Phenomenal holism is the proposition that an experience is defined not by its intrinsic properties but by its relationship to other experiences a subject could possess. The proposition bears a striking resemblance to the Yoneda lemma in category theory, a statement showing that any object in a category is defined by its relationship to all the other objects in that category. Inspired by these ideas, we have obtained preliminary empirical support for using this framework to characterise phenomenology. Specifically, we have shown that colour experiences across the visual field are equivalent through capturing the subjective similarity relationships between these experiences at different locations. Nonetheless, theoretical concerns remain around how this approach can respond to the 'inverted qualia' thought experiments. A specific worry is that if experiences are not defined intrinsically, it seems that specific experiences can become unbound from the substrate upon which they supervene. We will explore potential solutions to this problem that do not entail eliminativism. Ultimately, development of this framework will help in verification of the neurophenomenal structuralism hypothesis, which holds that the relationships between neural correlates of consciousness should structurally resemble their phenomenological counterparts.