Thick subjectivity would be subjectivity imbued with all the dimensions of generalised qualia, while thin subjectivity would only possess qualia in the ordinary sense, the sense of what an experience is 'like', or rather the fact of the experience being 'like' something. But thick subjectivity is largely gone from the world; we seek it in art and in deep experiences, but as an object of desire, as a formal desideratum, it has become delimited, you might even say commodified. It puts down no deep roots, is ready at any moment to be superseded by the next such experience, and in addition it is sufficiently defined to form a token in games of social status. This is something like the evaporation of values from the moment they are grasped as values. This is not something you can necessarily stand back from and witness, it has effects all the way down to the roots of consciousness. Whatever you undertake in the way of enquiry, it is not you asking the questions but your entire situation, and this is exactly how it ought to be.