Sunday, August 28, 2011

Bad nudging at the toilet

By Pelle Guldborg Hansen (tip from Rasmus Rendsvig)

I've always found toilets to be fascinating. While the public square is the paradigm example of a public space - the architectural principle for auto-generating common knowledge and thus of crucial political importance - toilets are the paradigm example of a private space. This makes public toilets a particulary interesting topic in itself - but nudging at the toliet an even more interesting one.

There are many bad nudges out there. This particular one has puzzled me several times - and now Rasmus Rendsvig has provided the photo-documentation that proofs my suspicion.

As we all know, the effort to save water has led to new designs and systems for flushing the toilet. One of the most widespread ideas for saving water is the introduction of a choice between "the big flush" and "the small flush".

But how do you design the flushing button to convey this choice in a way that is easily understood? Not like this!

The problem is that, while the big button might seem to signal "big flush" and the small one "small flush", there are also strong associations running in the other direction.

Since nature has it that "small flush" is the one to be used most frequently it seems just as natural to associate the size of the two buttons with the frequency with which they are to be used. Hence, the big button may also signal "small flush" and the small one "big flush"!

So which set of associations wins out? This cannot be decided on matters of principle. Rasmus' pictures on the other hand, show what to my mind prevails in practice. Granting that the hypothesis about the frequencies called for by nature is true, the wear and tear suggests that the associations based on frequency wins.

But does this mean that as a result an awful lot of water is wasted? Well, I don't know, since I can't figure out what happens when you push the big button! Big flush or small flush?

Please go to a nearby toilet, check it out and report back.


  1. What about urinals... If this picture is from a mens room then most peeing people would probably use the urinals..

  2. Good point! But according to the skilled photographer, there were no urinals at the mens room.