Discovery News provided this synopsis: "All of the dogs received preliminary training to open a sliding door using their head or a paw. The dogs then watched their owners open the door by hand or by head. For the latter, the owner would get down on the floor and use his or her head to push up or down on the sliding door. The dogs were next divided into two groups. Dogs in the first group received a food reward whenever they copied what the owner did. Dogs in the second group received a food reward when they did the opposite. All of the dogs were inclined to copy what the owner did, even if it meant receiving no food reward."
Last year, I wrote about a similar story where researchers demonstrated that domesticated dogs were more likely to be mislead by humans than wolves in the classic Piaget "A not B" experiment because we have just evolved to trust humans so much.