What do you see when you look at these photos—animals or humanmade objects?

Live in the urban jungle long enough, and you might start to see things—in particular humanmade objects like cars and furniture. That’s what researchers found when they melded photos of artificial items with images of animals and asked 20 volunteers what they saw. The people, all of whom lived in cities, overwhelmingly noticed the manufactured objects whereas the animals faded into the background.

To find out whether built environments can alter peoples’ perception, the researchers gathered hundreds of photos of animals and artificial objects such as bicycles, laptops, or benches. Then, they superimposed them to create hybrid images—like a horse combined with a table (above, top left) or a rhinoceros combined with a car (above, bottom right). As volunteers watched the hybrids flash by on a screen, they categorized each as a small animal, a big animal, a small humanmade object, or a big humanmade object.

Overall, volunteers showed a clear bias toward the humanmade objects, especially when they were big, the researchers report today in the Proceedings of the Royal Society B . The bias itself was a measure of how much the researchers had to visually “amp up” an image before participants saw it instead of its partner image.

That bias suggests people’s perceptions are fundamentally altered by their environments, the researchers say. Humans often rely on past experiences to process new information—the classic example is mistaking a snake for a garden hose. But in this case, living in industrialized nations—where you are exposed to fewer “natural” objects—could change the way you view the world.