The Dunce Cap was invented by the Scotsman John Duns Scotus around 1300 AD. He felt it could help the wearer to focus attention on the lesson. It was scientific, or very nearly.
More recently, the Dunce Cap has denoted ignorance or social transgression. It is not often used Today; there are Modern Ways to humiliate and alienate students.
John Duns Scotus died today in 1308, a great teacher and churchman. He was made a saint in 1993. No rush.