Landmark-based search memory in the domestic dog (Canis familiaris)

Recent studies have suggested that any animal that relies on landmark-based search memory encodes and uses metric properties of space to navigate. So far, however, metric information provided by landmarks has been predominantly investigated in avian species. In the present study, I investigated whether the domestic dog (Canis familiaris), a mammalian species, encodes the distance and direction from landmarks. Dogs were trained to find a ball hidden next to an array of two distinct landmarks that remained at a constant location in a room from trial to trial. After training, the dogs were occasionally tested on unrewarded conditions where the array was either left in its usual position or shifted laterally, perpendicularly, or diagonally relative to the rear wall of the room. Although the dogs significantly shifted their search as a function of the displacement of the landmarks, they did not search at the predicted coordinates of the goal relative to the shift of the landmarks, suggesting that the global cues available in the testing room were also encoded and used by dogs to locate the position of the goal.