When you think of the numbers one and ten, which of them feels like it’s on the left, and which is on the right? If you’re like most people, you think of the number one as being on the left.
This so-called mental number line is a trait you share not only with most of your fellow English speakers, but also with the majority of people on earth. And now, for the first time, a team of researchers has found direct evidence of a mental number line in a non-human species: chickens.
