from the fuzzy-thinking dept.
There has long been a clear hierarchy of intelligence in the psychology lab with monkeys are at the top, then rats, and finally mice at the bottom, "cute and fluffy but not all that bright." For at least a hundred years researchers have used rats in their psychology experiments, assuming that they were the smarter of the two lab rodents but now Rose Eveleth reports at The Atlantic that new research shows that that might not be true and that mice can perform decision-making tasks in the lab just as well as rats can. "Anything we could train a rat to do we could train a mouse to do as well," says Tony Zador. This finding is important because using mice in experiments instead of rats could open up all kinds of new research options. For one thing, scientists have been able to manipulate a mouse’s genome in really useful ways, silencing certain genes to figure out what role they play. There are mouse models for everything from Alzheimer’s to Parkinson’s. Being able to put those mice through the paces of a psychology experiment could help researchers connect diseases with the behaviors they impact.
So where did this idea that rats are smarter than mice come from, anyway? Zador says it’s a historical bias. “There was 100 years of practice in training rats. And basically when people tried to treat the mice in exactly the way they treated the rats, the rats seemed smarter," says Zador. In other words, "over the course of 100 years people had figured out how to train rats, and that mice aren’t rats.” You might think that mice and rats would be basically the same when it comes to these kinds of things, but Zador points out that mice and rats diverged somewhere between 12 and 24 million years ago. For comparison, humans and chimpanzees split somewhere between 5 and 7 million years ago. So it's no surprise that mice behave differently than rats, and that that difference impacts their training in the lab. "The mouse is uniquely placed at the interface between experimental access and behavioral complexity, making it an ideal model for the study of adaptive decision-making. Successful behavioral paradigms, however, rely on targeting designs to the idiosyncrasies of the mouse from the outset, rather than simply assuming that mice are little rats."