A new study of the behavior of ravens suggests that their ability to infer that they are being spied on shows that they possess a part of of humans' ability to interpret the thoughts of others, Christian Monitor reports.  

The new findings were released Tuesday in a study in Nature Communications.

"What really is the feature that's unique and special about human cognition?" asked co-author Cameron Buckner, a philosopher at the University of Houston.

The researchers that that it is the human ability to see things through another person's eyes, and to think about what they might be thinking, skills that is referred to as "Theory of Mind." 

The authors suggest that ravens do have a basic Theory of Mind.

Earlier studies with chimps, monkeys and ravens have also suggested a basic Theory of Mind. However, researchers still don't know whether the animals really know what others are thinking or they just reacting to physical stimuli.

 "This was a really difficult problem to overcome," Dr. Buckner says in a phone interview with The Christian Science Monitor.

Thomas Bugnyar and colleagues at the University of Vienna, Austria, devised an experiment to rule out the possibility that birds are responding to another's cues, New Scientist reports.

For the study, the researchers separated two experiment areas with a wall, which they fitted with a window and a small peephole, visible when the window was shut. The researchers offered food to ravens in both rooms, with the windows first open, then closed and then observed the baseline caching behavior.

In another experiment, 10 birds were trained to look through the open peephole and spy on a human researcher burying some cheese. Later, the window was fully opened, and they could go find the cheese.

"Because all available behavior-reading cues have been controlled for in the test condition - there is no actual competitor whose gaze could be read, and the situation is novel from the subject's perspective - these data provide clear evidence that raven social cognition cannot be reduced to behavior-reading," the team wrote.

The ravens met the researchers' criteria for Theory of Mind by incorporating information from their own experiences with new ones, to predict how others might act and how to adapt their own behavior accordingly.