The British Burgon Society studies the history of academic dress with an aim to study, preserve and advise on all aspects of practice of wearing caps and gowns. Alex Kerr, an expert on the subject, has posted an article Layer upon Layer: The Evolution of Cassock, Gown, Habit and Hood as Academic Dress.
The article, written in 2006, discusses misconceptions about the use and significance of the various articles of academic clothing worn in the Middle Ages.
Alex Kerr writes:
If we can identify the various articles of academic dress in the late Middle Ages and how they were worn together in layers, I believe it will be easier to understand how they evolved into the garments in use today. We shall see that each of these articles remains within the particular category of garments to which it belongs (cassock, gown, habit or hood), although it may alter significantly in appearance over the centuries. Each category of garments forms a distinct layer in the medieval and early modern periods: articles do not migrate from one layer to another, and the order in which the layers are worn does not change.