This paper presents results from an empirical research study designed to investigate the affect of data format on user exploration patterns of spatial data visualized through GIS tables and maps. An experiment was designed in which geographic data were organized into point, line, and area tables and maps. These data were explored through a customized GIS interface and user exploration patterns were recorded. The results provide support for the application of the dominant framework theories (that explain mental map formation from direct exposure to a real-world geographic environment) to learning spatial data visualized in GIS.