Spatial Data Visualizations
The spatial data visualizations that students will typically see in social studies, or that they can use for inquiry in social studies, serve six basic functions: They show us locations, allow us to see patterns, distribution, movements, or relationships, or help us make comparisons. Most of the spatial data visualizations students will encounter in social studies are maps, but it's important to recognize that not all maps are the same, and not every map fulfills the same function. In addition, some of the spatial data visualizations students might encounter in social studies are not traditional geographic maps at all -- they represent humans' efforts to map out stars and planets, caverns and tunnels, or parts of the human body. Regardless, all of them use "data" to visualize a space that humans have found worthy of exploration or conquest, or that they know is important to our survival or growth.
LocationThe one function that all spatial data visualizations share is showing location. This is as true of maps as it is of visualizations depicting the stars or the human body. Regardless, it's important to remember that they are all human creations. When making maps, for example, cartographers can choose to include different structural features, and they make choices about scale, projection, symbol systems, and color schemes, and what to include and what to leave out. Regardless of the form, it's important to pay attention to all of its features and to remember that visualizations have authors with their own intentions and biases, as well as a knowledge base and perspective limited by the time and place in which they lived.
Patterns
Historians use maps such as choropleth maps, connection maps, and dot maps to visualize spatial patterns that cannot be seen with the naked eye. They can use such visualizations to help them answer questions about the past, or to provide evidence when they are making arguments or providing explanations about the past. For example, in their influential study Salem Possessed: The Social Origins of Witchcraft (1974), Paul Boyer and Steve Nissenbaum made significant use of a map of Salem Village in 1692, which showed the locations of virtually all the households in Salem Village. Boyer and Nissenbaum plotted the locations of the accusers and the accused in the Village, and used the map to argue that economic difference divided the village geographically into two conflicting groups -- poorer agrarian householders with Puritan sensibilities on the western side of the village versus more prosperous and commercially minded neighbors in the eastern part of the village. According to Boyer and Nissenbaum, the clash led the frustrated westerners to respond by charging the easterners with witchcraft. Salem Possessed succeeded so well in explaining the witchcraft episode in Salem Village that it was not significantly challenged by another scholarly account until the appearance of Mary Beth Norton's innovative and more comprehensive work, In the Devil's Snare, in 2002.
Distribution
Connection maps, dot maps, and flow maps show how data is clustered or spread out in space. As with maps that show patterns, historians and other scholars use them to answer questions about the past, or to provide evidence when they are making arguments or providing explanations. Perhaps the most famous distribution maps in history is John Snow's cholera map.
