The Effect of Global-Scale Map-Projection Knowledge on Perceived Land Area

The acquisition and conceptualization of spatial knowledge are important topics in human spatial cognition. At the global scale, maps are our primary graphic source of information; however, they distort the size and shape of geographic features. If a distorted reference is used and the reader assumes it to be accurate, it may inappropriately influence decision making and, possibly, the shape of our global-scale cognitive maps. This paper examines trends in perception of land area, using equal-area and non-equal-area references, as well as investigating how map-projection knowledge can influence interpretation of land area. Results from the land-area studies show that map readers attempted compensation for projection distortion only when using the Mercator projection as a reference, and only for certain regions displayed on the Mercator projection. For other reference materials there is no attempted compensation for perceived distortion, even when participants believe that the reference is distorting land area. It is also apparent that most participants have limited projection knowledge and have difficulty transferring this knowledge to other projections or to practical application tasks. Both of these findings have implications for understanding perceptual issues in map reading and for determining where distortions can be introduced at the encoding stage of cognitive map development.