The Discrimination of Graphical Elements
DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)
Pagination or Media Count:
A model is proposed to account for how people discriminate quantities shown in pie charts and divided bar graphs i.e. which proportion is larger, A or B The incremental estimation model assumes than an observer sequentially samples from the available perceptual features in a graph. The relative effectiveness of sampled perceptual features is represented by the spread of probability distributions, in the manner of signal detection theory. The models predictions were tested in two experiments. Participants took longer with pies than divided bars and longer with non-aligned than aligned proportions in Experiment 1. In Experiment 2, participants took longer with divided bars than pies when graphs were of unequal size. Generally, graphical formats producing longer response times incurred a greater time penalty when the difference between proportions was reduced. These results were in accordance with the models predictions. Implications for graphical display design are discussed.
- Printing and Graphic Arts