the use of a map still remains to be an individual activity.
In chapter 3.1.1 the psychological bases of perception and information processing have been discussed. The socio-cultural dimensions of the map-use have been out-lined in chapter 3.1.2.
The socio-cultural environment influences the preferences and the evaluations of the individual and most importantly directs the attention of the map-user to certain fea-tures.
From this one can derive at least four topics that are important for producing a use-able map.
Firstly, the chosen representation has to meet the limitation and the functioning of human perception and information processing.
Secondly, the map must be tailored to the task it will be used for.
Thirdly, the whole concept of the map must incorporate the technology being used.
One must consider the “map-interface”. Modern technology can facilitate man-map-interaction a lot.
Last but not least, the map-designer must take into consideration the social and or-ganizational environment of the potential map-user. This topic becomes very impor-tant when designing special-purpose cartographic products like the one to be de-signed in the practical part of this thesis. It deals with topics like the question, which kinds of computer hard- and software are been used by the target audience.
4.2.2 Practical Considerations
As pointed out during the introduction of this thesis the map is and can only be for a purely scientific purpose. The limits that are drawn will in no way have a legal effect on any party of the Antarctic Treaty. They only will be a suggestion of how to visual-ize potential limits in the Southern Ocean for scientific needs.
In contrast to a common international nautical chart the audience in the first place will not be mariners but scientists.
The cartographic product will – according to its purpose – emphasize the limits of the different bodies of water resulting from the bathymetric data, parallels, meridians and rhumb lines.
The limits will be visualized as red lines. This choice can be deduced from the proc-esses that happen during the map-user’s perception and interpretation of the carto-graphic product.
These processes are described in chapter 3.1.
On the private/perceptual level (chapter 3.1.1), which describes what is perceived, the following processes can be identified.
Red as a signal color guides the viewer’s attention directly to the relevant topic of the map. He is not distracted by less important features like the outline of Antarctica or the available information about the bathymetry of the seafloor.
The lines are identified as figures, because of their closure. The huge contrast be-tween blue as the background color and red supports the discrimination of figure and ground – the figure-ground-segregation (chapter 3.1.1.2.1). So, the recognized object is classified as an area.
This point represents the interface between the private/perceptual and the pub-lic/social level.
The public/social level deals (chapter 3.1.2) with the question of how the perceived object is interpreted. The socio-cultural background of the viewer plays a very impor-tant role here. This is the reason why there has to be an analysis of the relevant target audience.
If it is known how this audience normally visualizes certain objects, one could use these known concepts to support the understanding. This procedure is part of a con-cept that enhances usability.
Familiar visualizations help to avoid misinterpretations. Following the holistic ap-proach to communication proposed in chapter 4.1.2 one could say that in such a case the reality of the cartographer and the reality of the map-user are nearly con-gruent with each other.
The process beginning with the perception of the sign-vehicle, which is the figure out-lined by the red lines, and ending with the interpretation that this figure represents a
certain body of water in the Southern Ocean as the referent can be depicted by a semiotic triangle.
This triangle visualizes the relationship between the sign-vehicle, how it is interpreted (interpretant) and what it refers to (referent).
Unfortunately, in case of nautical charts the relevant audience is not used to visualize limits as red lines. It is common but not conventional to visualize limits as dotted black lines, if they are represented at all.
But in the context of a nautical chart, names of certain areas in conjunction with red lines outlining these areas, misinterpretations are not likely to occur.
So using red lines instead of black dotted ones – which would be “best practice” – is a result of scientific analysis and research. This decision is based on a theoretical foundation having its roots in psychology, sociology, semiotics and communication theory. This means that it results from an interdisciplinary scientific approach.