It's no circus trick: researchers have shown that horses can count, despite 100 years of belief to the contrary.

By dropping apples one by one into two buckets, researchers determined that horses almost always chose the bucket with more apples, if the numbers were low (less than four). The horses chose randomly between buckets of four and six apples.

These results are consistent with findings for human babies, and indicate a basic ability to count and a propensity to learn greater sequences, said Claudia Uller, MPhil, PhD, lecturer in the Faculty of Education at the University of Cambridge, England, and primary author of the study.

She explained the horses could not see through the buckets, so they had to keep track of how many apples were dropped into each bucket. The buckets were presented to the horses for choice only after all the apples had been dropped. Artificial apples were used to prevent any effect of odor. Each of the 56 study horses was tested only once so as to not be influenced by learning.

Horses still consistently chose two apples over one when the single apple was twice the size, indicating that they prefer greater numbers to greater volume, Uller said.

"Horses are smart," Uller said. "Not only do they have special social skills, but they also have good memory, and they can count."

Even so, ever since the case of Clever Hans, the general scientific opinion has been that horses cannot count. Clever Hans, a famous German stallion, made international headlines in the early 1900s by hoof-tapping responses to mathematical equations with amazing accuracy. Scientists finally showed that Hans was