Clear and effective visual controls need to alert the viewer of normal versus abnormal conditions and/or provide guidance towards acting in accordance to the norm or standard. The street sign above is provided by the Tokyo metropolitan police department. The purpose is to inform people in advance of a major earthquake to not use this road, as it will be closed and its use limited to emergency vehicles.
There are many ambiguities in this sign.
First, while it is called an “emergency road” the sign indicates that during an emergency this will not be a usable road. Unlike an “emergency exit” which is the go-to exit in case of emergency, this is the no-go road in case of earthquake. When we use the same term to mean opposite things, the result is not clarity. If the meaning is “for use by police and emergency vehicles only” then words to that effect would be far less ambiguous. While the Japanese text says that the road is closed to non-emergency vehicles, the English is vague in that regard.
Second, the closure is in case of a “major earthquake”. What is considered major? There is hardly anything worse than ambiguity or lack of information when it comes to disasters. People want to take action, help, or stay out of the way but cannot until they know how to act based on whether the event is major or minor. In Japan there are many earthquakes that are too small to be notice, let alone require action. To a foreign visitor who has never experienced an earthquake, a 5 or 6 may feel major, when in most cases a 5 or 6 is not severe unless they are inland and originating close to the surface. The Japanese does not specify “major earthquake” at all, but simply states “in the case of earthquake disaster”. While “disaster” is still vague, it is more precise and less subjective description than “major”.
Third, what’s the deal with the cartoon of the blue fish? It is attention-getting, prominent and pregnant with meaning. A driver who is not paying attention to the writing may simply think this sign leads the way to the aquarium, fish market or a waterway. Visual controls that contain standards based on artifacts of cultural assumptions shared by members of that group are inherently ambiguous to outsiders of that group. The cartoon is of a catfish. In Japanese mythology there is a giant catfish underground which causes earthquakes when the god keeping it in check lets down his guard. There is also a related traditional belief that catfish can predict earthquakes. There are stories of catfish in a pond behaving unusually immediately before an earthquake. There are stories worldwide of other animals sensing earthquakes before humans, but the catfish as earthquake predictor is a cultural artifact unique to Japan. Any child in Japan would associate a catfish with earthquakes, so why not foreign adults?
The trap that the Tokyo metropolitan authorities fell into in creating this visual control is in assuming that their assumptions are shared those who view the sign. In fact, it is most likely that they were not even aware that they were making an assumption about their assumptions. It is possible that there was never any question that one’s assumptions are shared by others. This type of meta-assumption is quite dangerous; it limits communication, erodes the effectiveness of visual controls, and causes misunderstandings between cultures worldwide. Ambiguous visual controls are just one way that we can surface these assumptions, but we must find other ways in order to bring about mutual understanding. This is essential for the maintenance of standards and continuous improvement.