In our daily interactions with objects, we often encounter moments of frustration that stem from poor design. Consider a door: you approach it, push, but it doesn’t budge. Then you pull, only to find that you should have pushed. This common situation highlights the importance of signifiers and discoverability in design.

Discoverability refers to an object’s ability to communicate what actions are possible, which the author calls affordances. A well-designed object should intuitively inform the user of its functionality. For example, just by looking at a chair we should be able to perceive it’s primary affordance—that we can sit on it and where to sit.

Signifiers are the visual or physical indicators that guide users on how to use an object.

For example, a vertical plate on a door signifies that it should be pushed, while a vertical handle indicates pulling. When designers neglect these intuitive cues called signifiers for the sake of aesthetics, users are left guessing, often leading to the need for explicit instructions like “push” or “pull.” A simple object like a door that must rely on written instructions is a clear example of poor design.

A bad example of signifiers in app design can be found in some poorly designed mobile banking apps. For instance, if the action to transfer funds is hidden deep in a submenu, users may never find it. An effective signifiers might look like a button with an icon of a dollar sign paired with an arrow indicating movement, that would make the action intuitive and prevent confusion.

The paradox of technology is that while it promises to make our lives easier, it can often lead to greater frustration if not well-designed. Consider the evolution of wristwatches. Older models had a single knob for winding and setting the time, a simple and effective design. Modern watches, however, come with many buttons and functions, which can be overwhelming and confusing due to their small size and complex functionality.

Human-Centered Design (HCD) addresses these issues by focusing on the needs and behaviors of users. It starts with observation, understanding how people truly interact with products. Then moves to communication, designing products that accommodate people’s behaviors and expectations. This process involves rapid iteration and testing to refine the design continually.

Ultimately, good design is an act of communication. It requires a deep understanding of the user and the context in which the product will be used. By focusing on discoverability and signifiers, designers can create products that are intuitive and easy to use, minimizing frustration and enhancing the overall user experience.

🔔 3. Clear Feedback: Create smooth and predictable user experiences with clear feedback

Feedback confirms a user’s actions and provides necessary information about the results, reducing confusion and frustration. While lack of feedback can be problematic, excessive or unclear feedback can be equally disruptive.

Imagine pressing an elevator button and nothing happens. You press it repeatedly, unsure if the elevator is responding. This lack of feedback creates confusion and frustration, leaving you uncertain about whether your action was registered.

Now, consider an elevator panel where the button lights up immediately when pressed. This clear, immediate feedback reassures you that the elevator is on its way, eliminating any guesswork.

Good feedback confirms your actions and informs you of the system’s status, making the interaction smooth and predictable.

A simple rule of thumb is to provide feedback in 0.1 seconds after a user action. For example, software app developers can provide a rotating icon or a progress bar to show activity is happening in the background when some process takes longer to complete. This prevents the user from pressing the button repeatedly or feeling confusion about whether their click was registered.

However, feedback can become problematic when it is excessive or unclear. For example, some devices use a series of beeps and flashing lights to indicate various statuses. If these signals are ambiguous or too numerous, they can overwhelm and confuse the user instead of providing clarity. The goal is to strike a balance: enough feedback to inform without causing distraction or misunderstanding.

Continuous feedback is particularly important in many contexts. In cars, for instance, various sounds and lights provide essential information about the vehicle’s status. A car door that hasn’t been shut completely or a muffler that is malfunctioning make distinct sounds that inform us something has not gone right. For electric cars, which are silent at low speeds, designers actually have had to introduce artificial sounds to ensure pedestrian safety, demonstrating how feedback is crucial for safety.

🗺️ 4. Control Mapping: Making controls more usable through intuitive spatial relationships

Natural mapping is about designing controls so that their relationship to the part of the object they control is clear and intuitive. This reduces the cognitive load on users and minimizes errors. Effective natural mapping uses spatial relationships, such as designing a stovetop where the controls are positioned to match the layout of the burners they control.

Natural mapping is a fundamental principle in design that makes the relationship between controls and their effects clear and intuitive. When designers use natural mapping effectively, users can understand how to operate a device or system at a glance, without needing extensive instructions or trial and error.

Imagine walking into a room to give a presentation. You are faced with a long row of identical light switches. You fumble around, trying multiple switches before finding the right ones to control the lights you need. This situation highlights the confusion that arises from poor mapping. Each switch in a row has no discernible relationship to the lights in the room, forcing you to rely on trial and error.

Now, consider a well-designed alternative: a control panel where the switches are arranged in the same layout as the lights they control. If the lights are laid out in a rectangular pattern on the ceiling, the switches are similarly arranged on the panel. This spatial relationship allows you to intuitively understand which switch controls which light, reducing the need for guesswork. Don Norman actually installed a light switch panel just like this in his home.

The principle of natural mapping extends beyond light switches. For example, consider the controls on a stovetop. Ideally, the knobs should be arranged in a way that mirrors the layout of the burners. If the burners are in a rectangular formation, the knobs should be too. This way, you immediately know which knob controls which burner, without having to look at labels or instructions.

Good mapping also follows the principle of grouping related functions together and maintaining proximity between controls and the objects they manipulate. For instance, in a car, the window controls are placed on the door next to the window. This proximity makes it clear and convenient to understand their function.

🚧 5. Guiding Constraints: Design limitations that naturally lead users to the correct actions

Constraints are essential in design as they limit and guide user actions, making it easier to determine the proper course of action. There are four types of constraints: physical, cultural, semantic, and logical, each providing different ways to influence user behavior and ensure products feel intuitive.

Constraints are a crucial aspect of design that helps guide users towards the correct actions while limiting the possibility of errors. By incorporating thoughtful constraints, designers can create products that are intuitive and easy to use, even when someone has never used it before.

There are four main types of constraints:

1. Physical Constraints: These rely on the physical properties of objects, like a square peg won’t fit into a round hole. A practical example is the design of camera batteries, which can only be inserted in one way, unlike the common AA battery designs that can fit backwards.
2. Cultural Constraints: These are based on learned conventions and social norms. How machines are used can be standardized by cultural conventions or laws, and that helps us to use a new machine quickly. For example, you can probably sit in most cars and drive them right away.
3. Semantic Constraints: These involve the meaning we derive from context. Semantic constraints leverage our understanding of the world to inform us how to interact with objects. For example, there is only one meaningful way to sit on a motorcycle, guided by its shape and structure.
4. Logical Constraints: These use logical relationships and reasoning to guide user actions effectively. An example is the natural mapping where the left switch controls the left light in a room, and the right switch controls the right light.

In addition to these constraints, designers can use mechanisms like interlocks, lock-ins, and lockouts to enforce desired behaviors. For example, a car key must be inserted before the vehicle can start (interlock), a computer program may prompt you to save before closing (lock-in), and child locks on cabinets prevent access to dangerous items (lockout).

Sometimes, if all else fails, standardization becomes necessary. For example, standardized designs for faucets ensure they all work in the same way, reducing confusion. However, sticking to old standards can sometimes hinder progress, as seen with the slow global adoption of the metric system.

🧠 6. Conceptual Models: Create simplified mental models to give users a sense of control

Conceptual models are simplified explanations of how things work, helping users form mental models to understand and interact with products. Effective conceptual models provide a sense of control and aid in troubleshooting when things go wrong.

Conceptual models play a crucial role in how we interact with and understand everyday objects and systems. These models provide simplified explanations that help us form mental images of how things work. For example, when using a computer, the analogy of files and folders allows us to easily grasp how data is organized and accessed, even if we don’t understand the underlying technology.

A good conceptual model gives users a feeling of control, enabling them to predict outcomes and troubleshoot problems.

On the other hand, poor conceptual models can lead to confusion and frustration. Consider the case of a thermostat: many people believe that turning it all the way up will heat a room faster, a misconception based on a flawed conceptual model. The reality is that thermostats work to maintain a set temperature, not to control the speed of heating.

People are natural storytellers, constantly seeking to explain and make sense of their experiences. They piece together information from their interactions with a product, forming explanations and stories that guide their use. Even if these stories are based on incorrect assumptions, they persist as long as they seem to match the observed outcomes.

The concept of the System Image is critical here. The designer’s conceptual model shapes the system image, which in turn influences the user’s conceptual model. However, there is often a disconnect between the designer’s intentions and the user’s understanding. This gap can result in users forming incorrect theories about how a product works based on incomplete or misleading information.

Effective design should aim to create clear and accurate conceptual models that align the system image with the user’s mental model. By doing so, designers can help users feel more in control, reduce errors, and enhance overall satisfaction with the product.

❌ 7. Designing for Errors: Minimize the impact of mistakes by accounting for human limitations

Errors often blamed on human mistakes are frequently due to poor design. Designers need to create systems that account for human limitations and predict common errors, reducing their impact with techniques like an undo button, constraints, checklists, and sensibility checks.

In many instances, what is labelled “human error” is actually a result of poor design. When systems fail to consider human limitations and behaviors, users are more likely to make mistakes. This often leads to frustration and self-blame, when the true fault lies in the design of the system.

Consider a scenario where software requires users to press “enter” to save their work, but pressing “return” erases everything. This is an actual case study from a company the author consulted for. Many company employees tested the software and accidentally erased their work, but didn’t report the error because they blamed themselves for “not using it right” so the designer was unaware of the huge flaw. A better design would recognize the potential for such mistakes and incorporate safeguards, like using a different key for erasing data or providing a confirmation prompt beforehand.

Root cause analysis is a powerful tool in addressing these issues. By continually asking “why” until the fundamental cause of a problem is identified, designers can understand and address the underlying issues that lead to errors. This method, pioneered by Toyota, has been instrumental in improving product quality and reliability. When a defect is spotted in a Toyota factory, any employee can pull a special andon cord, which stops production until the cause of the defect is identified, thus preventing future occurrences.

Errors are often exacerbated by social and institutional pressures, such as tight deadlines or unrealistic expectations. In many situations, an employee cannot get their job done unless they cut corners, not following every safety procedure. In high-stakes environments, like aviation, this can have catastrophic consequences. For instance, in the 1977 Tenerife airport disaster, time pressure and poor communication led to a fatal misjudgment, causing the deadliest aircraft collision of all time. Good systems design allows for clear, stress-free decision-making.

To reduce errors, systems should incorporate multiple strategies:

• Constraints can prevent mistakes by making incorrect actions difficult or impossible. For example, ATMs require you to take your card before dispensing cash to prevent leaving the card behind.
• Checklists are another effective tool, used in aviation and healthcare to ensure that all critical steps are followed.
• Minimizing interruptions can also reduce errors. The “sterile cockpit” rule in aviation prohibits non-essential conversation during critical phases of flight to maintain focus.
• UNDO options in software allows users to easily correct mistakes, reducing the consequences of slips.
• Sensibility checks in technology can prevent illogical actions. For instance, financial apps often ask for confirmation before sending an unusually large sum of money, ensuring that the user intended the action.

By designing with these principles in mind, we can create systems that not only accommodate human limitations but also enhance overall safety and usability. This approach shifts the responsibility from the user to the design, fostering environments where errors are less likely and more easily corrected.

🔄 8. Iterative User Testing: Continuously refine your product with multiple rounds of testing and feedback

The most crucial aspect of design is solving the correct problem by identifying the root cause through continuous questioning. The Human-Centered Design Process involves: observation, idea generation, prototyping, and testing. Followed by refinement with multiple iterations to ensure the product meets user needs and provides a positive experience.

In design, one of the fundamental principles is to ensure that you are solving the right problem. This often involves delving deep into the issues and repeatedly asking “why” until the true root cause is identified. For instance, if users are requesting a more powerful drill, the real need might be to hang shelves more effectively, which could lead to exploring entirely new solutions beyond just a better drill.

The Human-Centered Design (HCD) process is essential for developing products that are not only functional but also intuitive and enjoyable to use.

1. This process starts with observation, where designers engage with potential users to understand their behaviors, needs, and pain points. Unlike market research, which often focuses on broad quantitative data, design research is more qualitative, involving direct interaction with a smaller group of users to uncover deeper insights.
2. Next comes idea generation, a creative phase where all ideas are welcome, and nothing is dismissed too quickly. Encouraging wild ideas can lead to innovative solutions, as these often challenge the status quo and uncover new possibilities. For example, questioning why a task has always been done a certain way can reveal hidden assumptions and lead to breakthroughs.
3. Prototyping involves creating simple models of the product, which can range from sketches to cardboard models or digital mock-ups. The “Wizard of Oz” technique, where a prototype is manually operated behind the scenes to simulate functionality, can be particularly useful for testing concepts without full development.
4. Testing these prototypes with a small group of users—typically around five at a time—provides invaluable feedback. Observing users interact with the prototype reveals usability issues and insights that might not have been anticipated.

Iteration is the final and ongoing phase, emphasizing the HCD process is a cycle that you repeat. Each round of testing informs further refinements, making the product better and better. This iterative approach, common in software development methodologies like Scrum and Agile, contrasts with the older, linear waterfall method, which can be inflexible and less suited to innovative product development.

For example, consider developing a new app for managing personal finances. The process would start with observing how people currently handle their finances, understanding their frustrations and needs. Idea generation might produce a range of concepts, from simple budgeting tools to comprehensive financial planners. Prototyping a few of these ideas and testing them with users will highlight which features are most useful and which interfaces are most intuitive. Based on this feedback, the design is iterated and refined, ensuring the final product truly meets user needs and offers a seamless experience.

By continuously testing and refining, designers can ensure that the final product is not only effective in solving the right problem but also provides a positive and engaging user experience.

⚖️ 9. Balancing Innovation & Competition: Navigate the pressures of competition, technology, and customer needs for successful design

Effective product design requires balancing competing priorities such as affordability, beauty, utility, and differentiation from competition—all coming from various departments of the company. While innovation can be both incremental and radical, it often faces constraints like budget and schedule.

Designing a successful product is a complex challenge that involves balancing various competing priorities and departments including design, marketing, engineering, accounting, etc. For example, some team members may prioritize affordability, ensuring that the product is accessible to a wide range of consumers. Others might focus on aesthetics, aiming to create a beautiful and appealing product. Utility is another crucial factor, as the product must serve its intended function effectively. Lastly, differentiation ensures the product stands out in a crowded market.

In reality, product development is often heavily influenced by what competitors are doing and the emergence of new technologies. This competitive landscape can lead to a phenomenon known as “featuritis,” where products become overloaded with features in an attempt to outdo competitors and satisfy all customer requests. However, this can detract from the product’s core functionality and user experience.

The moral obligations of design also come into play. Redesigning products solely to drive sales—by making them less durable, creating seasonal fashions, or adding unnecessary features—raises important ethical questions.

Competitive forces play a significant role in shaping product design. Factors like price, features, and quality are paramount. New products must satisfy multiple stakeholders, including investors, distributors, and end-users.

There are two forms of innovation: incremental and radical. Incremental innovation involves continuous testing and refinement of existing products, providing a reliable path to success. Radical innovation, on the other hand, is often driven by new technologies and can lead to groundbreaking products, but it carries a much higher risk of failure.

For instance, the development of multitouch displays began in the 1980s, but it took over 20 years for the technology to gain traction and become mainstream. This long timeline highlights the challenges of bringing new technologies to market and the importance of patience and persistence in the innovation process.

As we look to the future, technology will continue to change how we live and work. The author has a thought-provoking idea that we humans are not smart by our sheer brainpower, but it is “things that make us smart” emphasizes the synergy between humans and machines. Rather than viewing technology as a competitor, we should see it as a collaborator that enhances our capabilities. For example, the best chess players in the world work WITH a computer, by doing so they can beat all other players or all other computers working separately.

The rise of individual creators using new tools to bring their ideas to life is another exciting development. Self-publishing, 3D printing, and other technologies empower individuals to innovate and share their creations with the world, democratizing the design process.

1. Add clear signifiers: For every important affordance or capability your product allows, make sure there is some visible clue that reveals that utility. For example, a handle on top if it’s meant to be picked up often.
2. Ensure immediate feedback: Add audible alerts or visual indicators that provide instant confirmation of important actions.
3. Include constraints: Use templates or checklists for an important process to guide correct actions and reduce errors.
4. Create mental models: Practice explaining tasks using a physical analogy or simplified diagrams.
5. Reduce errors: Add safeguards to minimize the impact of mistakes like confirmation prompts, auto-save, or undo buttons in software apps.
6. Test regularly with users: Gather real-world feedback from users to improve your product or project.
7. Stay updated on trends: Follow industry trends and competitor product to inform your future innovations.