Would you have designed it that way?

In my day-to-day life, I often think about design problems as I encounter them. I find myself wondering about information that I don’t have—details that would help me solve the problem I noticed. And I wonder: faced with the same constraints, would I have come up with the same solution? Here’s one I encountered.

Passengers waiting to board a ferryLast week, some friends wanted to visit their family on an island. Where I live, people use ferries to get to travel between various islands and the mainland. At times, I’ve made the crossing on foot, by bus, or by passenger car. The choice might depend on the size of our group, how far we’re going on the other side, how much we want to spend, what time of day and year we’re travelling. On busy days the ferries fill to capacity, and traffic reports may announce “a 1- or 2-sailing wait” between points. From time to time the media discusses changes to ferry service, prices, and ridership. All in all, there are a lot of factors influencing the deceptively simple question: “When I get to the ferry, will there be space for me on board?” The question could also be: “Can I avoid waiting in line?”

The ferry company’s website answers this question in a seemingly fragmented way, and that got me thinking: why was the answer fragmented, and what user needs was the website’s current design meeting? The ferry company segments its audience by mode of travel. This segmentation is logical for an audience motivated by cost, because a ferry passenger on foot pays less than a ferry passenger in a car. But when other decision-making factors are more important than price—such as space availability—segmenting users by mode of travel might not be helpful.

Can I avoid waiting?

The friends I mentioned earlier had all the time in the world to get to their family on the island. But they didn’t want to wait in line for hours. Finding the answer to “is there space for us, or will we have to wait” is complicated because the answers seem to be organized by mode of travel on different pages of the website. Here’s a reproduction of one of the first “is there space for me” answers I found on the website:

Is there space on the ferry?

Given the question, the above screen may not be clear. What is deck space? And—look closely at the orange bar—how much deck space is available? Is it zero or 100%? Is a reservation the same thing as a ticket? Does everyone require a reservation to board?

Here’s another way to present the same information, this time making it clearer that a driver’s willingness to pay more may influence wait time:

No reserved spaces on the ferry

Now it’s clear that this information about availability only applies to vehicles that want a reservation. That means foot passengers, bus passengers, and cyclists still don’t have an answer to the “will we have to wait” question. From experience, frequent travellers already know part of the answer: passengers on foot almost never have to wait, but occasional travellers and tourists wouldn’t know this. And travellers with vehicles may wonder about alternatives, because leaving the car on shore and boarding on foot could put them on an earlier ferry. The answer to “can we avoid waiting” may require a comparison of wait times for each mode of travel.

Here’s another way to present the information, this time listing more modes of travel:

Different types of space on the ferry

The above screen answers the “can we avoid waiting” question more clearly. In addition to providing greater certainty for some modes of travel, it also meets the (presumed) business need of generating revenue by selling reservations.

Design questions, but no answers

It’s easy to theoretically “solve” a design problem that we encounter, but there are always unknowns.

  • Is there really a design problem? How would we know?
  • Would this design have been technically possible?
  • Would this design have been affordable?
  • Would this design have met the needs of many users, or only a few?
  • Would this design have been ill received by customers or interested groups?
  • and so on….

So if you can’t know all the answers, why bother with the exercise? Because it’s what we do, in our line of work.

The trigger for this exercise

Here’s an excerpt of the screen that inspired this post.

Excerpt of the original screen

Reduce spam without hindering usability

If your website lets visitors sign up, join in, add comments, or enter reviews, then—in addition to the legitimate details you want—you’re getting some garbage. Some of this garbage is sent by automated spam-bots.

You can reduce the unwanted entries that your website generates, but consider who pays the price to ensure your business’ data is clean. Does your business pay? …Or do your legitimate site visitors pay? Continue reading “Reduce spam without hindering usability”

When a user interface is for using—not for understanding—a product

The purpose of a user interface is not to explain how a product works. Instead, the interface is to help people use the product. Here’s an idea: if someone can use your product without understanding how it works, that’s probably just fine.

What model does the user interface reflect?

Models are useful to help people make sense of ideas and things.

An implementation model is how engineers and software developers think of the thing they’re building. It helps them to understand the product’s inner workings, the sum of its software algorithms and physical components. For example, a car mechanic has an implementation model of combustion engines.

A mental model is how someone believes a product behaves when they interact with it. It helps them to understand how to use the product. For example, a typical car driver has an implementation model of pressing the gas pedal to go faster and pressing the brake to slow down. This mental model doesn’t reflect how the car is built—there are many parts between the gas pedal and its spinning tires that typical drivers don’t know about.

The implementation model and the mental model can be very similar. For example, the mental model of using a wood saw is that “The saw makes a cut when I drags it back and forth across the wood.” This overlaps with the implementation model. In addition to the back-and-forth user action, the implementation model also includes an understanding of how the saw’s two rows of cutting edges—one for the forward stroke and one for the backward stroke—help to cut the wood fibers, break the cut fibers loose, and then remove the fibers from the kerf, and whether the saw’s tooth shape is better for cutting fresh wood or dried wood.

The mental- and implementation models can overlap, or not

The implementation model and the mental model can also be very different. Let’s consider another example: getting off a public-transit bus. The mental model of opening the exit doors is that “When the bus stops, I give the doors a nudge and then the doors open fully.” The implementation model of the exit doors is that, once the bus stops and the driver enables the mechanism, the exit doors will open when a passenger triggers a sensor. Now consider this: if the sensor is a touch sensor then the passenger’s mental model of “nudging the door” is correct. But, in fact, the sensor is a photoelectric sensor—a beam of light—and the passenger’s mental model of “nudging the door” is incorrect.

To exit, break the photoelectric beam

Getting bus passengers to break the photoelectric beam was a real-life design challenge that was solved in different ways. In Calgary, public-transit buses use a large, complex sign on exit doors to present a mental model that’s somewhat consistent with the implementation model:

Signage explains the complex implementation modelTO Signage for a simpler mental modelOPEN THE DOOR

      1. WAIT FOR GREEN LIGHT
      2. WAVE HAND NEAR DOOR HERE

In Vancouver, public-transit buses use a large, simple sign on exit doors to present a mental model that’s inconsistent with the implementation model:

TOUCH HERE ▓ TO OPEN

In fact, touch does not open the exit doors at all—not on the Vancouver buses or the Calgary buses I observed. Only when a passenger breaks the photoelectric beam will the doors open. In Calgary passengers are told to wave a hand near the door. A Calgary bus passenger might conclude that the exit door has a motion sensor (partly true) or a proximity sensor (not true).  In Vancouver passengers are told to touch a target, and the touch target is positioned so the passenger will break the photoelectric sensor beam when reaching for the target. A Vancouver bus passenger might conclude that the exit door has a touch sensor (not true).

Calgary bus passengers are more likely to guess correctly how the exit door actually works because the sign presents a mental model that partly overlaps the implementation model: the door detects hand-waving. But does that make it easier for someone without prior experience to exit the bus?

No, it’s harder.

It’s more difficult for a sign to get passengers to hold up a hand in the air in front of the door than it is to put a hand on the door. Here’s why: If you knew nothing about a door that you wanted to open outward, would you place a hand on the door and push? Or would you wave at it? From our lifelong experience with doors we know to push them open. Touching a door is more intuitive than waving at it, and that’s why “nudge the door” is a better mental model and thus an easier behaviour to elicit and train. The simpler mental model improves usability.

Rule of thumb for mental models

When understanding of a product’s inner workings are unnecessary, staying true to the implementation model risks increasing the complexity of the user interface. Instead, have the user interface, reflect a mental model that is simple, effective, and usable.

If you can relate the use of an object to a common experience or simple idea then do so—even if it doesn’t follow the implementation model. It is unnecessary for a system’s user interface to convey how the product was built. The user interface only needs to help users to succeed at their tasks.

No doubt there are cases where a lack of understanding of a product’s inner workings could cause danger to life and limb, or cause unintended destruction of property. In that case, the mental model needs to convey the danger or risk or, failing that, needs to overlap more with the implementation model.