Visual reasoning is the concept that your visual system has evolved to make sense of the world and in doing so has developed unique abilities. These skills allow us to see patterns, detect changes, and spot relevant visual information. For example, look at the image below. What do you see?
Did you see the panther in the grass? Don’t worry if not. Most people can’t see the predator because the relevant color information is missing. How about in the image below?
Now the panther is clearly visible because you can use your visual system to group colors of the vegetation together and the color of the feline stands out in contrast.
This example illustrates how we often depend on our eyes to reason about the world around us.
What’s more, we can use design to help viewers think. We can create designs that utilize our eyes to reason about information.
An iconic example of visual reasoning is from Edward Tufte’s description of an 1854 cholera epidemic in London. British Dr. John Snow published a paper in 1849 arguing that cholera, a fast acting deadly intestinal disease, was spread by sewage-contaminated water . Few doctors found merit in this theory and the belief prevailed that cholera was spread through inhalation. Using the novel approach of field observations, Dr. Snow began mapping a rapidly spreading cholera epidemic. He discovered that there was a popular water pump at the center of the outbreak (see map below).
Mothers used this pump to clean babies’ diapers, and Dr. Snow used his map as evidence to convince local officials to close the pump, which halted the outbreak (Tufte & Weise Moeller, 1997). This case story exemplifies how we can use our visual system to detect patterns in information that we couldn’t previously see.
To use visual reasoning, you must capitalize on what our visual system is good at and use that to allow viewers to make their own connections. Stay tuned for future blog posts about what our visual systems are best at doing.
- Tufte, E. R., & Weise Moeller, E. (1997). Visual explanations: images and quantities, evidence and narrative (Vol. 36). Cheshire, CT: Graphics Press.
- Snow, J. (1849). On the fatal cases of inhalation of chloroform. Edinburgh Med Surg J, 72, 75.