Humans who smell a pillow, shirt, shoe or other object that was in close contact with another person may be reminded of a certain someone. New research suggests squirrels have a similar ability to not only associate smells with particular squirrels, but to also create mental images of them.

The study, published in this month's Animal Behavior, represents the first time the ability has been demonstrated in rodents. A second, not-yet-published study by other researchers indicates hamsters also have the skill.

Like humans, squirrels must first be familiar with an individual before an odor can become associated with that other animal. A husband, for example, could smell his wife's perfume in an elevator and be reminded of her, but a perfume he has never smelled before could trigger no such memories.

"Squirrels need to be familiar with others to be able to put all of an individual's odors into a representation of that individual, as if repeated interactions make that individual meaningful, and thus worthy of remembering at this level," explained Jill Mateo, who conducted the research.