Chapter 4: “Knowing What to do: Constraints, Discoverability, and Feedback”

Hi & welcome! Thanks for joining in on my journey through “The Design of Everyday Things,” by Don Norman. This series summarizes and reviews each chapter, highlighting important takeaways and asking questions about the content.

Chapter 4 is full of advice for design. The last chapter focused on “knowledge in the head”, types of memory, and how we retrieve it. This chapter now journeys into “knowledge in the world;” specifically about how designers can use affordances, signifiers, constraints, and feedback to better provide support for users.

MAIN CHAPTER TAKEAWAYS

Section 1: Four Kinds of Constraints: Physical, Cultural, Semantic, and Logical

“Constraints are powerful clues, limiting the set of possible actions. The thoughtful use of constraints in design lets people readily determine the proper course of action, even in a novel situation.” — Don Norman

Physical Constraints

Cultural Constraints

Semantic Constraints

Logical Constraints

Cultural Norms, Conventions, and Standards

Conventions and cultural norms are a type of cultural constraint because they affect behavior. So conventions can definitely change over time, but they are “powerful tools” in shaping interaction with an object.

Section 2: Applying Affordances, Signifiers, and Constraints to Everyday Objects

“Failure to properly deploy these cues leads to problems.” — Don Norman

The Problem with Doors

Have you heard of Norman Doors? Essentially they are doors that have no clear indication of how to be used. Don Norman gripes a considerable amount (rightfully so) about the poor designs of such a simple concept, so he was given the honor of having the phenomenon named after him.

All we need, Norman states very clearly, to open a door is to know what to do and where to do it.

And yet, as a fast google will show you, there exist doors with no perceivable hinge, handles with instructions to push, automatic doors with no signifiers of the auto-intentions, and flat plates with instructions to pull. Madness.

The Problem with Switches

I don’t think there’s a “Norman Switch” — but another quick google will pull up images of light switch panels with no clear indication of what each switch actually controls. Here, Norman is arguing for what we discussed in Chapter 3, natural mapping.

Norman credits poor project coordination for the poor cohesiveness of light switch installations. Too many operators without insight into the function or ultimate need of the design. On top of this, the basic materials for creating well-mapped control switches aren’t available.

THOUGHTS: Poorly designed doors probably *also* result from poor project coordination. Someone orders “pretty” doors, the doors arrive, and the door installation person has no choice but to put hinges on the wrong side.

Activity-Centered Controls

Activity-centered controls are an alternative design to natural mapping. With activity-centered controls, all the controls for one action are in the same control panel. The switch for the video would dim the lights and turn on the video device. The switch for the speaker would dim some lights but keep some lights on the speaker.

THOUGHTS: Anyone who has a home automation setup knows the default mode you program is sometimes not the mode you actually want. Norman hints at this: whenever using activity-centered design, make sure to allow for customized switches as well.

He brings up a very good point in this section about physical light switches: physical protrusion is a very nice feature that will be missed if touch screens ever dominate the home automation scene.

Section 3: Constraints That Force the Desired Behavior

Forcing Functions

These functions are strong constraints that prevent the continued use of an object without certain steps being performed. This is excellent for the prevention of unwanted behavior that leads to harm, failure, or destruction. The next three subsections cover three types of safety methods that are forcing functions.

The trick to designing good forcing functions is to make them subtle enough not to cause great disruption from normal behavior (lest you want the user to hack a way around it and make the safety feature useless).

Interlocks

Lock-ins

Lockouts

Section 4: Conventions, Constraints, and Affordances

Flashback to affordances. There are affordances, perceived affordances, and signifiers. Not all affordances are perceivable. Signifiers are perceived affordances. They signify affordance. Don Norman has a bone to pick with designers who like to say “I added an affordance here” when they’re really talking about signifiers.

Conventions are Cultural Constraints

How does a user know how to interpret the signifier, though? Don Norman suggests this is largely due to conventions. He gives the example of a door knob on a door. We see it on the door and we know to turn it right.

This means conventions are a type of cultural constraint; limiting the options of operability.

When Conventions Change: The Case of Destination-Control Elevators

Change is hard. This section is an example of how hard it can be even when the change is beneficial, like in destination-controlled elevators. I had no idea these existed, but apparently were invented in 1985 and allow for faster passenger transport.

People’s Responses to Changes in Conventions

But why is change hard? Doesn’t everyone automatically see the new benefits of innovation and immediately want to take up the new way of doing things?

Of course not. Change means learning new things. Learning takes effort and it takes time.

Regardless of the potential benefits of new innovation, paying homage to conventions in your design will aid the transition to the new technology. Don Norman doesn’t suggest this, but files on computers are perfect examples. A conventional conceptual model eased the use (and pick up) of computer directories.

Section 5: The Faucet: A Case History of Design

Adding faucets to the list of items Don Norman can really get in-depth about! Here we have a long, broad dive into the design complications of the simple faucet.

It has two things people care about: temperature and flow rate. Yet, designs abound that don’t show affordances, aren’t discoverable, and don’t provide feedback.

I found the last portion of this section interesting and relatable:

“Standardization is indeed the fundamental principle of desperation: when no other solution appears possible, simply design everything the same way, so people only have to learn once.” — Don Norman

It’s interesting because standardization and design/innovation feel contradictory (although I acknowledge they aren’t mutually exclusive). Maybe the faucet is just a bad design overall and isn’t getting to the root cause (clean hands and body). Maybe faucets have already reached their optimal design? Does this mean objects can reach an innovation-dead-end? Then we standardize or completely back up and reproach the requirements/root cause.

Section 6: Using Sounds as Signifiers

One of my favorite sections from Chapter 3 was about distraction and using different sensory modalities to deliver information in a non-invasive, distractible way. Sound delivery is one such modality.

Sound also provides nuanced information. A screen can tell me a device is broken, but to hear the broken device is a completely different emotional and visceral experience. Sound can provide information about distance. Sound can soothe and provide a mood. I personally love sound as a reminder.

But also, think about the lack of sound. When an object *doesn’t* make sounds, we’re left befuddled or unsure about the state of the object. Did it change? Is it done? Do I press again? Sound clears up this ambiguity

When Silence Kills

The absence of sound is a large topic in the field of electric vehicles. These machines make such little sound when they operate that pedestrians can’t hear them.

At first blush, no car sounds seem great. But then I realize all the times I’ve been warned by the sound of a car approaching when playing or walking near a street. Being able to hear cars is also crucial for people who are blind.

One solution they have is making these new, quiet machines have fake car sounds. They are mimicking the old. Skeuomorphic “is the technical term for incorporating old, familiar ideas into new technologies, even though they no longer play a functional role.”

Don Norman uses this example to highlight the need of using convention and standardization in design as a safety precaution and aid for adopting new technology.