A new study has provided evidence suggesting that just like humans, great apes such as orangutans, bonobos and chimpanzees have the ability to comprehend the mind of others.
Prior to this study, the only known being capable of understanding the mental states and perspectives of others is humans.
The new research, which was published in the journal Science on Friday, Oct. 7, suggests that great apes have understanding of false beliefs, which is considered a hallmark of theory of mind — the ability to attribute mental states such as desires, perspectives, beliefs and intents to oneself and others and having the understanding that others' mental states are different from one's own.
Christopher Krupenye, from Duke University, and colleagues recorded the eye movements of three species of great apes, chimpanzees, bonobos and orangutans, while the animals were watching slapstick videos of a man dressed in a King Kong suit trying to fool another man.
The man watched the actor in a King Kong suit either hide a rock-like object or hide himself in a hay bale. When the man leaves, King Kong would move the object or himself out of the bale.
When the man returns, he does not know that the object or King Kong has moved but the apes that watched the videos do. Eye-tracking data revealed that most of the apes correctly anticipated that the man would go to the incorrect location. The animals looked at where the man last saw King Kong or the object.
The apes' correct anticipation of the man's false belief that King Kong or the rock remains in the same place suggests that they understand the man's perspective.
"This is the first time that any nonhuman animals have passed a version of the false belief test," Krupenye said. "If future experiments confirm these findings, they could lead scientists to rethink how deeply apes understand each other."
Comparative psychologist and study researcher Fumihiro Kano of Kyoto University said that the apes' concept of others' false beliefs is considered a critical aspect of cognition.
The findings also suggest that this ability is not unique to humans. It may have existed in the primate family tree for at least 13 to 18 million years since the time of the last common ancestors of the great apes and humans.
"Our results suggest that great apes also operate, at least on an implicit level, with an understanding of false beliefs," the researchers wrote in their study.