In earlier research Justin Couchman, assistant professor of psychology at Albright College, showed that rhesus monkeys, a species which usually fail an important test of self-awareness – the ability to recognize themselves in a mirror – were able to recognize their own actions in some situations. He accomplished this by having them move a computer cursor with a joystick and identify actions they had caused.

His new study, published this fall in Animal Cognition, shows that monkeys, like humans, clearly understood their own actions and were not merely visually tracking the movements onscreen. This suggests that, like humans, monkeys may have a feeling of “self” that helps them make some decisions.

In the experiment, humans and six rhesus macaques housed at the Language Research Center at Georgia State University used a joystick to move a cursor.

They saw their own self-caused actions on a computer screen, as well as the movements of several other objects. The other objects could partially match their movements, or move exactly opposite their actions, or move around randomly.

“Monkeys showed a lot of similarities to humans,” he says. “They had an easier time distinguishing between their own actions and opposing actions – which, in humans, most strongly conflicted with their reported intentions.”

This suggests that the monkeys took their own intentions into account when making decisions, and may make distinctions between different types of actions that are not their own. He notes that, “Some animals might lack a sense of self entirely. Some might make a distinction between self and other. Humans, and now rhesus monkeys, have demonstrated that they make distinctions between different types of ‘others’”.

This is interesting, Couchman says, because rhesus monkeys have clearly demonstrated metacognition – the ability to monitor their own thoughts and intentions – but not Theory of Mind, which is the ability to know the thoughts or intentions of another being.

“They might not know that other animals have intentions that could directly conflict with their own, but they still somehow specially attend to the kinds of actions that might come from those intentions,” he says.

For example, two animals fighting over a piece of food would do well if they could specially attend to opposing actions. They might not understand the motivation of the other animal, but rhesus monkeys in the wild probably benefit from being able to pay special attention to those kinds of actions and “tune out” other types that are not as important.

In humans this process is usually a conscious experience that includes intentions, perceptions, and motor movements. Rhesus monkeys show behaviors that indicate they use and have access to the same types of information, and thus they may be having a similar experience.

Understanding the emergence of self-agency helps us see how the self-reflective human mind evolved and helps us look at the evolutionary roots of things like social responsibility and group dynamics, says Couchman.

“Humans know when we personally caused something to happen and we feel a sense of responsibility, often in a very profound way. We hold ourselves responsible and, using similar mental processes, we hold others responsible. This is one of the pillars on which our society is based. Monkeys might be showing us the first glimpse of that behavior.”