Neither person interacted with the dog's owner in the control -- third -- group.
After watching the box-opening scene, the dog was offered food by the two unfamiliar people in the room.
Dogs that saw their owner being rebuffed were far more likely to choose food from the neutral observer, and to ignore the offer from the person who had refused to help, Fujita said.
Dogs whose owners were helped and dogs whose owners did not interact with either person showed no marked preference for accepting snacks from the strangers.
"We discovered for the first time that dogs make social and emotional evaluations of people regardless of their direct interest," Fujita said.