READING BAR GRAPHS - EFFECTS OF EXTRANEOUS DEPTH CUES AND GRAPHICAL CONTEXT

Manipulating the way a graph is drawn influences viewers' ability to e xtract information from it. In a series of experiments with simple bar graphs, the authors varied the rendering characteristics and relative heights of the bars and asked participants to estimate the quantities portrayed. The addition of 3-dimensional (3D) perspective depth cues lowered accuracy. This accuracy disadvantage diminished when a short d elay was introduced before judgments were reported. The height of the judged bar relative to nearby graphical elements also affected accurac y; this effect was about 1 order of magnitude larger and remained inta ct when the delay was introduced. Nearby elements also affected viewer s' bias (under-or overestimation). These effects do not seem to be due to misestimation of object depth. The results suggest that warnings a bout accuracy decrements due to 3D shading may be overstated, whereas distortions due to neighboring elements should be of more concern.