For almost as long as we have been writing, we’ve been putting meaning into maps, charts, and graphs. Some 1,300 years ago, Chinese astronomers recorded the position of the stars and the shapes of the constellations. The Dunhuang star maps are the oldest preserved atlas of the sky:
More than 500 years ago, the residents of the Marshall Islands learned to navigate the surrounding waters by canoe in the daytime—without the aid of stars. These master rowers learned to recognize the feel of the currents reflecting off the nearby islands. They visualized their insights on maps made of sticks, rocks, and shells.
In the 1800s, Florence Nightingale used charts to explain to government officials how treatable diseases were killing more soldiers in the Crimean War than battle wounds. She knew that pictures would tell a more powerful story than numbers alone:
Why Visualized Data Is So Powerful
Since long before spreadsheets and graphing software, we have communicated data through pictures. But we’ve only begun, in the last half-century, to understand why visualizations are such effective tools for seeing and understanding data.
It starts with the part of your brain called the visual cortex. Located near the bony lump at the back of your skull, it processes input from your eyes. Thanks to the visual cortex, our sense of sight provides information much faster than the other senses. We actually begin to process what we see before we think about it.
This is sound from an evolutionary perspective. The early human who had to stop and think, “Hmm, is that a jaguar sprinting toward me?” probably didn’t survive to pass on their genes. There is a biological imperative for our sense of sight to override cognition—in this case, for us to pay sharp attention to movement in our peripheral vision.
Today, our sight is more likely to save us on a busy street than on the savannah. Moving cars and blinking lights activate the same peripheral attention, helping us navigate a complicated visual environment. We see other cues on the street, too. Bright orange traffic cones mark hazards. Signs call out places, directions, and warnings. Vertical stripes on the street indicate lanes while horizontal lines indicate stop lines.
We have designed a rich, visual system that drivers can comprehend quickly, thanks to perceptual psychology. Our visual cortex is attuned to color hues (like safety orange), position (signs placed above road), and line orientation (lanes versus stop lines). Research has identified other visual features.