Part 1 — The Design of Everyday Things (Revised & Expanded Edition)—Book Summary & Key Points
The Design of Everyday Things is a book about how design serves as the communication between object and user, and how to optimise that conduit of communication in order to make the experience of using the object pleasurable.
“Good design is actually a lot harder to notice than poor design, in part because good designs fit our needs so well that the design is invisible, serving us without drawing attention to itself. Bad design, on the other hand, screams out its inadequacies, making itself very noticeable.”
— Don Norman
Chapter 1 — The Psychopathology of Everyday Things
Is it possible to even figure out what actions are possible and where and how to perform them?
What does it all mean? How is the product supposed to be used? What do all the different controls and settings mean? Many products defy understanding simply because they have too many functions and controls.
Design is concerned with how things work, how they are controlled, and the nature of the interaction between people and technology. When done well, the results are brilliant, pleasurable products. When done badly, the products are unusable, leading to great frustration and irritation. Or they might be usable, but force us to behave the way the product wishes rather than as we wish.
Good design requires good communication, especially from machine to person, indicating what actions are possible, what is happening, and what is about to happen.
Communication is especially important when things go wrong. Designers need to focus their attention on the cases where things go wrong, not just on when things work as planned.
Fundamental Principles of Interaction
Great designers produce pleasurable experiences. Experience is critical, for it determines how fondly people remember their interactions.
Cognition and emotion are tightly intertwined, which means that the designers must design with both in mind.
When we interact with a product, we need to figure out how to work it. Discoverability results from appropriate application of six fundamental psychological concepts: affordances, signifiers, constraints, mappings, feedback, conceptual model.
An affordance is a relationship between the properties of an object and the capabilities of the agent that determine just how the object could possibly be used.
The presence of affordance is jointly determined by the qualities of the object and the abilities of the agent that is interacting. An affordance is a relationship. Whether an affordance exists depends upon the properties of both the object and the agent.
To be effective, affordances and anti-affordances have to be discoverable — perceivable.
Affordances exist even if they are not visible. For designers, their visibility is critical: visible affordances provide strong clues to the operations of things.
Perceived affordances help people figure out what actions are possible without the need for labels or instructions. If an affordance or anti-affordance cannot be perceived, some means of signaling its presence is required.
Affordances determine what actions are possible. Signifiers communicate where the action should take place.
People need some way of understanding the product or service they to use, some sign of what it is for, what is happening, and what the alternative actions are. Designers need to provide these clues.
The term signifiers refers to any mark of sounds, any perceivable indicator that communicates appropriate behaviour to a person.
Signifiers are signals. Some signifiers are signs, labels, and drawings placed in the world. Some signifiers are simply the perceived affordances, such as the handle of a door or the physical structure of a switch.
Note that some perceived affordances may not be real: they may look like doors or places to push, or an impediment to entry, when in fact they are not. These are misleading signifiers, oftentimes accidental but sometimes purposeful, as when trying to keep people from doing actions for which they are not qualified, or in games, where one of the challenges is to figure out what is real and what is not.
- Affordances are the possible interactions between people and the environment. Some affordances are perceivable, others are not.
- Perceived affordances often act as signifiers, but they can be ambiguous.
- Signifiers signal things, in particular what actions are possible and how they should be done. Signifiers must be perceivable, else they fail to function.
The relationship between the elements of two sets of things.
Mapping is an important concept in the design and layout of controls and displays. When the mapping uses spatial correspondence between the layout of the controls and the devices being controlled, it is easy to determine how to use them.
Groupings and proximity are important principles from Gestalt psychology that can be used to map controls to function: related controls should be grouped together. Controls should be close to the item being controlled.
Best mapping: Controls are mounted directly on the item to be controlled.
Second-best mapping: Controls are as close as possible to the object to be controlled.
Third-best mapping: Controls are arranged in the same spatial con- figuration as the objects to be controlled.
Feedback — communicating the results of an action — is a well-known concept from the science of control and information theory.
Feedback must be immediate: even a delay of a tenth of a second can be disconcerting. If the delay is too long, people often give up, going off to do other activities.
Feedback must be informative: It can be wasteful of resources when the system spends considerable time and effort to satisfy the request, only to find that the intended recipient is no longer there.
When the signal is auditory, in many cases we cannot even be certain which device has created the sound. If the signal is a light, we may miss it unless our eyes are on the correct spot at the correct time.
Poor feedback can be worse than no feedback at all, because it is distracting, uninformative, and in many cases irritating an anxiety provoking.
On the other hand, too many announcements cause people to ignore all of them, or wherever possible, disable all of them, which means that critical and important ones are apt to be missed.
Feedback has to be planned. All actions need to be confirmed, but in a manner that is unobtrusive. Feedback must also be prioritized, so that unimportant information is presented in an unobtrusive fashion, but important signals are presented in a way that does capture attention. When there are major emergencies, then even important signals have to be prioritized.
5. Conceptual Models
A conceptual model is an explanation, usually highly simplified, of how something works.
There are often multiple conceptual models of a product or device.
People’s conceptual models for the way that regenerative braking in a hybrid or electrically powered automobile works are quite different for average drivers than for technically sophisticated drivers, different again for whoever must service the system, and yet different again for those who designed the system.
The conceptual models in people’s minds that represent their understanding of how things work.
Different people may hold different mental models of the same item. The models can even be in conflict.
Conceptual models are often inferred from the device itself. Some models are passed on from person to person. Some come from manuals. Usually the device itself offers very little assistance, so the model is constructed by experience.
The major clues to how things work com from their perceived structure — in particular from signifiers, affordances, constraints and mappings.
Conceptual models are valuable in providing understanding, in predicting how things will behave, and in figuring out what to do when things do not go as planned. A good conceptual model allows us to predict the effects of our actions.
The System Image
Combined information available to us.
The designer’s conceptual model is the designer’s conception of the look, feel, and operation of a product.
The system image is what can be derived from the physical structure that has been built (including documentation).
The user’s mental model is developed through interaction with the product and the system image. Designers expect the user’s model to be identical to their own, but because they cannot communicate directly with the user, the burden of communication is with the system image.
Most important is the provision of a good conceptual model that guides the user when thing go wrong. With a good conceptual model, people can figure out what has happened and correct the things that went wrong.
Good conceptual models are the key to understandable, enjoyable products: good communication is the key to good conceptual models.
Chapter 2 — The Psychology of Everyday Actions
When people use something, they face two gulfs:
Gulf of Execution, where they try to figure out how it operates.
Gulf of Evaluation, where they try to figure out what happened.
- amount of effort to interpret the physical state of the device
- determine how well the expectations and intentions have been met.
The role of the designer is to help people bridge the two gulfs. Feedback and good conceptual model help bridge the Gulf of Evaluation.
The 7 Stages of Action
There are 2 parts to an action: executing the action (doing) and evaluating the results (interpreting).
Not all of the activity in the stages is conscious. Goals tend to be, but even they may be subconscious.
It is only when we come across something new or reach some impasse, some problem that disrupts the normal flow of activity, that conscious attention is required.
The action cycle can start from the top, by establishing a new goal, in which case we call it goal-driven behaviour.
The action cycle can also start from the bottom, triggered by some event in the world, in which case we call it either data-driven or event-driven behaviour.
The seven stages provide a guideline for developing new products or services. The gulfs are obvious places to start, for either gulf, whether or execution or evaluation, is an opportunity for product enhancement.
What about radical ideas, ones that introduce new product categories to the marketplace?
These come about by reconsidering the goals, and always asking what the real goal is: what is called the root cause analysis.
Human Thought: Mostly Subconscious
Most of human behaviour is a result of subconscious processes. We are unaware of them.
As a result, many of our beliefs about how people behave — including beliefs about ourselves — are wrong.
Cognitive thoughts lead to emotions: emotions drive cognitive thoughts. The brain is structured to act upon the world, and every action carries with it expectations, and these expectations drive emotions.
The emotional system is a powerful information processing system that works in tandem with cognition. Cognition attempts to make sense of the world: emotion assigns value. Cognition provides understanding: emotion provides value judgements.
A human without a working emotional system has difficulty making choices. A human without a cognitive system is dysfunctional.
Human Cognition and Emotion
The visceral system allows us to respond quickly and subconsciously, without conscious awareness or control.
- Minimises its ability to learn.
- Responds to the immediate present and produces an affective state, relatively unaffected by context or history.
- Tightly coupled to the body’s musculature — the motor system. This is what causes us to fight or flee, or to relax.
For designers, the visceral response is about immediate perception.
This has nothing to do with how usable, effective, or understandable the product is. It is all about attraction and repulsion. Great designers use their aesthetic sensibilities to drive these visceral responses.
The Behavioural Level
The behavioural level is the home of learned skills, triggered by situations that match the appropriate patterns.
- Actions and analyses at this level are largely subconscious.
- Even though we are aware of our actions, we are often unaware of the details. Our responses occur far too quickly for conscious control: it is the behavioural level that takes control.
- When we perform a well-learned action, all we have to do is think of the goal and the behavioural level handles all the details: the conscious mind has little or no awareness beyond creating the desire to act.
For designers, the most critical aspect of the behavioural level is that every action is associated with an expectation.
The information in the feedback loop of evaluation confirms or disconfirms the expectations, resulting in satisfaction or relief, disappointment or frustration.
Feedback is critical to managing expectations, and good design provides this. Feedback — knowledge of results — is how expectations are resolved and is critical to learning and the development of skilled behaviour.
The Reflective Level
The reflective level is the home of conscious cognition.
This is where deep understanding develops, where reasoning and conscious decision-making take place. The visceral and behavioural levels are subconscious and, as a result, they respond rapidly, but without much analysis. Reflection is cognitive, deep, and slow. It often occurs after the events have happened.
Design must take place at all levels: Visceral, Behavioural and Reflective
To the designer, reflection is perhaps the most important of the levels of processing. Reflection is conscious, and the emotions produced at this level are the most protracted: those that assign agency and cause, such as guilt and blame or praise and pride.
Memories last far longer than the immediate experience or the period of usage (domains of the visceral and behavioural levels).
It is reflection that drives us to recommend a product, to recommend that others use it — or perhaps to avoid it.
Understanding arises at a combination of the behavioural and reflective levels. Enjoyment requires all three.
High-level reflective cognition can trigger lower-level emotions. Lower-level emotions can trigger higher level reflective cognition.
The flow state occurs when the challenge of the activity just slightly exceeds our skill level, so full attention is continually required. Flow requires that the activity be neither too easy nor too difficult relative to our level of skill. The constant tension coupled with continual progress and success can be an engaging, immersive experience sometimes lasting for hours.
Blaming the Wrong Things
People tend to assign a causal relation whenever two things occur in succession.
- If something unexpected event happens in my home just after I have taken some action, I am apt to conclude that it was caused by that action, even if there really was no relationship between the two.
- If I do something expecting a result and nothing happens, I am apt to interpret the lack of feedback as an indication that I didn’t do the action correctly.
Often people will use their own conceptual models of the world to determine the perceived causal relationship between the things being blamed and the result. The causal relationship does not have to exist; the person simply has to think it is there. Sometimes the result is to attribute cause to things that has nothing to do with the action.
Suppose I try to use an everyday thing, but I can’t. Who is at fault: me or the thing? We are apt to blame ourselves, especially if others are able to use it.
Refers to the situation in which people experience repeated failure at a task. As a result, they decide that the task cannot be done, they stop trying.
When people have trouble using technology, they tend to blame themselves. Worse, the more they have trouble, the more helpless they may feel, believing that they must be technically inept.
We need to remove the word failure from our vocabulary, replacing it instead with learning experience. To fail is to learn: we learn more from our failures than from our successes.
- Do not blame people when they fail to use your products properly.
- Take people’s difficulties as signifiers of where the product can be improved.
- Eliminate all error messages from electronic or computer systems. Instead, provide help and guidance.
- Make it possible to correct problems directly from help and guidance messages. Allow people to continue with their task: Don’t impede progress — help make it smooth and continuous. Never make people start over.
- Assume that what people have done is partially correct, so if it is inappropriate, provide the guidance that allows them to correct the problem and be on their way.
- Think positively, for yourself and for the people you interact with.
The Seven Stages of Action: Seven Fundamental Design Principles
The seven stages model of the action cycle can be a valuable design tool, for it provides a basic checklist of questions to ask.
Feedforward is accomplished through appropriate use of signifiers, constraints, and mappings. The conceptual model plays an important role. Feedback is accomplished through explicit information about the impact of the action.
Both feedback and feedforward need to be presented in a form that is readily interpreted by the people using the system. The presentation has to match how people view the goal they are trying to achieve and their expectations. Information must match human needs.
The insights from 7 stages of action lead us to 7 fundamental of design.
- Discoverability. It is possible to determine what actions are possible and the current state of the device.
- Feedback. There is full and continuous information about the results of actions and the current state of the product or service. After an action has been executed, it is easy to determine the new state.
- Conceptual model. The design projects all the information needed to create a good conceptual model of the system, leading to understanding and a feeling of control. The conceptual model enhances both discoverability and evaluation of results.
- Affordances. The proper affordances exist to make the desired actions possible.
- Signifiers. Effective use of signifiers ensures discoverability and that the feedback is well communicated and intelligible.
- Mappings. The relationship between controls and their actions follows the principles of good mapping, enhanced as much as possible through spatial layout and temporal contiguity.
- Constraints. Providing physical, logical, semantic, and cultural constraints guides actions and eases interpretation.
Chapter 3 — Knowledge in the Head and in the World
Not all knowledge required for precise behavior has to be in the head. It can be distributed — partly in the head, partly in the world, and partly in the constraints of the world.
Precise behavior can emerge from imprecise knowledge for four reasons:
- Knowledge is both in the head and in the world. Behaviour is determined by combining the knowledge in the head with that in the world.
- Great precision is not required. Perfect behaviour results if the combined knowledge in the head and in the world is sufficient to distinguish an appropriate choice from all others.
- Natural constraints exist in the world. Each object has physical features that limits its relationship with other objects, the operations that can be performed on it, and so on.
- Knowledge of cultural constraints and convention exists in the head.
Because behavior can be guided by the combination of internal and external knowledge and constraints, people can minimize the amount of material they must learn, as well as the completeness, precision, accuracy, or depth of the learning.
Knowledge is in the world
- Knowledge of (Declarative Knowledge) — Knowledge of facts and rules. (Stop at red traffic lights. etc)
- Knowledge how (Procedural knowledge) — Knowledge that enables a person to be a skilled musician, to return a serve in tennis etc.
- Difficult to teach, best taught by demonstration and best learned through practice.
- Largely subconscious, residing at the behavioural level of processing.
Knowledge in the world is usually easy to come by. Signifiers, physical constraints, and natural mappings are all perceivable cues that act as knowledge in the world.
The Structure of Memory
Memory is knowledge in the head.
Short term memory (STM)
- Retains the most recent experiences that is current being thought about.
- Information is retained automatically and retrieved without effort.
- Amount of information can be retained is limited.
- Retention is affected by both time and the number of items.
- Computer systems often enhance people’s frustration when things go wrong by presenting critical information in a message that then disappears from the display.
- To maximise efficiency of working memory it is best to present different information over different modalities: sight, sound, touch (haptics), hearing, spatial, location and gestures.
Long term memory (LTM)
- Memory for the past.
- It takes time for information to get in LTM and time and effort to get it out again.
- We do not remember our experiences as an exact recording; rather, as bits and pieces that are reconstructed and interpreted each time we recover the memories, which means they are subject to all the distortions and changes that the human explanatory mechanism, imposes upon life.
- Reconstruction of the knowledge — subject to biases and distortion.
How people retrieve knowledge:
- Memory of arbitrary things. — The items to be retained seem arbitrary, with no meaning and no particular relationship to one another or to things already known.
- Memory for meaningful things. The items to be retained form meaningful relationships with themselves or with other things already known. Part of the power of a good conceptual model lies in its ability to provide meaning to things.
Provide meaningful structures. Perhaps a better way is to make memory unnecessary: put the required information in the world.
Approximate Models: Memory in the Real World
Conscious thinking takes time and mental resources. Well-learned skills bypass the need for conscious oversight and control: conscious control is only required for initial learning and for dealing with unexpected situations. Continual practice automates the action cycle, minimising the amount of conscious thinking and problem-solving required to act.
When precision is required, use a calculator. That’s what machines are good for: providing great precision. For most purposes, estimates are good enough. Machines should focus on solving arithmetic problems.
People should focus on higher level issues, such as the reason the answer was needed.
Knowledge in the world, external knowledge, is a valuable tool for remembering, but only if it is available at the right place, at the right time, in the appropriate situation. Otherwise, we must use knowledge in the head, in the mind.
Effective memory uses all the clues available: knowledge in the world and in the head, combining world and mind.
Reminder: Prospective Memory (Memory for the future)
Prospective Memory — The task of remembering to do some activity at a future time.
Memory for the future — Planning abilities, the ability to images future scenarios.
2 different aspects to a reminder:
- The Signal — Knowing that something is to be remembered.
- The Message — Remembering the information itself.
The Tradeoff Between Knowledge in the World and in the Head
Knowledge in the world and knowledge in the head are both es- sential in our daily functioning. But to some extent we can choose to lean more heavily on one or the other. That choice requires a tradeoff — gaining the advantages of knowledge in the world means losing the advantages of knowledge in the head.
Combination of technology and people that creates super-powerful beings. Technology does not make us smarter. People do not make technology smarter. It is the combination of the two, the person plus the artefact, that is smart. Together, with out tools, we are a powerful combination. On the other hand, if we are suddenly without these external devices, then we don’t do very well.
Chapter 4 — Knowing what to do: Constraints, Discoverability and Feedback
Knowledge in the world includes perceived affordances and signifiers, the mappings between the parts that appear to be controls or places to manipulate and the resulting actions, and the physical constraints that limit what can be done. Knowledge in the head includes conceptual models; cultural, semantic, and logical constraints on behavior; and analogies between the current situation and previous experiences with other situations.
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.
- Physical limitations constrain possible operations.
- Physical constraints are made more effective and useful if they are easy to see and interpret, for then the set of actions is restricted be- fore anything has been done.
- Cultural issues are at the root of many of the problems we have with new machines: there are as yet no universally accepted conventions or customs for dealing with them.
- Likely to change with time.
- Semantics is the study of meaning. Semantic constraints are those that rely upon the meaning of the situation to control the set of possible actions.
- New technologies change the meanings of things. And creative people continually change how we interact with our technologies and one another.
- When cars become fully automated, communicating among themselves with wireless networks, what will be the meaning of the red lights on the rear of the auto?
- The meanings of today may not be the meanings of the future.
- There are no physical or cultural principles here; rather, there is a logical relationship between the spatial or functional layout of components and the things that they affect or are affected by.
Constraints that Force the Desired Behaviour
- A form of physical constraint: situations in which the actions are constrained so that failure at one stage prevents the next from happening.
- Forcing functions are the extreme case of strong constraints that can prevent inappropriate behavior.
- Forces operations to take place in proper sequence.
- Keeps an operation active, preventing someone from prematurely stopping it.
Whereas a lock-in keeps someone in a space or prevents an action until the desired operations have been done, a lockout prevents someone from entering a space that is dangerous, or prevents an event from occurring.
Forcing functions can be a nuisance in normal usage. The result is that many people will deliberately disable the forcing function, thereby negating its safety feature. The clever designer has to minimize the nuisance value while retaining the safety feature of the forcing function that guards against the occasional tragedy.
Conventions, Constraints, and Affordances
Conventions are a special kind of cultural constraint. Although conventions provide valuable guidance for novel situations, their existence can make it difficult to enact change.
Consistency in design is virtuous. It means that lessons learned with one system transfer readily to others. On the whole, consistency is to be followed.
If a new way of doing things is only slightly better than the old, it is better to be consistent. But if there is to be a change, everybody has to change. Mixed systems are confusing to everyone.
When a new way of doing things is vastly superior to another, then the merits of change outweigh the difficulty of change. Just because something is different does not mean it is bad. If we only kept to the old, we could never improve.
Standardisation 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.
If you can’t put the knowledge on the device (that is, knowledge in the world), then develop a cultural constraint: standardise what has to be kept in the head. The standards should reflect the psychological conceptual models, not the physical mechanics.
Using Sounds as Signifier
Sometimes everything that is needed cannot be made visible. Enter sound: sound can provide information available in no other way. Sound can tell us that things are working properly or that they need maintenance or repair.
Sounds should be generated so as to give knowledge about the source. They should convey something about the actions that are taking place, actions that matter to the user but that would otherwise not be visible.
Skeuomorphic is the technical term for incorporating old, familiar ideas into new technologies, even though they no longer play a functional role. It gives comfort and makes learning easier. Existing conceptual models ned only be modified rather than replace. Eventually, new forms emerge that have no relationship to the old, but the skeuomorphic designs probably helped the transition.
Summary(Part 2) will be published soon.