Perception Shapes How Different Cultures Group Star Constellations

Source: iStock image by shaunl licensed to Art Markman

When you look up into the night sky, you see a variety of stars that differ in their brightness and closeness. If you have learned about the patterns of stars in the sky, you may also have learned to identify particular configurations or constellations like the Big Dipper or Orion’s Belt.

If you grow up in the United States or Europe, then you may learn the names of constellations that reflect figures from Greek mythology. But other cultures have also noticed configurations of stars and given names to them.

A paper in the March 2022 issue of Psychological Science by Charles Kemp, Duane Hamacher, Daniel Little, and Simon Cropper addresses two interesting psychological questions about these configurations of stars. First, do different cultures actually see some of the same patterns in the night sky? If they do, then does that reflect something about the way that human perception creates patterns?

Of course, the paper wouldn’t be that interesting if different cultures saw radically different patterns in the night sky. While there clearly is some variation from culture to culture, the researchers analyzed data from 27 different cultures and found that there is a remarkable amount of similarity.

In particular, when you focus on the brightest stars in the night sky, you find that cultures tend to create similar groupings. Those groupings are not identical, but there is a lot of overlap across groups that independently decided how to view the night sky.

Given this similarity across cultures, the researchers explored whether simple visual principles could explain the groupings that are typically formed. In the early 20th century, psychologists identified principles that lead you to see things as being part of the same object versus a different object. They called these the Gestalt principles, using the German word for shape.

For example, think about what happens when there is a sign with pairs of lights that flash in sequence. You may see this as lots of pairs that move around the edge of the sign. This perceptual experience reflects that we tend to group things that look similar, things that are near to each other, and things that move together.

The researchers took a map of the stars and built a simple algorithm to determine which stars people would be likely to group together just based on visual characteristics. They focused only on reasonably bright stars that would look similar in the night sky and then grouped stars that are also reasonably close together.

Just based on these principles, the computational model was able to group stars that appear in many of the most popular groupings across cultures. Looking at the groupings that different cultures created, the model would typically account for a number of them completely, a few of them partially, and there were often some that the model did not find.

This pattern suggests that many of the groupings of stars that cultures make are based on simple visual groupings. Then, there are a few that have some added stars the model doesn’t include, which could reflect other perceptual or cultural factors. For example, a particular star might be important for navigation, so it might be included in a grouping. Or a grouping based on visual properties might resemble some object that is culturally significant, so other stars might be added to fill out the pattern.

Of course, every culture also has its idiosyncrasies. As a result, each had at least a few configurations of stars that didn’t correspond to an obvious perceptual grouping. But the main takeaway is that large numbers of the configurations that were culturally relevant also did have a clear perceptual basis. I find this paper fascinating because it suggests how aspects of our culture that become deeply embedded can have their roots in the way our perceptual systems work.