You’ve been there. You walk up to a beautiful glass door at a high-end office or a trendy cafe, you see a vertical handle, and you pull. It doesn't budge. You pull harder. Nothing. Then you notice the tiny, faded "PUSH" sticker. You feel like an idiot, right?
Don Norman says you aren't the idiot. The door is.
That specific frustration—the "Norman Door"—is the cornerstone of his seminal work, The Design of Everyday Things. Originally published in 1988 as The Psychology of Everyday Things (POET), the book changed how we look at the world. It’s the reason why your favorite apps feel "intuitive" and why your stove’s burner knobs might still drive you crazy. Honestly, it’s probably the most influential book in the history of User Experience (UX) design, but it’s really about how humans think.
The Core Concepts People Usually Get Wrong
Most people think "design" means making things look pretty. Norman argues that design is actually a form of communication. When a product is designed well, the person using it knows exactly what to do without a manual.
Take "affordances." This is a term Norman borrowed from the psychologist James J. Gibson, but he tweaked it for the world of objects. An affordance is a relationship. It’s what an object allows you to do. A flat plate on a door "affords" pushing. A knob "affords" turning. If you see a chair, it "affords" sitting.
Problems arise when the perceived affordance doesn't match the actual function. This is where "signifiers" come in.
Signifiers are the signals. They are the "Push" signs, the arrows on a touchscreen, or the way a button is raised to look like it should be clicked. Norman later clarified—to the relief of many confused designers—that while affordances are the possibilities, signifiers are the cues that tell us how to act. If you need a sign to tell people how to use a door, the design has failed. It’s that simple.
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The Seven Stages of Action and Why We Fail
Ever tried to set the clock on a microwave and ended up accidentally defrosting a pound of ground beef? Norman explains this through the "Gulf of Execution" and the "Gulf of Evaluation."
- The Gulf of Execution: You want to do something, but you can’t figure out how the machine works.
- The Gulf of Evaluation: You did something, but you have no idea if it worked.
He breaks this down into a seven-stage cycle. You start with a goal. You form an intention. You specify an action. You execute. Then, you perceive the state of the world, interpret it, and evaluate the outcome.
It sounds academic. It’s not.
Think about a light switch. You want light (Goal). You decide to flip the switch (Intention/Action). You flip it (Execute). The light comes on (Perceive/Interpret). You’re happy (Evaluate).
But what if there are ten switches in a row? Suddenly, the "Mapping" is broken. Mapping is the relationship between controls and their effects. In a perfect world, the layout of the switches would match the layout of the lights in the room. When they don't, you spend your life flipping three different toggles just to turn on the kitchen pendant.
Human Error is Actually a Design Error
Norman is famous for his stance on "human error." He hates the term.
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In the book, he recounts several stories of major disasters—like Three Mile Island—where "human error" was blamed. But when you look at the control rooms, they were designed in a way that made mistakes inevitable. If two identical levers do opposite things and are placed right next to each other, someone will eventually pull the wrong one. That’s not a bad employee; that’s a bad designer.
We have two types of "errors" according to Norman: Slips and Mistakes.
- Slips happen when you intend to do one thing but do another (like putting the milk in the cupboard and the cereal in the fridge). These are usually caused by a lack of attention or being "on autopilot."
- Mistakes happen when your mental model is wrong. You think the thermostat works like a gas pedal—that turning it to 90 degrees will heat the room faster. It won't. It's just a binary switch. That’s a mistake based on a flawed understanding of the system.
Good design accounts for both. It uses "constraints" to prevent you from making slips. Think about how a modern car won't let you shift into Reverse while you're going 60 mph on the highway. That’s a physical constraint saving you from a lethal slip.
The Feedback Loop
Feedback is the most basic requirement of a good system. It’s the "click" when you plug in a charger. It’s the "whoosh" sound when you send an email.
Without feedback, we get anxious. We press the elevator button five times because we aren't sure it registered the first press. In The Design of Everyday Things, Norman emphasizes that feedback must be immediate and informative. Too much feedback, like a car that beeps at you for every minor thing, becomes "noise" and gets ignored. It’s a delicate balance.
Conceptual Models: How We Think Things Work
Everything we use, we have a mental model for. You have a mental model of how a smartphone works, even if you don't understand the circuitry. You have a model for how a faucet works.
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Designers have their own "Design Model." They know exactly how the product works. Then there is the "System Image"—the physical object itself, the manual, the branding. The user builds their "User's Model" based solely on that System Image.
If the designer’s model and the user’s model don't align? Frustration. Total chaos.
This is why "Skeuomorphism" was so big in early iPhone days. The Notes app looked like a yellow legal pad because Apple wanted to tap into your existing mental model of what a notebook does. Now that we’re all tech-literate, we don't need the fake paper texture anymore, but it was a bridge to help us build a new conceptual model.
Putting It Into Practice: How to Stop Designing Bad Stuff
If you're a creator, an engineer, or just someone who wants to complain more effectively about your smart home setup, Norman’s principles are actionable.
- Visibility: Can the user see the state of the device and the possible actions? If the "Save" button is hidden in a hamburger menu, it’s not visible.
- Consistency: Does the same action always produce the same result?
- The Power of Constraints: Use "forcing functions." If someone needs to do Step A before Step B, make it physically or digitally impossible to click Step B first.
- Design for Error: Assume the user will mess up. Provide a clear "Undo" path. Make it easy to recover.
Actionable Steps for Better Living
You don't have to be a professional designer to apply these lessons.
- Audit Your Space: Look at your home. Is there a drawer you always pull when you should push? Put a small piece of grip tape on the part you're supposed to touch. You’ve just created a signifier.
- Fix Your Mapping: If you have a row of unlabeled cables behind your TV, label them at both ends. This creates a direct mapping between the device and the plug.
- Stop Blaming Yourself: The next time you struggle with a "smart" appliance or a confusing website, stop and analyze the affordances and signifiers. Realizing the fault lies with the design, not your brain, is incredibly liberating.
- Simplify Digital Workflows: If you manage a team or a project, look for "Gulfs of Execution." Are you asking people to jump through five different apps to complete one task? Reduce the friction by aligning the tools with the natural mental model of the job.
The world is full of "Norman Doors," but once you understand the principles of The Design of Everyday Things, you start to see the hidden logic—or lack thereof—in everything around you. Good design is invisible. You only notice it when it’s gone. Focus on making the "how-to" so obvious that the user doesn't even have to think. That is the ultimate goal of human-centered design.