Perception of spatial dispersion in point distributions

This paper analyzes the perception of spatial dispersion on point distributions. Spatial dispersion is one of the major concepts communicated by dot maps. To promote efficient communication of this concept, two experiments were conducted to investigate the relationship between the perception of spatial dispersion and such map characteristics as spatial arrangement of points, number of points, symbol size, and map scale. Regression models were built on the basis of the experimental results to describe the relationship quantitatively. The obtained models enable map authors to predict the degree of spatial dispersion perceived by map readers. From the models and the results of a computer-assisted simulation, the following conclusions were obtained: 1) map scale greatly affects the perception of spatial dispersion; 2) spatial arrangement of points and number of points are also influential; 3) the size of point symbols does not significantly affect the perception of spatial dispersion.