This investigation of the encoding features of graphs begins with a description of a cognitive framework which allows designers to factor into the process of designing displays how people interpret the information found and what display properties are responsible for this interpretation. The framework also provides a performance measure for use in assessing alternative designs and cognitive effort. Properties of displays--features, dimensions, and configurations--that can be mentally represented and serve as a basis for response are also discussed, as well as the strategy used to determine which display property is actually being represented and a processing justification for its use. An experiment is then described in detail which used a speeded classification task to test whether any of the display properties discussed were actually the encoding features and to assess the degree of interference in two univariate and two orthogonal conditions. It was found that, if the display format was not compatible with the information to be presented, classification errors increased, which in turn would increase the likelihood of miscommunication at higher levels of processing. A 38-item bibliography, 7 figures, and 4 tables are attached. (LMM)