Inference in wolves and dogs: The "cups task", revisited

Inferential reasoning —the process of arriving at a conclusion from a series of premises— has been studied in a multitude of animal species through the use of the "cups task" paradigm. In one of the versions of this set-up, two opaque cups —one baited, one empty— are shaken in front of the animal. As only the baited cup makes a noise when shaken, the animals can locate the reward by inferring that only a baited cup would make noise, that an empty cup would make no noise, or both. In a previous iteration of this paradigm in wolves (Canis lupus) and dogs (Canis familiaris), wolves seemed to outperform dogs. However, due to the lack of control conditions, it was not possible to assess each species' inference capabilities, nor how they related to each other. The current study adds several conditions in which the baited cup, the empty cup, or no cups are shaken, in order to tackle this issue. Our results seem to indicate that wolves and dogs made their choices not based on inference but on the saliency and order of the stimuli presented, something that seems in line with the previous study. We discuss the potential causes behind the animals' performance, as well as proposing alternative paradigms that may be more apt to measure inference abilities in wolves and dogs.