Pretty much the only thing I remember from my human machine interaction class aeons ago is a discussion of text vs. pictograms vs. abstract icons. Text is clearest but takes the longest time for experienced users to find what they are looking for. Abstract icons are unclear to new, untrained users but are super fast to find/discern by experienced users. Pictograms are a compromise.

Related: US traffic signs always bothered me because we have trained users who need to be able to identify the traffic signs as quickly as possible so that they can focus on the road. Yet we use traffic signs that are optimized for the opposite use case. Europe and most other countries are way ahead on that.