3. That guilty look isn't an expression of guilt — it's fear.

All the logic lines up: Your dog was left alone, did something they weren't supposed to do (that they know better than to do), and when they're called on it, their face says it all. Perhaps you're already saying "No! Bad dog! Bad dog!" or some variation thereof.

Dr. Horowitz's 2009 study, "Disambiguating the 'guilty look': salient prompts to a familiar dog behavior," specifically focuses on the concept of how humans interpret dog emotions through the scope of human emotion. More simply: Humans tend to misattribute dog emotions based on human emotions. The "guilty" look is a prime example of this.

"I look at a dog showing the guilty look and it feels guilty to me. It does! We're kind of wired to see it this way, so it's nobody's fault," Dr. Horowitz said earlier this year.

"It seems unlikely that they have the same types of thinking about thinking that we do, because of their really different brains, but in most ways dogs brains are more similar to ours than dissimilar," she said.

That first bit is especially important — the concept of "thinking about thinking," known as "executive function" — because it means dogs aren't likely to reflect on their past actions and decide they've done something wrong.

"When you adopted your dog, and suddenly you're living with a dog, within a week we have opinions about the dog's personality, what they're like and what they're thinking. It's a way to try to predict what's gonna happen next with an organism that we don't really know," Horowitz said. "So we use the language of human explanation, and we just put it on the dog."