A retirement home resident cuddles a Paro. The FDA considers the faux harp seal a Class II medical device.

© KIM KYUNG-HOON/Reuters/Corbis

You won't find this plush seal on the shelves of your local toy store or among the Gund, Webkinz or Furbies scattered on the floor of a kid's room. Rather, you're most likely to find it this toy in residential care facilities, in nursing homes and in hospitals -- and its intended audience is the geriatric set.

Meet Paro, the harp seal pup that's actually a therapeutic robot used to comfort dementia patients and offer cognitive therapy for older adults. It may look like a stuffed animal, but it's not considered a toy. The U.S. Food and Drug Administration (FDA) considers Paro a Class II medical device, along with X-ray machines and powered wheelchairs. Class I, in comparison, includes items such as adhesive bandages and arm slings, whereas heart valves and metal hip joint replacements are considered Class III. But unlike an X-ray machine, this Class II device is plushy.

Paro is about the size of a newborn baby; it weighs just about 6 pounds (2.7 kilograms) and is about 22 inches (57 centimeters) long. It's covered in antimicrobial white fake fur, and it responds to human interaction with head movements, wiggling legs and trills similar to those of the baby harp seal it's designed to look like. But unlike a real animal such as a therapy dog, this therapy robot runs on batteries (and recharges through its own pacifier).

It's equipped with lightweight 32-bit RISC embedded processors and five types of embedded sensors that allow it to interact with humans. Light sensors give it light and dark awareness, and tactile sensors tell Paro when it's being touched. Audio sensors allow it to hear what you say, temperature sensors let it know if the room it's in is hot or cold, and posture sensors alert the robot to when it's being held. These sensors, in combination with artificial intelligence (AI) software, enable Paro to learn. It takes time and repetition, but this robot will learn its own name, and it will adapt its behavior based on its users' behaviors. For example, if you hug your robot seal -- which would be considered a positive, good behavior -- it will coo, and then encourage that behavior again. Conversely, if you throw or otherwise harm the robot pup, it will remember the interaction leading to that response and discourage the action.