I read a book about Chaser shortly before I got my pup. And I followed much a what I read, naming everything he came in contact with, talking to him using familiar nouns and verbs, not wasting words. At almost 3, he's not Chaser smart, but he has developed an ear that can recognize the most subtle variations in words, and he can figure out novel combinations of nouns/verbs sometimes with a direct obect. For example right after he learned the word window, he could generalize it to any glass that you look out through, and then I could tell him to "take the [object name] to the window" and he would find the nearest window (or glass door) and bring the given object there.
He was way ahead of a human child in terms of linguistic cognition up until maybe the age of about 1 and a half, then he maxed out. Having a dog with the verbal understanding of a toddler comes in handy sometimes...but rarely, mostly I just wish he could learn to walk on leash.
If you want to encourage the smart look into clicker training, particularly free shaping[1]. The most well known books are by Karen Pryor. You can train pretty much anything, and get insanely complex including the things this collie was doing.
For a decent introduction (there's a lot of crap on Youtube) this channel gives pretty good info, introductions, and lots of short videos on how to train all sorts of things: https://www.youtube.com/channel/UC-qnqaajTk6bfs3UZuue6IQ
Be warned, once it starts to work both dog and owner can find it (very) addictive. :)
Most impressive thing? First time seeing my dog stop and think, puzzle it out, then try something different. This is not mindless training by repetition.
[1] Edit: Free shaping is leaving everything to the dog to work out with human just providing helpful carefully timed nudges when he edges closer to the right thing. Before long the dog will start experimenting and look to you for reactions a lot more. It's magic, fast, and you'll transform your view of how smart your mutt is.
A dog's life is pretty boring. There's a lot of laying around, a lot of waiting to eat and go for a walk. A smart dog needs things to do, and it's work for you to make that happen. Talking, TV, computers, work, the things we fill our time with a dog can't participate in. My dog is in perpetual state of disappointment and mopiness, just waiting for the next interesting, stimulating thing to happen. I could train him for hours on end and he'd never get bored, but laying on the floor watching me sit in front of a computer, he can barely contain his boredom.
We had a trainer once who said the hardest thing for a smart dog to do is to just ignore stimuli. You're putting together furniture, cleaning the closet, setting up a stereo, what's that? where does it go? what does it smell like? Is this a game? Can I help?
Genuinely curious - is there any reason why person would potentially prefer a less smart dog? I always thought that, the smarter they are, the better companions they can be, so your comment got me wondering.
The smarter they are, the more they observe and learn. This means they also learn bad or annoying things and it can be very difficult to then train them out of it. A good example is a border collie I know that accidentally broke a screen door, then suddenly learned that all screens can be opened at will and no window was safe.
Smart breeds also need to be kept busy and entertained or they get anxious and angry. They'll start destroying property or fighting with others. If you don't have the time and energy, it's much better to get a less intelligent and mellow dog instead.
The problem isn't high intelligence per se, it's that high intelligence in dogs also correlates with high energy (this makes sense, most intelligent dogs are sheep herders, like border collies, which were expected to be working most of the day!) and other personality traits that can be less than ideal.
High energy dogs get bored, frustrated, or destructive when not given enough exercise. And a high intelligence just means they're that much more creative in finding ways to amuse themselves (that probably won't amuse you...).
Additionally, part of what makes dogs such amazing companions is their empathy for humans not just intelligence. The current dog of my aunt and uncle is pretty dumb, compared to the previous one. But he loves people, cuddling, and he's super mellow.
He still needs to be walked 3-4 times a day, but not particularly long and he's perfectly happy just chilling and lying next to you all Saturday. That fits much better into less active lives than something high energy that needs to run 10-15 miles a day...
I fostered a very smart dog at one point and came away a bit spooked, honestly. If you were hanging out with someone it didn't trust and said that you were going to the restroom, it would immediately walk into there and wait for you, and it could tell the difference between time concepts like 'soon' and 'later'. We never had any real problems with it, but the sense that it listened, understood, and did not speak back was unsettling.
Dogs differ widely in mentality, behavior, and energy levels. A border collie - for example - requires lots and lots of time and activity. If you haven't got that to offer, both you and your dog are much better off if you pick less demanding breed.
I had a stupid dog (took him months to learn his own name) and now I have a smart dog, and I really miss the dumb one. It was so easy to keep him happy and satisfied and well-adjusted. He loved people and was just happy to lay around all day and then hang out with us when we got home from work. The smart dog requires constant entertainment and interaction to keep him from going insane.
Energy levels are difficult with a smart dog that is less than 3 years old. My border collie has calmed down in the last year, but the first few years she needed 3-5 hours of both mental and physical stimulation daily.
One of the things that was very useful for me was that I got my dog while travelling, and he spent the first couple years of his life in different countries. The whole time I was keenly aware of the difficulties of picking up language, and so I would talk to him like I wanted someone to talk to me in Italian/Spanish/German/Czech...slowly, in simple phrases, using words I know in the present tense.
Just pretend you got picked up by aliens who only communicate via flashing lights. After months you might be able to associate certain light combinations and color are associated with food, with being allowed to use the bathroom, with types of interaction, and if you were really smart you might be able to figure out verbs and simple sentence structure, but those lights need to be flashing slowly and distinctly, and if the aliens start using the same light to mean two different things then you're going to get screwed up.
For another species to grasp our language is an incredible thing, something no human has ever done, you have to keep things incredibly simple and teach them as if you were teaching language, not just saying what comes into your head.
My dog is frequently confused when he eaves drops on conversations and hears some one talk, for instance, about a long drive to the beach last year, and he waits at the door excited to go. And I have to think why is he waiting at the door, does have to pee? why is he so excited?
He was way ahead of a human child in terms of linguistic cognition up until maybe the age of about 1 and a half, then he maxed out. Having a dog with the verbal understanding of a toddler comes in handy sometimes...but rarely, mostly I just wish he could learn to walk on leash.