Chickens have a reputation for being, well ... bird-brained. But a comprehensive review of the latest research about the psychology, behavior and emotions of these underestimated domestic avians has revealed that they might have a lot more going on upstairs than they're given credit for, reports Phys.org.

The review, conducted by Dr. Lori Marino, senior scientist for The Someone Project, a joint venture of Farm Sanctuary and the Kimmela Center for Animal Advocacy, shows that studying chicken psychology can be a surprisingly labyrinthine endeavor, at least compared to what conventional wisdom might otherwise suggest.

"[Chickens] are perceived as lacking most of the psychological characteristics we recognize in other intelligent animals and are typically thought of as possessing a low level of intelligence compared with other animals," Marino said. "The very idea of chicken psychology is strange to most people."

But Marino discovered that chickens have distinct personalities and can outmaneuver one another while engaging in relatively complex social situations. For instance, chicken communication is quite complex, involving a large repertoire of different visual displays and at least 24 distinct and identifiable vocalizations. Chickens can produce signals such as calls, displays and whistles to convey information, a type of correspondence known as referential communication that is believed to require some level of self-awareness.

Another indicator of self-awareness: chickens have been shown to possess self-control when it comes to holding out for a better food reward, and they seem capable of self-assessing their position in the pecking order.

Chickens aren't bad at math or empathy, either

Free-range chickens exploring a pasture Chickens have more emotional range than we give them credit for. (Photo: sevenke/Shutterstock)

Communication and social intelligence aren't the only aspects of their acumen. They can also do math. Research has shown that chickens have some sense of numbers immediately upon hatching, being able to distinguish between quantities. Five-day-old chicks presented with simple arithmetic problems in the form of addition and subtraction performed impressively.

In one study, chickens were capable of remembering the trajectory of a bouncing ball that is temporarily hidden for up to 180 seconds, a measure comparable to many primates at the same task. Another study showed that they perceive time intervals and can anticipate future events.

And chickens experience emotions too, such as fear, anticipation and anxiety. They even possess a simple form of empathy known as emotional contagion, the phenomenon of having another individual's emotions directly trigger similar emotions in you.

It's an impressive array of cognitive abilities that might not be apparent to the untrained observer of chicken behavior. Taken together, each of these areas of research reveal chickens deserving of far more respect than they're given.

The review, which is published in the journal Animal Cognition, could influence how we think about chicken welfare going forward.

"A shift in how we ask questions about chicken psychology and behavior will, undoubtedly, lead to even more accurate and richer data and a more authentic understanding of who they really are," Marino said.