Do Dogs Remember the Past? Exploring Canine Cognition and the Power of Bonds
It’s a question that crosses the mind of any dog owner upon returning home to a slobbery greeting: Do dogs remember the past they share with their humans, and to what extent? Scientists have delved into the intriguing realm of dog memory for many years, and thankfully, the answer appears to be a resounding yes.
Unveiling the depths of nonhuman animal cognition, including that of dogs, is a challenging endeavor. The inability to access their innermost thoughts poses a significant barrier. Furthermore, humans tend to overinterpret the gestures of their companions, a phenomenon aptly illustrated by the tale of Clever Hans. This horse, in the early 20th century, was renowned for its apparent mathematical prowess. However, psychologist Oskar Pfungst revealed that Hans wasn’t solving equations; instead, he was responding to subtle cues from his owner. To this day, animal behavior scientists remain vigilant in mitigating the Clever Hans effect and other biases within their research.
To understand dog memory, it’s vital to distinguish between different types of memory. Semantic memory enables us to recall factual knowledge about the world learned previously. Most animals, especially mammals, are thought to possess this form of memory. In dogs, semantic memory allows them to remember what to do when their owner says "Stay!" (assuming successful training, of course). However, the ability to recall and mentally replay personal life experiences—those shaping future behavior—is known as episodic memory.
Canine Cognition: Beyond Simple Learning
In the past, some scientists argued that nonhuman animals lacked episodic memory, suggesting it required a level of self-awareness unique to humans. However, recent research has begun to challenge this perspective. Gregory Berns, a neuroscientist at Emory University, who studies canine cognition, asserts that dogs and many other animals possess the brain anatomy necessary for a form of episodic memory. One key structure, the hippocampus, acts as a memory index, according to Berns.
"Your memories are scattered throughout your brain," Berns explained to Gizmodo. "The hippocampus works by replaying those scattered memories in the rest of your brain when you recall something. You can’t do it without the hippocampus. So, do other animals do that? My guess is yes, they probably do. Because every mammal we’ve observed has very similar brain structures; they all have a hippocampus."
Unsurprisingly, dog owners often hold strong convictions about their canine companions’ memory. A 2020 survey revealed that a vast majority of dog (and cat) owners reported their pets remembering past events, even singular occurrences from years prior. Scientists have also sought to experimentally verify the presence of episodic memory in dogs.
Remembering Beyond Training: A Complex Feat
A 2016 study conducted by researchers in Hungary demonstrated that dogs could witness their owner performing an action and subsequently mimic that action when prompted with a specific command ("Do it!"). While this might appear as basic training, the researchers further showed that the dogs could replicate their owner’s actions on command, even during different tasks. This suggests that dogs need to remember observing someone else’s movements, even when not explicitly trained, and then figure out how to perform those same movements with their bodies. Such a complex cognitive feat is indicative of episodic-like memory.
The same research team published another study in 2020. They trained dogs to repeat certain actions upon command. However, the owners unexpectedly asked their dogs to repeat other actions, including those performed spontaneously in daily life, which the dogs successfully managed.
"The combined evidence of representing own actions and using episodic-like memory to recall them suggests a far more complex representation of a key feature of the self than previously attributed to dogs," the researchers wrote.
The Nuances of Dog Memory
While these studies provide compelling evidence, they are often based on smaller sample sizes, focusing on specific facets of cognition related to episodic memory rather than definitively proving its presence in dogs. Additionally, dog memory differs significantly from human memory. Research indicates that dogs and other nonhuman animals generally possess shorter memory spans compared to humans.
Despite these nuances, the overall evidence points towards a closer link between nonhuman and human memory than previously thought. Berns notes that detailed studies on rat brains have revealed evidence of event replay, such as running through a maze in their heads while dreaming.
"I think it’s fairly safe to assume that if that’s going on in rats, it’s most certainly going on in dogs, too," said Berns, who is also the author of the upcoming book Cowpuppy, a scientific memoir chronicling his exploration of cow intelligence.
Unforgettable Bonds: The Case of Hachiko
Beyond scientific research, countless anecdotes serve as compelling evidence for sustained dog memory. Perhaps the most poignant example is the tale of Hachiko, a Japanese Akita dog born in 1923. Hachiko would faithfully meet his owner, Hidesaburo Ueno, at Shibuya Station in Tokyo every day after his commute. This daily routine tragically ended in 1925 when Ueno passed away from a cerebral hemorrhage. Despite his owner’s death, Hachiko continued to return to the Shibuya Station at the same time every day for the next nine years, until his own death in 1935. While Hachiko’s faithful waiting was in vain, his unwavering devotion made him a revered hero in Japan, honored annually to this day.
Although dog memory may not mirror that of human memory, the bonds we forge with our canine companions appear to be unforgettable for both parties. The evidence suggests that dogs are capable of remembering past experiences, and perhaps, their love for us is a constant reminder of the powerful bond that transcends the boundaries of time.
