Fig. 10. The first 15 maps that were presented during each Turing Test were randomly selected from among 17 real maps that were clipped from within this five-state source map. The source map represents areas that are similar with regard to mean annual temperature, mean annual precipitation, elevation, soil nitrogen, soil organic matter, and the amount of soil water content available to plants. Black outlines indicate the borders of each clipped map. The development of the source map is described at http://www.esri.com/library/userconf/proc97/proc97/to250/pap226/p226.htm.