It is hard to believe that an everyday water faucet could need an instruction manual.
  ~ Donald Norman, 1988, p. 166

Searching for the "zipless fuck," Erica Jong toured Europe and discovered some lessons in diversity. One had to do with toilets. In a psychoanalytically inspired meditation on the (then classic) design of German toilets, Jong inferred features of latent national sexuality that depend on, shall we say, certain olfactory experiences afforded by the hardware. If you find this brief description of her adventure tantalizingly ambiguous, consult her novel "Fear of flying" for the lowdown.

From time to time I tour Europe and Germany in particular, and I have also come upon episodes of diversity. It is trivial to say that Europe is more diverse than the United States. Obviously, the old continent has a far greater variety of languages, cultures, and cuisines than the U.S. I recall with a shudder the raw minced pork sandwich popular in the lower Rhine area. This difference in diversity is, in part, the result of the iron law of colonization. Colonization homogenizes, especially when it wipes out native populations. This law need not be a stick to shake at people; it is more general than human responsibility. Genetic diversity within and across species increases with the number of generations having lived in a location. Africa has far greater genetic diversity than continents that were colonized later. Areas vacated by ice after the last eponymous age have only a fraction of the number of species that tropical regions have.

My recent confrontation with European diversity occurred in bathrooms (and that's where Erica J. comes in). The triggering stimuli were showers rather than toilets (more on those later). I already knew that European hotels are fantastically diverse. Most of them have an individual appearance and "feel,' which is marvelous for memory. You can remember where you stayed, and call up associated memories by recalling the hotel. Try that in a country where they all look alike. Each snowflake may be unique . . . but who cares.

My story begins in a mom-and-pop hotel in the west end of Frankfurt. There I spent my first jet-lagged night and I have no idea how I got into and out of the shower and into bed. And that's the beauty of it. The non-event was significant. The dog did not bark, dear Watson. The next day and a ride on the ever-delayed Deutsche Bahn later, I arrived in the Dutch town of Groningen (read: "KKHHRRoningen"). My gentle hosts at the Department of Psychology had booked a room for me at a beautiful "boutique hotel." I was unfamiliar with the concept, but loved the place. . . until I ventured into the shower.

When I saw the fixtures, I knew I was in trouble. The shower had two dials arranged along a vertical plane. Both had levers sticking out to the East (or 3 o'clock). I did not notice explanatory labels at the time. Violating the basics of hypothesis testing, I started to turn both levers at once, becoming convinced that the top produced hot water as I moved it counterclockwise, whereas the bottom produced cold water with clockwise motion.

I worked out a comfortable spray of reassuring temperature. My jetlag-addled brain re-entered panic mode when I realized that I needed to turn the water off without getting scalded or iced. Would I remember to turn both levers in opposite directions (but which)? Somehow it worked out, but I attribute that to dumb luck (or the magic of the smart unconscious, which knows more than I do). The fixture design, beautiful and elegant as it was in a boutique kind of way, was a terror from the psychological point of view. Why?

Appliances, fixtures, and other devices operated by humans ought to be designed to minimize errors. They are not supposed to test the operators' intelligence with the objective to separate the smart from the dumb. Error minimization is achieved by making handling intuitive, and intuitive handling is achieved by simplicity, respect for expectations, and a mapping of operations on functions.

The Groningen fixtures were not simple. There were two controls when one would have been enough. When I returned to the mom-and-pop hotel in Frankfurt, I realized why my shower experience there was so pleasantly uneventful. There was one control that a single hand could manipulate to give more (by pulling up) and hotter (by pushing left) water. The Groningen fixtures did not meet expectations. Most people expect hot and cold to be spatially arranged from left to right. Most people also expect to see a clear resting, or zero, position, which the Groningen fixtures did not provide. Finally, the fixtures did not map operations well on functions. As it turned out, the top fixture controlled water volume, whereas the bottom controlled temperature, i.e., the visually identical fixtures had entirely different effects depending on location.

On the second day, I found tiny marks indicating function. There was a colorless < sign for more water on the top lever; and there was a blue > sign on the right and a red < sign on the left of the lower lever. These marks were barely visible by looking down and they were not both visible at the same time. At least the color codes checked out, but they have to stare the operator in the face to be effective.

And then there were the stopping knobs. After a 90-degree rotation, the levers hit a point of resistance, which could be overcome by depressing the knobs. I could get more and hotter water if I really wanted to, but only by deliberately overriding the physical expression of environmental conscience.

Good design is consistent. The bathroom's sink fixtures were of the same stylish design, but now cold (on right) and hot (left) water were controlled by separate levers, which is what I had first expected to the be case in the shower. Now, the sink's cold-water fixture had to be turned clockwise, whereas the hot-water fixture had to be turned counterclockwise.

A few days later, after several mindless (in the good sense of the word) showers in the mom-and-pop hotel, I came upon another variant of beautiful-yet-bamboozling fixture design. Checking into a hotel in Köln, I immediately noticed that the Grohe company, which makes these showers, had prepared another challenge. The fixture was a horizontally extended bar with rounded ends. Each end could be turned toward me or away from me, but what would it do? Not simple, no respect for expectations, no mapping. Experimentation revealed that the right bar controlled volume and that the left bar controlled temperature. I do not remember which direction either end needed to be turned, though. Again, there were additional knobs that needed to be depressed if I wanted to proceed into the ecologically incorrect range.

When I later shared my experience with the receptionist, she said that guests often call her office in desperation, asking for help with shower operation. This should not happen. Shower controls can and should be designed in such a way that the tired, the jet-lagged, and the drunk can operate them without thinking. But, as the saying goes: "Why make it simple when you can make it complicated?"


Back in the USA, confusing shower fixtures may be found as well. Truly, there are limitless opportunities to violate the simple principles of good human factor design. In my own bathroom I have what I after limited sampling suspect to be a design that is rather common in this country. There is a two-part fixture that operates the shower and the bathtub tap. The upper part is a dial with a resting position at 1 o'clock. As you turn counterclockwise the water is released at full volume (well, that also depends on the setting of the second part of the fixture; see below). As you continue to move counterclockwise only temperature is affected. You move through the cold area and the warm area to the hot area, which ends at about 1 o'clock. In other words, this dial conflates two operations: (1) water: go - no-go and (2) temperature. You must go through cold before you can get to warm. The lower part of the fixture is a sliding lever. At the leftmost setting, it directs water to the tub at full force (if the upper dial has been turned to ‘go'). As you move right, the volume of water is reduced, coming to a near standstill to then pick up again but coming out of the showerhead. Again, this part of the fixture conflates two operations: (1) tub v. shower and (2) water pressure. The best the showerer can do is to make sure the slider is set to tub, turn the dial fast toward warm, find the desired temperature, and then move the slider toward shower. The dismay of first getting a blast of cold water (which has still been sitting in the pipe feeding the shower) never quite goes away.

Bergamo, June 2011

Here's another example of my thesis that non-chain hotels are a great introduction to European cultural diversity and the madness of shower design. I spent 3 nights in a fantastic boutique hotel in the beautiful Città Alta of Bergamo. The hotel was recently refurbished; the structure of the building itself went back to a 13th Century defensive tower. Weary from a long day (I got up at 5:00 a.m. in Madrid, flew to Munich, and crossed the Alps by car), I stepped into the shower. I was happy to see a hand-holdable shower and a fixture of the desired one-grip design. The problem was there were two (2) of them! Why, oh why? If one one-grip shower fixture is a good idea, two does not seem to be. Then I made the experimentalist's cardinal mistake (again!): I started to manipulate two controls at the same time. So much for the experimental commandment of varying one thing while holding everything else constant. But then again, as I asserted earlier, travel-weary hotel guests are not compos mentis. I suspect that the psychological source of the "start moving several things simultaneously" heuristic is the not entirely demented idea that you can hedge your bets against getting scalded or iced. What happened next was a surprise (of course it was). Water came at my from the moveable showerhead in front of me (which was expected), but also from straight above. Looking up I realized that a second showerhead was mounted on the ceiling. So they were giving me options, which I appreciated. In hindsight, I would have only wished that the two grip control were arranged in vertical order to represent the spatial order of the fixtures. Mapping problems seem to be hard for designers.

After all this kvetching about compromised designs, let us also acknowledge that progress has been made. Growing up in Germany, I remember battling many a sink with separate taps for cold and hot water (see pic). A trusted colleague tells me that this divide-and-frustrate strategy lives on in parts of the United Kingdom. What does not kill you . . .

Austin, TX, 2012

The is a general tendency among designers to make things automated because they can, not because they must. In our psychology building at Brown University, the bathroom sinks ask you to move your hands to and fro under the faucet to get water (they call this automatic, but you still need to move, so it is perhaps better called touchless), whereas you need to press down on the soap dispenser to dispense soap. In a convention hotel in Austin, TX, I observed the opposite -- with unintended consequences. You move your hand to and fro under the soap dispenser to dispense soap (automatically) and then turn on separate hot and cold taps to get water. The soap dispenser is a bit off to the right of the faucet. As you move your hands under the faucet to clean your skin with the earlier dispensed soap, more soap is being dispensed because you are moving your hands. In fact, the soap is squirted on your right cuffs or thereabouts. You don't need a focus group to get this right, do you?

Niederdürenbach, Germany, December 2012

In a small Landhotel, barely 20 miles away from where Indiana Jones battled the Nazis at Grunewald Castle -- the actual Schloss Bürresheim -- a back-assward fixture presents itself. Whereas the right switch controls water valume, the left switch controls water temperature, sort of. The numbers indicating degrees Celsius are crisply visible to anyone immured behind the shower. To the actual shower taker, the numbers stand on their head. He must perform a 180 degree mental rotation, the kind of exercise not welcomed by the weary traveler. Even though I was rather ebriated ( = not inebriated) that night, I got iced and scalded, and then scalded again. Thank god I don't champion noncompensatory decision rules. I would visit this place again for the home-made apple juice, free of charge.

Reutte, Austria, March 2013

The struggle continues. Volume and temperature. Let them be controlled. Must it be so hard? Here, in a wonderful, family-run 3* hotel, the shower manifests with two controls. The top one is unlabeled and one deduces that it must be for volume because the lower one has a red knob sticking out, which is a common heat symbol. As you turn the lower dial clockwise, the water -- if you have turned the top dial clockwise -- will become warmer. Readable numbers indicate the temperature in degrees celsius. The red knob, and here is the rub, will become significant when you can't see it any more. When it is under the dial, facing south, it will bar any further turn toward greater heat. Unless you depress it, that is. You can get greater heat by making the heat symbol, which is already out of view, invisible [by pressing it into the black dial. I learned this from dabbling and razor-sharp deduction. I will now take an actual shower.

In other posts, I consider the psychology of toilets and urinals, car locks, and stovetops.

A book-length treatment of these sorts of issues can be found in

Norman, D. A. (1988). The psychology of everyday things. New York: Basic Books.

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