We've had carefully selected Golden Retrievers in our extended family for 30 years. For a point of reference this is a breed that's ranked #5 in intelligence compared to all breeds. Our family dog is amazingly human-like, even after carefully trying not to anthropomorphize him and our feelings about him.
He has a vocabulary of about 50 words. He understands short sentences, or at least enough words in them to understand what we mean. "Go upstairs and find your ball", "Hey I put food in your bowl", "Go see your mom" (since he's an adopted pet we're his adoptive parents, dogs are not things to own). He responds like a human. He can practically tell you a whole story with his facial expressions. He can roll his eyes sort of by looking at the ceiling and making a face when he thinks we're being ridiculous, and it's different than a similar face when he thinks we're being obtuse. He even has a favorite movie, Snow Dogs. He pays close attention to the dogs and has done the eyeroll to the ceiling thing when the humans start making out. He cracks us up daily.
We've all seen a dog lift an eyebrow and tilt their head to say "what the heck are you talking about?" Tip of the iceberg. When you have a really smart one for a decade it's like having a furry kid in the family. A very well behaved one, but there you go.
I sort of feel sorry for people who never get to be "dog people", call a dog "it" and think the rest of us are crazy and just anthropomorphizing our pet. Most of us "dog people" don't need these studies to tell us anything. But I'm still glad they're studying.