Functional Efficiency, Effectiveness, and Expressivity of Bertin’s Visual Variable Colour Hue in Thematic Map Design

Abstract

Notions of functionality of thematic maps that were built around Robinson’s seminal work ‘The Look of Maps’ were later redefined to include questions of efficiency and effectiveness. The possibility of the use of digital technology in map creation and reproduction widened the scope of map design research from evaluation of whole maps to the evaluation of basic graphic elements – the graphic or visual variables. The paper attempts to asses and validate one of the variables of Bertin’s model of visual or graphic variablesthe visual variable colour hue on the basis of available experimental evidence related to the functional efficiency, effectiveness and expressiveness of the variable at different perceptual/cognitive levels and the experimental evidence from design research in thematic cartography. The analysis of results both from psychology and design research in thematic cartography show that the two levels association and selection have adequate empirical support in the above two areas. However, the experimental results for the level order are contrary to formulations of Bertin. In case of both hues ordered in spectral progression and hues ordered around a unique hue variability expanse or range which extend to either of its limits in a limited ambit of ordered steps adequately perform at the level of order.