Sometimes, even though we know better, we treat a non-human thing as if it were a human. We call cars "he" or "she". I often say, "Look how sad my plant is," because I don't have a green thumb despite my best efforts. These are examples of anthropomorphizing.
The actual definition is when we assign human and physical attributes, emotions, or intentions to non-human things. Most often we use human emotions to explain behaviors in our dogs. We see physiological signals that lead us to believe an animal is happy, sad, guilty, jealous, etc.
read somewhere that science's view on it (a bit harsh, I'll admit) is the point where human curiosity meets human laziness. We apply things we are familiar with (ex. emotions) to things (ex. animals) to help us understand our surroundings. This is different from using science to understand our surroundings because those assignations actually cloud our judgement from seeing the truth of the matter. But it's easier to assign than to look for the truth because science requires a lot of critical thinking and trial and error, hence our laziness.
Remember the Futurama episode where we discover Fry's dog was waiting outside the pizza place every day for years for Fry's return that never happened? It was based on a real event in Japan in the 1930s where a dog named Hachiko would follow his master to the train station and wait all day for his master's return. One day, his master had died while away and didn't return. However, Hachiko followed the routine day after day for years.
Immediately everyone said it was because Hachiko was waiting for his master's return, because he was such a loyal dog. Anthropomorphism. Science would look at the whole picture. Hachiko was now homeless, and responsible for his own survival. People at the train station made special trips to bring him food. Food is good for survival. People would pet him; another form of reward. Essentially, the train station was the best place to be for a homeless dog. The city even erected a statue for Hachiko, that's how much this story is beloved. Much more beautiful an easier to think of a loyal dog than a homeless one trying to survive, eh?
Dogs have dog emotions, not human emotions.
Studies and experiments over the last decade or so have helped the case for dog emotions. Dogs are neurologically similar to humans, and the way they experience happiness. Similarly, mice can be depressed by bullying from other mice, and anti-depressants actually work on them.
But it's important to remember that the emotions dogs feel are not the same as what we feel. The difference is in the intentions behind the emotions, and the differences in our brains. Humans have developed very complex thinking, that results in very complex emotions, and dogs just don't seem to have that. Studies are being done on complex emotions like jealousy and fairness, but findings are still inconclusive. We do know that dogs experience happiness, love, disgust, fear/anxiety, and sadness.
The good and bad to anthropomorphism.
Humans feel closer to things that are similar to us. We use anthropomorphism to form strong attachments to things that are not human. I get sad when my plants die. Morally, we CARE MORE about things that we assign emotions, intentions, and physical attributes to. For dogs, this is great! It means we start enacting laws about the ethical and fair treatment of them, it means we feed them the best food we can, and we take them to the vet when they are sick. They live happier lives.
But it also means that we start believing a dog is responsible for their own actions. Punishments for "naughty" things, or more extreme cases abuse, lead to terrible situations because we stopped understanding the dog as a dog and started believing the dog was thinking like us.
Another downside to anthropomorphizing animals: children get mixed signals about animals.
Meaning kids have more of a foundation for scientific understanding of the world around them than if they are subjected to books with humanized characters, like Berenstain Bears & Are You My Mommy? However, humanized characters teach empathy to children, too, like in The Giving Tree.
All sounds confusing, right? What do we do?!
As a society, culture, and species, we need to learn to respect the differences in our two species, dogs and humans, as well as we do the similarities and learn when it's appropriate to apply a bit of anthropomorphizing.