Grey Parrots Use Reasoning Where Monkeys and Dogs Can’t
When the parrots were played a recorded noise, but the container was not shaken, they did not choose it. This suggests that grey parrots understand the causal link between nut, shaking and noise, which is otherwise only mastered by great apes, but not by monkeys or dogs.
More importantly, they also use the absence of noise during the shaking of the empty container to infer that this container does not contain a nut. This correct conclusion, from only one container being shaken, suggests that the parrots are making a two-step deduction. First, the presence and absence of noise has to be connected to the presence or absence of the reward, respectively. This information must then be used to deduce that the absence of noise in one container is predicting the presence of the reward in the other container.