When I parked my car at a Park and Ride this summer in Kent, I saw this sign. My first thought was “Whisfull thinking of the city planners to warn about deers”. Only when I saw that there were a dozen of these signs I understood that it wasn't a warning but an indicator for where I parked. I saw that another area of the parking space had a realistic wolf. This is where someone didn't understand how pictograms / metaphors should work, they should be abstract and translate the environment towards the reality, indicate your space or actions via something else so one can predict what the result of the action should be or for example where one is. When I see a traffic sign of deer, I don't think “I parked in the deer section”. I think -stupid as it may sound- be careful when parking there are deers here.

Take for example the pictograms for the parking lot of Schiphol Airport, worldwide known for the best use of abstract pictograms and metaphors. What the London tube did for abstract maps, Schiphol did for icons. Clear abstract pictograms. Not drawn to resemble traffic signs and thereby confuse the reader but the Schiphol icons are clearly an indicator by themselves. All in the same language, pictograms of what foreigners think as “Typical Dutch”, wooden shoes, tulips, windmills etc. Borrowing from that was is good for the purpose of the objects but not steeling bad metaphors like a traffic sign with a red border generally associated with “forbidden”, not like blue sign that is associated with “information”

What you can learn from this if you use graphical metaphors IRL or in an application.

1. Think about what you want to say
2. Think about how you want to say this
3. Think about how someone else will and can read this
4. and do hire a designer :-)