Horses didn’t perform better than they did with the controls in finding the human behind the different screen heights, Amici said. Essentially, the horses seemed to choose a screen at random. | Photo: Courtesy Dr. Federica Amici

Swiss and German researchers say their latest study results indicate that horses don’t seem to be able to reason about size the way we do. In other words, it might not occur to horses that their 1,200-pound frames can’t quite hide behind a 5-inch-wide tree trunk.

“Our tests really show that horses fail to intuitively reason about object properties like solidity and weight,” said Federica Amici, PhD, of the University of Berne, in Switzerland. “But this doesn’t mean they aren’t intelligent. This simply means that horses may not especially require this ability.”

In their study, Amici and her fellow researchers tested 16 horses’ abilities to find a human hiding with a bucket of feed behind one of two black screens. In one test, the screens were of two sizes: one tall enough for a human to stand behind, the other not. In the second test, they tilted two equally sized screens toward the ground at different angles. A person could easily hide behind the bigger angle (80°) but not the smaller one (10°). The researchers had previously warmed the horses up to the idea that people can hide behind screens. They compared their results to control testing (two identically sized screens for the first test, two identically angled screens in the second)