Circle Size Judgment and Map Design

Recent research in size judgment of circles has demonstrated that the exponent n in Stevens' power law is not stable and is influenced by various factors. A literature survey suggests that these factors include the testing method, test instructions, the standard, the stimulus range, and the sequential effect. Such influences have certain implications for map design including that the reader's attention should be drawn to the fact that it is the areal property of circles that represents value and that the choice of standard circles for the legend is a critical matter in attempting to influence estimation.