Communicating with Maps

Communicating with Maps

Though you won’t need to understand the biology of the human brain and visual system, making great maps requires understanding how people perceive visual information. When discussing how people interpret maps, we can frame this discussion in terms of perception, cognition, and behavior.

Perception in map design refers to the reader’s immediate response to map symbology (e.g., instant recognition that symbols are different hues) (Slocum et al. 2009).

Cognition occurs when map readers incorporate that perception into conscious thought, and thus combine it with their own knowledge (Slocum et al. 2009). For example, readers might be able to interpret a weather radar map without its legend due to their previous experience with a similar map, or might incorporate knowledge of a map’s topic into their interpretation of a visual data distribution (e.g., the higher concentration of people aged 65+ shown in some Florida cities makes sense given what I know about retirement communities).

Behavior refers to actions that go beyond just thinking about maps. Considering how design may influence behavior is essential in anticipating the real-world effects your maps may have. The way a map is designed can influence its readers’ actions and decision-making, and these decisions may range from small (e.g., for how many seconds will the reader look at this map?) to great (e.g., will this flood-risk map convince the reader to purchase insurance?).

Figure 1.3.1 From perception to cognition and behavior

Credit: Cary Anderson, Penn State Geography

Another useful way to think about map communication is with the cartography-cubed model (MacEachren 1994). The model MacEachren (1994) proposed focuses on how different maps and visualizations are used. Within this framework, any map can be located within the cube by determining its location along three dimensions: (1) from public to private (with regards to the map audience), (2) from presenting knowns to revealing unknowns (e.g., is the map for displaying known information or for exploration?), and (3) from low to high interaction (e.g., a static map vs. an exploratory interactive mapping tool).

Figure 1.3.2 (Cartography)³

Credit: MacEachren and Taylor, 1994
 

These dimensions are often correlated, hence the shown corner-to-corner continuum from visualization to communication. A printed map in a magazine article, for example, we could classify as a tool for communication, while an exploratory mapping tool designed for epidemiologists would be better described as (geo)visualization.