Emily Reynolds in Wired:
Cementing their status as the most terrifying of all the birds, a new study has found that ravens are able to imagine being spied upon — a level of abstraction that was previously thought to be unique to humans.
The ability to think abstractly about other minds is singled out by many as a uniquely human trait. Now, a study from the Universities of Houston and Vienna have found that ravens are able to adapt their behaviour by attributing their perceptions to others.
The study, published in Nature Communications, found that if a nearby peephole was open, ravens guarded pockets of food against discovery in response to the sound of other birds — even if they didn't see another bird. This was not replicated when the peephole was closed, despite hearing the same auditory clues.
According to the study's authors, the discovery "shed[s] a new light on Theory of Mind" — the ability to attribute mental states to others. A number of studies have found that animals are able to understand what others see — but only when they can see the head or eyes, which provide gaze cues. This suggests that these animals are responding only to surface cues, and are not experiencing the same abstraction as humans.