The goal of science is to test and quantify whatever it is that the scientist is studying....
You seem to have mounted an argument from incredulity to dismiss the entire scientific field of
neuropsychology, not to mention psychology itself. One can certainly design and execute experiments in which behavior can be measured on the basis of mental activity, including memories. There is a vast literature on the subject, but it is possible that you have never actually studied it formally. You don't need to be able to put memories on a movie screen, because they aren't really equivalent to moving pictures. You can represent brain activity on a movie screen and correlate it with controlled mental activity. That is exactly what a great many scientific studies have done already. Just as one example, consider the famous
Libet experiments, which are often debated in discussions on the nature of free will. I could give you many others, but that one is a good example of how one goes about designing and conducting an experiment.
Look I would like to get back to the original question you raised in the OP and try to explain where (and why) I come down on this:
“they are what philosophers call "substance dualists" (aka Cartesian dualists) in that they believe in an immaterial spiritual plane of existence that is independent of physics. The major alternative to substance dualism is "property dualism"--the view that mental phenomena are not physical per se, but that mental/spiritual experience is a property of certain physical interactions. In modern terms, one might call it an emergent property”
For me the notion of an “emergent property” in this sense is meaningless. The notion of an emergent property that would be meaningful to me is something like radioactivity for example. Radioactivity is a measurable and quantifiable property of radioactive elements. The fact is that there are a number of things that we hold as “real” that are outside the purview of “science.” So that is why I would personally favor substance dualism. Nonetheless there is no method I can think of that one could prove that substance dualism is true and that property dualism is false in the same sense that I can prove that water has a density of approximately 1 gram per milliliter.
Radioactivity is a property of structured physical matter, just as mental activity is a property of structured physical matter. Based on what you have said here, I get the impression that you are unfamiliar with chaos theory and the nature of systemic emergence, but maybe we just have a different understanding of that subject. Simple emergence can be understood in terms of the components of a system to the extent that we know the initial conditions of that system and can break its activity down into component interactions. That's why a
cellular automaton can be used to simulate emergence in a system of simple interactions. Reality itself, however, is vastly more complex than our simple models and recursively structured. That is, it consists of systems of systems. So you get different layers of emergence. It makes little sense to try to talk about emergent properties in terms of the properties of the components of a system. The properties of water molecules are very different from the properties of either hydrogen or oxygen, even though water molecules consist of those elements.
Anyway, I don't see how you go from a failure to imagine how mental activity can emerge from physical interactions to the belief that mental activity can exist independently of the physical activity it correlates with. It is hard to escape the observation that brains cause memories, emotions, calculations, consciousness, and bodily movements. Where do you leap from that observation to the claim that memories, emotions, and consciousness is likely to be a disembodied process?