Have you ever wondered how your dog always knows when the kids are about to come home, or why your cat starts acting up if you’re late filling the food dish? We know that animals can tell time to an extent – even if they can’t check their watches like we do – but we don’t know exactly how they do it. In case you’re curious, here’s what we uncovered about the way that animals tell time.
How Time and Memory are Related
Whether you’re a dog, a bird or a human, telling time without a clock all comes down to memory. Specifically, there are two types of memory that we use to guide ourselves throughout the day: episodic memory and semantic memory.
This type of memory has been likened to mental time travel, and for many years, it was thought to be a uniquely human trait. An episodic memory is one in which you can remember the where, what, when and why of an action or a thing that you have learned.
For instance, let’s say that you learned a new cooking technique from a magazine that you were reading while you were standing in the checkout line at the grocery store last week. You know the “what,” which is the new technique. You can also remember why you learned the technique – because you were reading a magazine. Where and when? Last week, in the checkout line at the grocery store! To put it more simply, you can not only envision yourself learning something, but you can also envision the time and place that you learned it.
Semantic memory works quite a bit differently. With this type of memory, you know that something happens or needs to be done in a certain way or at a certain time, but if someone were to question you about where or when you learned this thing, you wouldn’t have a clear answer for them.
Think of it this way: Imagine that you’ve pulled up to a stoplight that just turned red. If it’s a stoplight that you encounter often, then you probably instinctively know approximately how long it will take before the stoplight turns green again. But, chances are, you can’t remember a specific day during which you learned how long you’d have to wait at this particular light.
Semantic and Episodic Memory in Animals
The challenge for scientists is in finding out how many mental gymnastics animals are doing to tell time. We know that most animals have semantic memory – that’s the type of memory that lets your pets know when its dinnertime or when you’re about to get home from work. But no one can say for certain if your puppy can actually think back to the first time he realized that your kids walked through the front door each day at 3 p.m.
However, research suggests that at least some animals can tell time using episodic memory. A 2006 study by the University of Edinburgh focused on hummingbirds and their ability to tell time with episodic memories. Researchers used eight artificial flowers filled with nectar, and the flowers were refilled on different schedules throughout the course of a day – some every 10 minutes and others every 20 minutes. The hummingbirds learned how often the flowers were being filled and which flowers were being filled at different times.
A different study, this one from researchers at the University of California, Davis, looked at Western scrub jays. In this experiment, the jays were given two different kinds of food – wax worms that went bad after a few hours and nonperishable peanuts. The jays learned to sort their food into two separate cashes, and they knew to visit the cache with wax worms before they spoiled. In other words, the jays knew the what, where, when and why, almost as if they had episodic memories just like humans.
When it comes to dogs, many trainers successfully teach dogs to sit and stay for three minutes or lay down and stay for five minutes. Some researchers would say that this is evidence for episodic or episodic-like memory, while others would say that this boils down to conditioning (semantic memory). When you and your pup are out for a walk and you decide to stop at a store, the reason that your dog keeps constant watch on the door may be because he doesn’t have an episodic memory that tells him how long you’ll be inside.
The trouble with learning how animals tell time is that we can’t simply ask them how they do it! What do you think? If your pet could talk, would he or she tell you about the first time the two of you went for your morning walk? Share your thoughts in the comments section!