When the whole university is celebrating the end of the 251st academic year of our university and another graduating class, there have been, among my colleagues, some discussions (during lunches) on academic regalia.
As a graduate from Columbia myself, I naturally took what I went through as the "right" way of doing it and only was surprised to find out the ceremony may go quite differently in some other institutions. Of course, different universities have different colors for their gowns. I am not referring to this colorful side of the academia. What surprised me was how casual Columbia's Ph.D. convocation appeared to be, comparing to some other universities. My colleagues from other university seem to have a much better idea of the traditions. According to them, the hood is a big deal, symbolically. For example, one said that only those who had an academic position after graduation can wear the hood. Another said that the hood can only be wore after the degree was conferred (thus after the convocation). There are even some hooding ceremonies in some places, where the phd advisors will put the hood on to his/her proteges. I was nearly disappointed by the fact that I had such a unrecognizing graduation to end my long graduate study. It could even be that I had had a wrong doctoral convocation!
Now I recall how clueless I was when trying on my doctoral gown, hood and cap in the lady's room of Low Library. In a small space full of recently earned female phds, there are so many different ways in which the academic regalia were put on. I remember I asked a person next to me on how to put on the cap, and she simply shrugged saying she had no idea. Anyhow, I am at peace since I quite enjoyed my convocation quite well.
As a researcher, one should do research on things they are curious about. So I did some research on academic regalia and found (at least) that not all in a doctoral gown need to be a doctoral degree holder but only those who have a real doctoral degree can wear a hood. It is, however, not necessary for the hood wearer to have any academic appointment. Sure, this random website I found could also be wrong.
"The traditional rule is that a candidate for a degree should not wear the hood of that degree until it is actually conferred. This rule still applies to those who are to be individually hooded during the commencement ceremony; they should not wear the hoods in the preliminary academic procession. However, when degrees are to be conferred en masse, without individual hooding, the groups involved, e.g., master's degree candidates at large universities, may wear their hoods in the preliminary procession and throughout the ceremony."