Author(s):
Sara Irina Fabrikant* - University of Zurich
Simone Garlandini - University of Zurich
Abstract:
We report on an empirical study to systematically investigate the effectiveness and efficiency of a set of visual variables widely employed in cartographic design to depict geographic information in map displays (i.e., size, color value, color hue and orientation).
We employ a bottom-up approach to evaluate the effects of the mentioned visual variables to render thematically relevant information in a perceptually salient manner using the "change-blindness" paradigm. Rensink et al. (1997) have demonstrated that observers have great difficulty noticing even large changes between two successive scenes in an animation when blank images are shown in between scenes (e.g., simulating a flicker). This change-blindness effect even operates when viewers know that they will occur.
The research hypotheses guiding our investigation are: "A more efficient visual variable is detected faster in a flicker display than a less efficient one" and "A more effective visual variable yields more accurate responses in a flicker display than a less effective one." In an ongoing factorial experiment we ask novice participants to study thematic maps presented in a flicker display mode, showing statistical information about an unknown region. We monitor participants' eye movements while they solve three types of map use tasks, including change detection, identification and localization.
With this evaluation methodology and empirically validated results on the effectiveness and efficiency of visual variables for spatial inference making with maps we hope to support cartographers in their design decisions to generate salient displays for thematically relevant information.
