Graphics, such as maps, have been used since ancient times to portray things that are inherently visual. More recently, graphics such as diagrams and graphs, have been used to portray things that are metaphorically spatio-visual. The assumption is that graphics facilitate comprehension, learning, memory, and inference. Assumptions aside, research on static graphics has shown that only carefully designed and appropriate graphics prove to be beneficial. Despite enthusiasm for animated graphics, the research reviewed here on their efficacy is not encouraging. In cases where animated graphics seemed superior to static ones, scrutiny of the actual stimuli revealed that the animated graphics conveyed more information, especially about the microsteps between larger steps. Lack of benefit from animations of events may be because animations are difficult to perceive and because events are often conceived of as sequences of discrete steps. Overall, this analysis suggests two principles, Apprehension and Expression, for successful animated graphics, though these principles do not guarantee that animated graphics will be superior to equivalent static ones.