Earlier you wrote
Of course it's difficult to explain this association, because we don't know enough about brain chemistry.
The ontological ingredients, and the ways of combining them, which physics gives you are quite limited. You can make shapes (like your triangle), you can count objects, you can consider their motions and other changes of state, you can average quantitative properties, you can consider causal dependence and counterfactual situations. There might be a few other things you can do. But if you are going to have a mind-brain identity theory, and not property dualism, then something built solely using methods like the ones I just listed has to be the experience. It can't just be "associated with" the experience - that would be dualism.
Color is usually mentioned at this point, because it is pretty obvious that no amount of piling up particles, averaging their properties, and engaging in causal and counterfactual analysis, is going to give you redness where there was none, in the simple way that putting three stones in a field really does give you a triangle. If someone proposes that the experience of a certain shade of red is some complicated but purely physical predicate, object, or condition, then from the perspective of orthodox physical ontology, they are proposing a form of strong emergence. (Weak emergence is like the triangle.) And strong emergence is property dualism - it introduces new ontological ingredients.
But although color is the standard counterargument - because of its vividness - any sensation, any thought, anything involving a self, anything like the "experience of an object", is just as much unlike anything that can be made from physics in a weakly emergent way. I challenge you to find a single aspect of your experience which you can unproblematically identify with (and not just associate with) some imagined neurochemical correlate. In every case, you will be taking some subjectively manifest reality, and then saying to yourself, "that is really just neurons doing something"; and in every case, physics alone gives you absolutely no reason to think that neurons doing that has any subjective side to it.
If you don't want to be a dualist, you are going to have to take that subjectively manifest reality, admit that it exists somewhere in exactly that form, and somehow rebuild physics around it. But that is really hard to do.
Three rocks in a field aren't a triangle until there's a brain with a concept of 'triangle' that identifies them as such. Photons of a particular wavelength aren't red until there's a brain with a concept of 'red' that identifies them as such. A creature isn't conscious until there's a brain with a concept of 'consciousness' that identifies it as such.
Third one's tricky because of the self-reference, but that doesn't make it an exception to the general rule. Concepts are predictive models, a model can't make predictions unless it's running on a computer, b...
...at least not if you accept a certain line of anthropic argument.
Thomas Nagel famously challenged the philosophical world to come to terms with qualia in his essay "What is it Like to Be a Bat?". Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. Even if we deduce all the physical principles behind echolocation, even if we could specify the movement of every atom in a bat's senses and nervous system that represents its knowledge of where an echolocated insect is, we still have no idea what it's like to feel a subjective echolocation quale.
Anthropic reasoning is the idea that you can reason conditioning on your own existence. For example, the Doomsday Argument says that you would be more likely to exist in the present day if the overall number of future humans was medium-sized instead of humongous, therefore since you exist in the present day, there must be only a medium-sized number of future humans, and the apocalypse must be nigh, for values of nigh equal to "within a few hundred years or so".
The Buddhists have a parable to motivate young seekers after enlightenment. They say - there are zillions upon zillions of insects, trillions upon trillions of lesser animals, and only a relative handful of human beings. For a reincarnating soul to be born as a human being, then, is a rare and precious gift, and an opportunity that should be seized with great enthusiasm, as it will be endless eons before it comes around again.
Whatever one thinks of reincarnation, the parable raises an interesting point. Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.
The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?". If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects.
And this could be that animals lack subjective experience. This would explain quite nicely why I'm not an animal: because you can't be an animal, any more than you can be a toaster. So Thomas Nagel can stop worrying about what it's like to be a bat, and the rest of us can eat veal and foie gras guilt-free.
But before we break out the dolphin sausages - this is a pretty weird conclusion. It suggests there's a qualitative and discontinuous difference between the nervous system of other beings and our own, not just in what capacities they have but in the way they cause experience. It should make dualists a little bit happier and materialists a little bit more confused (though it's far from knockout proof of either).
The most significant objection I can think of is that it is significant not that we are beings with experiences, but that we know we are beings with experiences and can self-identify as conscious - a distinction that applies only to humans and maybe to some species like apes and dolphins who are rare enough not to throw off the numbers. But why can't we use the reference class of conscious beings if we want to? One might as well consider it significant only that we are beings who make anthropic arguments, and imagine there will be no Doomsday but that anthropic reasoning will fall out of favor in a few decades.
But I still don't fully accept this argument, and I'd be pretty happy if someone could find a more substantial flaw in it.