This only works for fairly straightforward temporal relationships. Perceptual properties of dynamic visual variables Cartographers normally don't make maps for other cartographers, but for map-users. Just as much as for traditional static maps, this is true for cartographic animations. The goal of the animation can only be achieved if the visual variables used, be they static or dynamic, give the user the desired stimuli, thus helping him to understand the phenomena depicted. Therefore the kind of stimuli the visual variables give to viewers should be understood.
Association is therefore useful to indicate groups of different quality or character.
It should be clear that we need to know the perceptual properties of the dynamic visual variables as well. In recent literature this need has been stressed quite often, but not much work has been undertaken so far into actually finding out these perceptual properties. As part of an MSc-thesis at the Cartography department of Utrecht University, some limited preliminary studies into this problem were done by testing reactions of viewers on the use of dynamic visual variables in cartographic animations. The tests These test are only a first attempt to shed some light into the subject matter and should be considered an impulse for further research. Only ten persons were tested, all of them professional cartographers or cartography students.