We know that animals can use scent, color, and sound to recognize individuals, and they may also be able to recognize other attributes as well. A recent study on sheep intelligence indicates that easily herded animals may be smarter than originally thought. The sheep were shown pictures of other sheep and were subsequently rewarded if they moved toward a selected picture—in other words, the sheep learned which face produced a reward. Ultimately, it was shown that sheep were able to pick a selected picture 80 percent of the time and could remember up to fifty images for two years.