Long-term memory is any information stored in the brain for more than a few minutes that can be recalled or referenced when it's needed later on. Animals use different kinds of long-term memory for different purposes. Dogs use some forms of long-term memory, but they don't recall specific events the way humans do.
Dogs live in the moment. They're not able to "travel through time" in their memories the same way humans do. Our memories of past events are called "episodic memories." You may sit down and think, "Hmm, what did I do yesterday after I got home from work?" But your dog can't think back and say, "Let's see, it's been two days since you took me to the dog park... I think I'm due for an outing!" Because dogs can't conceptualize a "past" (episodic memories) or a "future" (theoretical situations based on past events), they are completely focused on the present moment.
So, if dogs don't experience time, how is it that they seem to "know" when certain things will happen, like walks and feedings? What we perceive as the dog "remembering" is often your dogs' natural rhythms moving him into different states of being. For instance, you feed your dog at the same time every day. When dinnertime comes and he goes to his bowl but it hasn't been filled, he comes to nudge and whimper. This isn't because he "remembered" that it's dinnertime, but that his internal clock's timer went off, so he expected food.
Spatial memory is the ability to recall where things are located and how a location is arranged. For example, imagine you took your dog for a long walk and when you returned home, your spouse had rearranged all the furniture in the living room. If your dog walked into the living room and looked around inquisitively, then sniffed all the furniture, this indicates that she has a spatial memory of your living room and she noticed the changes your spouse made to this space. Your dog's ability to recognize that a room she knows has changed is evidence that she has long-term memory.
Your dog remembers his training, not because he can recall the specific instances when you told him to sit, lie down and stay, but because his brain develops connections that remain after the training. For example, if you're training your dog to shake, and you give him a treat every time he puts his paw in your hand, his brain makes the connection that giving his paw gets him food. Then, when you ask your dog for his paw later, these connected neurons fire, and he completes the task. Your dog obeys because his brain has wired itself to respond in the way that gets him what he wants (a treat), not because he recalled a conscious memory and made a decision to follow the command. This kind of memory is called "procedural memory," and humans have it, too. It's what we use when we do routine things we no longer have to think about, like tying our shoes or brushing our teeth.
- Psychological Bulletin: Are Animals Stuck in Time? Roberts, William A.
- Psychology Today: Dogs Don't Remember
- Journal of Comparative Psychology: Spatial Memory in Dogs (Canis familiaris) on a Radial Maze, Macpherson, Krista and Williams, Robert A.
- John Knows Dogs: How Dogs Learn
- Posit Science: Implicit Memory
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