Effects of Depth on Height and Speed in Information Displays

What is it about?

When people look at an object, we adjust it's size according to the depth at which we perceive it to be. In other words, the perception of an object's size is based on both its actual size and its perceived depth. The two experiments in this paper investigated whether perceived height of an object in the air above a surface and the perceived speed of an object were likewise influenced by the depth of the object. The result of the first experiment showed that the relation between physical height and perceived height changed as perceived depth increased. In addition, Experiment 2 showed that the relation between actual speed and perceived speed changed as a function of perceived depth.

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Why is it important?

Quantitative graphs use height to show the amount of a variable. Three-dimensional graphs are becoming more commonplace. So, readers of these 3-D graphs will automatically adjust the perceived height of data indicators in the graph, potentially making the graph inaccurate. Likewise, interactive graphs are making greater use of motion as a way to represent data. However, the results of these experiments show that, in a 3-D graph, readers will also adjust their perceptions of speed based on the perceived depth of an object, also leading to possible inaccuracy and confusion.