Affordances and Design by Victor Kaptelinin explores affordances, indicators, usability, and utility at their very base level. It presents overviews of the different psychological theories underlying all interactions between people and their environments. It explains the differences between oft-conflated concepts like affordances versus indicators (important!), usability versus utility (just as important!), and how design can influence the relationships between them. With design so frequently being practiced only from the surface level, superficial conventions have a way of persisting and propagating. It can be helpful to take this kind of a dive to return to the fundamentals and rebuild from a sound foundation. It's not exactly a light read - unless academic texts are your beach books - but it's illuminating in a way that can give stronger roots to anyone's design perspective.