Some birds can use ‘mental time travel’, study finds | CNN

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Real quick, what did you eat for lunch yesterday? Were you with anyone? Where have you been? Can you imagine the scene? The ability to remember things that happened to you in the past, particularly going back and remembering small, incidental details, is a hallmark of what psychologists call episodic memory – and new research indicates that it t’s an ability that humans may share with birds called Eurasian jays.

With episodic memory, “you remember an event or an episode, hence the name,” said James Davies, first author of the study published May 15 in the journal PLOS One. “You kind of relive it mentally. It also involves other types of details that make up that experience, like sounds, sights, even your thoughts or mood at the moment.

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

“It’s often helpful to think of episodic memory as remembering, whereas semantic memory is just about knowing,” he said. “There’s no real conscious recall.”

Although episodic memory is an integral part of how most people perceive 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 think. However, for several decades, scientists have designed experiments to study the ability of animals to remember past events, and they have found evidence of episodic-like memory in creatures as varied as pigeons, dogs and cuttlefish.

Corvids – the group of birds that includes crows, crows and jays – are known to be intelligent, and previous studies have suggested that they are capable of episodic memory, which may help them find pieces of food they hid for later. In 1998, Dr. Nicola Clayton designed an experiment with scrub jays in which the birds seemed to remember what types of food they had hidden in different locations and for how long.

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

“If you only use one methodology, that method may contain errors,” Davies said. “If you use several different methodologies that test the same thing in very different ways, it leads to much more conclusive evidence.”

The researchers designed a new approach involving Eurasian jays, and their findings could have implications for the study of human memory.

Davies and Clayton’s new experimental design draws on the concept of incidental memory.

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

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

To find out whether Eurasian jays are capable of mental time travel, researchers worked with birds trained to find food hidden under cups. Davies arranged a row of four identical red plastic cups and allowed the birds to observe him putting a piece of food under one of the cups. The jays then had to remember in which cup the food had been hidden. Easy enough.

For the next stage of the experiment, Davies made few 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 lineup. For a bird searching for a treat, these strings and stickers were apparently unimportant incidental information: at this point, it only needed to worry about the position of the cup to find the food.

But in the final phase of the experiment, these small details of decorating the cups became unexpectedly important. Davies changed the position of the cups so that the birds could no longer rely on the once-crucial information about which cup in the row contained food. (The treats had since been removed from the cups, to rule out the possibility that the birds found the food by scent alone.) However, after a 10-minute break, the jays were still able to find the cups containing the treats.

Davies suggested that the birds’ mental process might have involved asking themselves: “‘Where is the food?’ I remember going to the one with the black square on it. I’m going to go,” Davies said. The jays seemed to go back into their memories to retrieve details about the cup decorations, 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. Jonathon Crystal, senior professor of psychological and brain sciences at Indiana University Bloomington, who was not involved in the project. “If you can answer this unexpected question after accidental encoding, it becomes a strong argument that you can remember back in time to the previous episode, which is central to the documentation of episodic memory.”

Crystal said studies like this, 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 a profound loss of episodic memory,” Crystal said.

Since Alzheimer’s drugs intended for humans are invariably tested on animals before being tested on humans, he noted that it is important for scientists to be able to determine whether these drugs actually affect the type of memories that Alzheimer’s patients lose.

“It’s not enough to improve memory, we need to improve episodic memory,” he said, and a better understanding of how to test 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.