William Playfair and the Psychology of Graphs

The appeal of statistical graphs depends heavily on their ability to exploit our natural perceptual and cognitive capacities, which evolved to meet very different challenges. Although little was known about the brain two centuries ago, the inventors of statistical graphs must have had some intuitive awareness of how the visual system functioned. William Playfair, inventor of the time series line graph, the bar chart, and the pie chart, was particularly astute in his choice of designs. His written justifications, and the constructions themselves, indicate that he had an instinctive understanding of our psychological capabilities and, moreover, that he understood how to exploit them. He anticipated many ideas that are the focus of work in experimental psychology to this day