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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.
It is the duty of machines and those who design them to understand people. It is not our duty to understand the arbitrary, meaningless dictates of machines.
Designers need to focus their attention on the cases where things go wrong, not just on when things work as planned.
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 an affordance is jointly determined by the qualities of the object and the abilities of the agent that is interacting. This relational definition of affordance gives considerable difficulty to many people. We are used to thinking that properties are associated with objects. But affordance is not a property. An affordance is a relationship. Whether an affordance exists depends upon the properties of both the object and the agent.
Affordances determine what actions are possible. Signifiers communicate where the action should take place. We need both.
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.
Cognition attempts to make sense of the world: emotion assigns value.
Levels of Processing and the Stages of the Action Cycle. Visceral response is at the lowest level: the control of simple muscles and sensing the state of the world and body. The behavioral level is about expectations, so it is sensitive to the expectations of the action sequence and then the interpretations of the feedback. The reflective level is a part of the goal- and plan-setting activity as well as affected by the comparison of expectations with what has actually happened.
Eliminate the term human error. Instead, talk about communication and interaction: what we call an error is usually bad communication or interaction. When people collaborate with one another, the word error is never used to characterize another person’s utterance. That’s because each person is trying to understand and respond to the other, and when something is not understood or seems inappropriate, it is questioned, clarified, and the collaboration continues. Why can’t the interaction between a person and a machine be thought of as collaboration?
1. What do I want to accomplish? 2. What are the alternative action sequences? 3. What action can I do now? 4. How do I do it? 5. What happened? 6. What does it mean? 7. Is this okay? Have I accomplished my goal?
Everyone knows what feedback is. It helps you know what happened. But how do you know what you can do? That’s the role of feedforward, a term borrowed from control theory. Feedforward is accomplished through appropriate use of signifiers, constraints, and mappings. The conceptual model plays an important role.
The insights from the seven stages of action lead us to seven fundamental principles of design: 1. Discoverability. It is possible to determine what actions are possible and the current state of the device. 2. 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. 3. 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
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One of my self-imposed rules is, “Don’t criticize unless you can do better.”
Whenever knowledge needed to do a task is readily available in the world, the need for us to learn it diminishes. For example, we lack knowledge about common coins, even though we recognize them just fine (Figure 3.1). In knowing what our currency looks like, we don’t need to know all the details, simply sufficient knowledge to distinguish one value of currency from another.
People function through their use of two kinds of knowledge: knowledge of and knowledge how. Knowledge of—what psychologists call declarative knowledge—includes the knowledge of facts and rules.
The most effective way of helping people remember is to make it unnecessary.
The famous “tie a string around your finger” reminder provides only the signal. It gives no hint of what is to be remembered. Writing a note to yourself provides only the message; it doesn’t remind you ever to look at it. The ideal reminder has to have both components: the signal that something is to be remembered, and then the message of what it is.
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 configuration as the objects to be controlled.
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.
It is not possible to eliminate human error if it is thought of as a personal failure rather than as a sign of poor design of procedures or equipment.
The Danish engineer Jens Rasmussen distinguished among three modes of behavior: skill-based, rule-based, and knowledge-based. This three-level classification scheme provides a practical tool that has found wide acceptance in applied areas, such as the design of many industrial systems. Skill-based behavior occurs when workers are extremely expert at their jobs, so they can do the everyday, routine tasks with little or no thought or conscious attention. The most common form of errors in skill-based behavior is slips. Rule-based behavior occurs when the normal routine is no longer applicable but
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The design cures for memory-lapse mistakes are the same as for memory-lapse slips: ensure that all the relevant information is continuously available. The goals, plans, and current evaluation of the system are of particular importance and should be continually available.
But not all errors are easy to detect. Moreover, social pressures often make it difficult for people to admit to their own errors (or to report the errors of others). If people report their own errors, they might be fined or punished. Moreover, their friends may make fun of them. If a person reports that someone else made an error, this may lead to severe personal repercussions. Finally, most institutions do not wish to reveal errors made by their staff.
The Swiss cheese metaphor suggests several ways to reduce accidents: • Add more slices of cheese. • Reduce the number of holes (or make the existing holes smaller). • Alert the human operators when several holes have lined up.
Given the mismatch between human competencies and technological requirements, errors are inevitable. Therefore, the best designs take that fact as given and seek to minimize the opportunities for errors while also mitigating the consequences. Assume that every possible mishap will happen, so protect against them. Make actions reversible; make errors less costly. Here are key design principles: • Put the knowledge required to operate the technology in the world. Don’t require that all the knowledge must be in the head. Allow for efficient operation when people have learned all the
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Engineers and businesspeople are trained to solve problems. Designers are trained to discover the real problems. A brilliant solution to the wrong problem can be worse than no solution at all: solve the correct problem.
Two of the powerful tools of design thinking are human-centered design and the double-diamond diverge-converge model of design. Human-centered design (HCD) is the process of ensuring that people’s needs are met, that the resulting product is understandable and usable, that it accomplishes the desired tasks, and that the experience of use is positive and enjoyable.
HCD is a procedure for addressing these requirements, but with an emphasis on two things: solving the right problem, and doing so in a way that meets human needs and capabilities.
The Double-Diamond Model of Design. Start with an idea, and through the initial design research, expand the thinking to explore the fundamental issues. Only then is it time to converge upon the real, underlying problem. Similarly, use design research tools to explore a wide variety of solutions before converging upon one.
Be-goals are at the highest, most abstract level and govern a person’s being: they determine why people act, are fundamental and long lasting, and determine one’s self-image. Of far more practical concern for everyday activity is the next level down, the do-goal, which is more akin to the goal I discuss in the seven stages of activity. Do-goals determine the plans and actions to be performed for an activity. The lowest level of this hierarchy is the motor-goal, which specifies just how the actions are performed: this is more at the level of tasks and operations rather than activities.
Most companies compare features with their competition to determine where they are weak, so they can strengthen those areas. Wrong, argues Moon. A better strategy is to concentrate on areas where they are stronger and to strengthen them even more. Then focus all marketing and advertisements to point out the strong points. This causes the product to stand out from the mindless herd. As for the weaknesses, ignore the irrelevant ones, says Moon. The lesson is simple: don’t follow blindly; focus on strengths, not weaknesses. If the product has real strengths, it can afford to just be “good enough”
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A rule of thumb is twenty years from first demonstrations in research laboratories to commercial product, and then a decade or two from first commercial release to widespread adoption.
