This is Huey. He has not met you yet, but he loves you, and he wants you to love him too. Almost all dogs are human-oriented, but Huey takes it to the next level. He has been known to hyperventilate with happiness when a friend arrives- and that’s after he’s been at home all day with his work-from-home owner, so it’s not loneliness or separation anxiety, he is just that happy to see you.
Sometimes Huey’s desire for affection puts him at odds with himself. For example if you tell him to stay and walk away, he wants to do what you said, but he also wants to be near you. He will literally vibrate with the effort it takes to stay in place. But once you tell him good puppy, all the strain goes out of him. He rushes over for his well deserved affection, and then he’s done. He might even go play with a chew for a bit.
If you’d like a more human example, consider the orgasm. Most humans on the edge of orgasm will do anything to finish it. Immediately post orgasm, they will do absolutely nothing. Even people who have multiple orgasms will usually have a final one after which they really don’t care.
According to The Willpower Instinct, dopamine release corresponds to the vibrating-with-effort phase, not the good puppy phase. Dopamine doesn’t mark pleasure, because pleasure doesn’t need to be marked. Dopamine tells you pleasure is just around the corner, so keep trying. Note that this is slightly different than Peter Redgrave’s timestamp hypothesis I talked about before, but either would account for a lot of available data. For example, people with ADHD (who are energetic and yet somehow unable to get themselves to do the thing to get the results they want) are on average low in dopamine, and almost all ADHD treatments increase dopamine availability*. Dopamine levels rise copiously during sex until orgasm, at which point they plummet. Dopamine is also heavily involved in addiction.
This makes slightly more sense to me than the timestamp hypothesis, but is less interesting. Normally interesting is a bad sign for a hypothesis (almost anything is more interesting than chance, and chance explains a lot), but I’m not sure that applies in this case. The timestamp hypothesis is a lot more specific and thus testable, the priming hypothesis seems sort of vague in comparison. And of course both could be true- dopamine simultaneously says “reward coming soon” and “reward is because of this”. Those actually make sense to go together, as opposed to some things our body has combined.
I’m never going to be able to conclusively prove one or the other sitting at my computer, but let’s talk about how they differ. Timestamp hypothesis suggests people with low dopamine will be attracted to things that make it is easy to distinguish what caused a reward, like video games and obsessive facebooking. Based on my friends and reddit, those are heavily associated with both depression and ADHD. My literature search turns up some support for this**, but nothing with a design I consider rigorous.
Timestamp covers the H in ADHD better (a low baseline makes a small increase more distracting than it should be), but priming seems more apt for ADHD- inattentive type (ADHD minus H) and depression, where nothing is attractive enough to pull the person out of their focal activity.
So the answer is “some of both plus probably some other stuff”. But variations in which of these dominate might explain why a given person reacts to low dopamine the way they do.
*In addition to changing other neurotransmitters and hormones. The brain is complicated and no one understands it.
**Most interestingly the effect of bupropion in treating video game addiction.