Impacts of multiple color nominal coding on usefulness of graph reading tasks

Multiple line graphs have been extensively used in business, finance and education. Previous color researches suggested that high contrast may be useful for nominal information coding in information design. However, empirical studies on its impacts on the graph-reader´s perception towards usefulness of the multiple line graph have been rarely examined. This study conducted an experiment to evaluate graphs using two different color combinations. The participants perceived the high luminance contrast Red-Green-Blue graph is more useful than the low luminance contrast Orange-Green-Cyan graph for complicated tasks using multiple lines. There was no difference of perceived usefulness across simple tasks including using a single line. Despite of the results, participants´ actual task completion time shows there is no difference in terms of graph reading complexity between the two different color contrast groups.