A happy lab rat? Check the ears!

What do you think of when you hear the term "lab rat"? Chances are, you might not picture an animal happily playing rough-and-tumble with a human handler and then coming back for more. Scientists have traditionally studied negative expressions in rats, as they are more reliable and easier to elicit (imagine a rat freezing still when exposed to sudden loud noise). However, a group of researchers from the Division of Animal Welfare at the University of Bern in Switzerland decided to see if they co