Macaques continued to search for answers to an unsolvable laboratory task, seemingly refusing to believe that the correct answers were random and inconsistent.

In Chapter 1, “The Science of Animal Dreams,” author David M. Peña-Guzmán relays the history of researchers digging into the mental realities of nonhuman brains.

Research shows that humans aren’t the only animals whose imaginations run wild while they sleep.

And how do scientists go about answering that question?

In two related studies, researchers describe huge chromosomal rearrangements and about 500 novel gene clusters in the octopus, squid, and cuttlefish genomes, which they say could help explain how they evolved their extraordinary brains.

It was the first time a bird has removed a tracking device, and the second time a bird species showed cooperative “rescue” behavior.

The cephalopods resisted temptation for up to 130 seconds to earn their favorite food, hinting at sophisticated cognitive abilities such as planning for the future.

Directing an object on a screen to a target provided a tasty reward.

The familiar word elicits a twitch of the ears or swish of the tail, suggesting felines can distinguish their names from other words.

Nearly 50 years after its development, only a handful of creatures have passed the self-awareness exam. A new attempt with fish highlights a debate over the test’s use and meaning.

Goffin’s cockatoos customize tools to accommodate a specific need.

Louis Herman, who made seminal discoveries on dolphin cognition, has passed away at age 86.