In his article, Roberts argues that time is a human construction, created to keep track of such things as days and significant events. Time-keeping devices from sundials and precise clocks to wristwatches revolutionized how humans perceive time, and animals don't have the advantage of these tools.
How a Dog's Memory Works
Research on how dogs perceive time is limited. But we can learn more about it when look at the extensive research done on other animals, such as rodents, birds and primates. In his studies on how animals perceive time, animal cognition researcher William Roberts made some remarkable conclusions regarding animal memories, anticipation and more. He says that animals are "stuck in time" [source: Roberts]. By this he means that, without the sophisticated abilities it takes to perceive time -- like truly forming memories -- animals only live in the present. Roberts thinks animals are "stuck in time" because they can't mentally "time travel" backward and forward. Humans can consciously and willfully think back to specific memories and anticipate events. Animals cannot.
To many, this seems like a fallacious theory. After all, can't we train animals? And doesn't this training depend on the animals' own memories?
Not necessarily -- at least not in the way we usually think of memories, according to Roberts. Animals might be trained to do things in the same way young children are trained to do things. According to studies on children, by the age of four, kids have learned lots of things -- crawling, walking -- but without the mental ability to remember where or how they learned them [source: O'Neil]. In other words, they don't have the power of episodic memory, or the ability to remember particular events in the past. A dog can know how to respond to the command "sit" without having a memory of the specific event in which it learned that command.
That's not all that's at work in the dog's brain to help it, for example, impeccably predict the arrival of its owner. Internal biological rhythms also play their part, according to Roberts. Researchers have discovered from experiments on pigeons that an "internal clock" allowed them to learn when and where food would be available [source: Saksida]. Similarly, dogs might use circadian oscillators -- daily fluctuations of hormones, body temperature and neural activity -- to know when food is likely to hit the bowl or when owners are likely to return from work. Instead of remembering how much time passes between meals or what time meals are given, dogs react to a biological state they reach at a particular time of day. And they react the same way at the same time every day to this stimulus.
If dogs can't store memories like humans can, can they plan for the future? On the next page, we'll learn what dogs comprehend about the future time.