"We have developed algorithms that allow a robot to determine whether it should deceive a human or other intelligent machine and we have designed techniques that help the robot select the best deceptive strategy to reduce its chance of being discovered," said Ronald Arkin, a professor in the Georgia Tech School of Interactive Computing, in a release about the study.

The researchers taught a robot how to recognize when a situation warrants the use of deception, then programed it to behave appropriately.

The researchers said the study - which was published this week online in the International Journal of Social Robotics - will help in places like a battlefield, where a robot can deceive an enemy soldier by creating a false trail, then hide so it will not be caught.

The researchers also said in a search-and-rescue operation, a robot may need to deceive in order to calm or get co-operation from a panicking victim.

"Most social robots will probably rarely use deception, but it's still an important tool in the robot's interactive arsenal, because robots that recognize the need for deception have advantages in terms of outcome compared to robots that do not recognize the need for deception," Wagner said.

An RFID tag can be small enough to be fitted to an ant's back and often use little to no energy, activating only when they are close to a reader. They have been used for years to keep track of livestock, authenticate ID badges, manage inventories or pay bridge and highway tolls.

"I've been involved with RFID for 16 years, and this is the very first year that things are exploding," he said.

Privacy organizations have long criticized the use of RFID chips in documents and items that could be used to track people's movements, determine their identities or make inferences about their habits.

Shortly after the Wal-Mart announcement, privacy organizations said the tags remained active after shoppers took them home and disposed of them, and could be used by marketers or criminals to find out what a person recently bought - including purchases buyers prefer to keep private.

But privacy advocates worry about how retailers themselves might use the information and about the possibility of cross-referencing data from costumers' loyalty cards and RFID-equipped purchases that could effectively identify and track how often shoppers go into the store and where they spend their time. Once information is collected, it's not always clear how it will end up being used or abused," she said.