I've only encountered posters once at an academic conference, the SHARP book history conference at the Bibliothèque Nationale de France. Posters aren't generally a thing at humanities conferences, so this was a new experience for me! Though more familiar to Martin who was with me that day. I had to drop out of my CS PhD too soon before running into them at science conferences. We did manage to speak to some of the people at the Paris poster session, but spent much of our time photographing pictures, and especially using Google Translate app to translate the ones in French!