Grey parrots use reasoning where monkeys and dogs can’t

Research suggesting that grey parrots can reason about cause and effect from audio cues alone- a skill that monkeys and dogs lack- is presented in Proceedings of the Royal Society B today.

Christian Schloegl and his team at the University of Vienna, let six parrots choose between two containers, one containing a nut. Both containers were shaken, one eliciting a rattling sound and the other nothing. The parrots preferred the container that rattled, even if only the empty container was shaken.

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.

So how do parrots compare to other animals? In this task, only three-year-old human children and the great apes were instantaneously successful and managed to use the absence of noise to infer that the reward is located in the alternative container. Dogs, monkeys and baboons are unable to make this inference.

Surprisingly, the performance of the birds was sensitive to the shaking movement: they were successful with containers shaken horizontally, but not with vertical shaking resembling parrot head-bobbing. Thus, grey parrots seem to possess ape-like reasoning skills, but their reliance on these abilities is influenced by low-level interferences.