When Double-Sided Signs Have Single-Sided Meanings02 Nov 2009
On a recent visit to my local supermarket, I selected a few items and approached the till. A sign at one end of the queue partition read Queue Here so I waited there for the customer in front to finish their purchase. When I moved towards the till, the server informed me that there was a queue and I should join the end. I pointed out the sign but was met with a blank look from the server and some not-so-blank looks from the other customers. In fact, these other customers did form a queue. What went wrong with such a simple interaction?
When I joined the end of the queue I noticed that the other side of the sign also read Queue Here. The reason for the sign is clear—to shepherd customers into a tidy queue—but the message of the sign is clear in only a single case, which is when the queue is empty. The sign is correct when the queue is empty because the head of a queue of one is always in the right place, whichever side of the sign that person queues.
Standing on the correct side of the sign only becomes important as more people join the queue. As soon as one person joins the queue, one side of the double-sided sign becomes redundant and misleading. A design rule for signs is that they should always apply to the people looking at them. If a sign has only a single-sided meaning, it should have a caption on only one side.