Study shows: Some birds can undertake “mental time travel” | CNN

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Real quick – what did you have for lunch yesterday? Have you been with someone? Where have you been? Can you imagine the scene? The ability to remember things that happened to you in the past, especially remembering small, random details, is a hallmark of what psychologists call episodic memory – and new research suggests that people may have this ability Share birds called jays.

In episodic memory, “you remember an event or episode, hence the name,” said James Davies, lead author of the study, which appeared May 15 in the journal PLOS One. “You mentally relive it. It also includes other types of details that make up the experience, so sounds, sights, even your thoughts or your mood at the time.”

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

“It’s often helpful to think of episodic memory as memory, while semantic memory is just knowledge,” he said. “There’s no real conscious remembering involved.”

While episodic memory is an essential part of how most people perceive the world, it’s difficult for scientists to prove whether non-human animals have this ability – after all, they can’t tell us what they’re thinking. However, for several decades, scientists have been developing experiments to study animals’ ability to remember past events, and have found evidence of episodic memory in creatures as diverse as pigeons, dogs and squid.

Corvids – the group of birds that includes crows, ravens and jays – are famously clever, and previous studies have shown that they have episodic memory that may help them find pieces of food they’ve hidden for later. In 1998, Dr. Nicola Clayton designed an experiment with Florida jays in which the birds appeared to remember what types of food they’d hidden in different places and how long ago they’d hidden it.

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

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

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

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

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

It’s a seemingly unimportant piece of information that you haven’t consciously memorized – for example, remembering what you had for lunch yesterday. This aspect of episodic memory is sometimes referred to as “mental time travel.”

To find out if jays are capable of mental time travel, researchers worked with birds that were trained to find food hidden under cups. Davies set up a row of four identical red plastic cups and allowed the birds to watch as he placed a piece of food under one of the cups. The jays then had to remember which cup the food was hidden under. Easy enough.

For the next step of the experiment, Davies made minor changes to the appearance of the cups, such as adding stickers or colorful strings, but again hid the food under the same cup in the array. For a bird searching for a treat, these strings and stickers were seemingly unimportant peripheral 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 the cup decoration became unexpectedly important. Davies changed the position of the cups so that the birds could no longer rely on the once-important 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 were finding the food by smell alone.) After a ten-minute break, however, the jays still managed to find the cups containing the treats.

Davies suspects that the birds may have been thinking, “Where’s the food? I remember going to the one with the black square. I’m going to that one,” says Davies. The jays seemed to be searching their memories for details about the cup decorations, and they were very successful at using that information to find the hidden food.

“This study provides strong evidence for episodic memory in jays,” said Dr. Jonathon Crystal, provost professor of psychology and brain sciences at the University of Indiana Bloomington, who was not involved in the project. “If one can answer this unexpected question about random encoding, it is a strong argument for the ability to recall the earlier episode, which is the core of the documentation of episodic memory.”

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

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

Since Alzheimer’s drugs for humans are always tested on animals before being tested on humans, it is important for scientists to be able to examine more closely whether these drugs actually have an impact on the types of memories that Alzheimer’s patients lose.

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

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