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Very quickly – what did you have for lunch yesterday? Have you been with anyone? Where were you? Can you imagine the scene? The ability to remember things that happened to you in the past, especially going back and recalling small random details, is a hallmark of what psychologists call episodic memory — and new research shows that it’s an ability , which humans can share with birds called Eurasian jays.

With episodic memory, “you remember an event or an episode, hence the name,” said James Davis, first author of the study, which appeared May 15 in the journal PLOS One. “You experience it in your mind. It also includes other kinds of details that make up that experience, such as sounds, sights, even your thoughts or mood at the time.

Episodic memory differs from semantic memory, which is the recall of factual information, added Davies, a doctoral student in psychology at the University of Cambridge’s Comparative Cognition Laboratory.

“It’s often helpful to think of episodic memory as remembering, while semantic memory is just knowing,” he said. “It’s not really about conscious recall.”

Although episodic memory is an integral part of how most people experience the world, it can be difficult for scientists to prove whether nonhuman animals share this ability—after all, they can’t tell us what they’re thinking. For several decades, however, scientists have been developing experiments to examine the ability of animals to remember previous events and have found evidence of episodic-like memory in creatures as diverse as pigeons, dogs and cuttlefish.

Corvids – the group of birds that includes crows, ravens and jays – are known for being smart, and previous studies have shown that they are capable of episodic-like memory that can help them find bits of food they’ve hidden for later. In 1998, Dr. Nicola Clayton devised an experiment with jays in which the birds seemed to remember what types of food they had hidden in different places and how long ago.

This means of finding evidence of episodic-like recall—called the “what, when, where” protocol—has become a standard among animal memory scientists. But Davis, who is Clayton’s adviser, wanted to find other ways to test this cognitive ability.

“If you’re only using one methodology, then there’s potentially some error in that method,” Davis said. “If you use multiple different methodologies that test the same thing in quite different ways, then that leads to much more compelling evidence.”

Researchers developed a new approach involving Eurasian jays, and what they found may have implications for the study of human memory.

Davis and Clayton’s new experimental design is based on the concept of random memory.

“The idea is that with human episodic memory, we remember details about events that weren’t necessarily connected to anything at the time. We weren’t actively trying to remember that,” Davis said. “But then, if you’re asked about it a few days later, you might remember those details.”

This is a seemingly unimportant piece of information that you have not consciously committed to memory – for example, remembering what you had for lunch yesterday. This aspect of episodic memory is sometimes called “mental time travel.”

To find out if Eurasian jays are capable of mental time travel, the researchers worked with birds that had been trained to find food hidden under cups. Davis set up a row of four identical red plastic cups and let the birds watch him place a piece of food under one of the cups. The jays then had to remember under which cup the food was hidden. Easy enough.

For the next step of the experiment, Davis made small changes to the appearance of the cups, such as adding stickers or colored strings, but again hid the food under the same cup in the composition. To a bird looking for a treat, these strings and stickers seemed like unimportant random information – at that point they only had to worry about the position of the cup to find the food.

But in the final stage of the experiment, these small details of the decoration of the cup became unexpectedly important. Davis changed the position of the cups so that the birds could no longer rely on the once important information of which cup in the row contained food. (The treats were later removed from the cups to rule out the possibility that the birds were simply finding the food by smell.) However, after a 10-minute break, the jays were still able to find the treat cups.

Davis hypothesized that the birds’ mental process may have involved asking themselves, “Where’s the food? I remember going to the one with the black square on it. I’m going to go to that one,” Davis said. The jays appeared to go back in their memory to retrieve details about the decoration of the cups, and they were very successful in using this information to find the hidden food.

“This study provides strong evidence for episodic memory in Eurasian jays,” said Dr. Jonathan Crystal, professor of psychology and brain sciences at Indiana University Bloomington, who was not involved in the project. “If you can answer this unexpected question after incidental encoding, it becomes a strong argument that you can remember back in time to the earlier episode, which is the basis of episodic memory documentation.”

Crystal said studies like this one, which aim to identify animals’ abilities to form episodic memories, are important in part because of their potential role in the field of human memory research.

“The big memory disease is Alzheimer’s disease, and of course the most debilitating aspect of Alzheimer’s disease is profound episodic memory loss,” Crystal said.

Because Alzheimer’s drugs for humans are invariably tested on animals before reaching human trials, he noted, it’s important for scientists to be able to understand whether these drugs actually affect the memories that Alzheimer’s patients lose.

“It’s not enough to just improve memory, we need to improve episodic memory,” he said, and a better understanding of how to test for episodic-like memory in animals could help make that possible.

Kate Golembiewski is a Chicago-based freelance science writer interested in zoology, thermodynamics, and death.