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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.
To understand products, it is not enough to understand design or technology: it is critical to understand business.
The one thing I can predict with certainty is that the principles of human psychology will remain the same, which means that the design principles here, based on psychology, on the nature of human cognition, emotion, action, and interaction with the world, will remain unchanged.
Affordances define what actions are possible. Signifiers specify how people discover those possibilities: signifiers are signs,
The day the product team is announced, it is behind schedule and over its budget.
My problems with doors have become so well known that confusing doors are often called “Norman doors.” Imagine becoming famous for doors that don’t work right.
Two of the most important characteristics of good design are discoverability and understanding. Discoverability: Is it possible to even figure out what actions are possible and where and how to perform them? Understanding: What does it all mean? How is the product supposed to be used? What do all the different controls and settings mean?
With complex devices, discoverability and understanding require the aid of manuals or personal instruction. We accept this if the device is indeed complex, but it should be unnecessary for simple things.
This book covers everyday things, focusing on the interplay between technology and people to ensure that the products actually fulfill human needs while being understandable and usable. In the best of cases, the products should also be delightful and enjoyable, which means that not only must the requirements of engineering, manufacturing, and ergonomics be satisfied, but attention must be paid to the entire experience,
Interaction design: The focus is upon how people interact with technology. The goal is to enhance people’s understanding of what can be done, what is happening, and what has just occurred. Interaction design draws upon principles of psychology, design, art, and emotion to ensure a positive, enjoyable experience.
Design is concerned with how things work, how they are controlled, and the nature of the interaction between people and technology.
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.
The problem with the designs of most engineers is that they are too logical. We have to accept human behavior the way it is, not the way we would wish it to be.
Today, I realize that design presents a fascinating interplay of technology and psychology, that the designers must understand both.
So we must design our machines on the assumption that people will make errors.
everyday life sometimes seems like a never-ending fight against confusion, continued errors, frustration, and a continual cycle of updating and maintaining our belongings.
But even though much has improved, the rapid rate of technology change outpaces the advances in design.
The solution is human-centered design (HCD), an approach that puts human needs, capabilities, and behavior first, then designs to accommodate those needs, capabilities, and ways of behaving.
Designers need to focus their attention on the cases where things go wrong, not just on when things work as planned.
The philosophy and procedures of HCD add deep consideration and study of human needs to the design process, whatever the product or service, whatever the major focus.
Great designers produce pleasurable experiences.
Experience is critical, for it determines how fondly people remember their interactions.
Discoverability results from appropriate application of five fundamental psychological concepts covered in the next few chapters: affordances, signifiers, constraints, mappings, and feedback. But there is a sixth principle, perhaps most important of all: the conceptual model of the system. It is the conceptual model that provides true understanding.
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.
If an affordance or anti-affordance cannot be perceived, some means of signaling its presence is required: I call this property a signifier (discussed in the next section).
Perceived affordances help people figure out what actions are possible without the need for labels or instructions. I call the signaling component of affordances signifiers.
Affordances determine what actions are possible. Signifiers communicate where the action should take place. We need both.
Good design requires, among other things, good communication of the purpose, structure, and operation of the device to the people who use it. That is the role of the signifier.
For me, the term signifier refers to any mark or sound, any perceivable indicator that communicates appropriate behavior to a person.
Whatever their nature, planned or accidental, signifiers provide valuable clues as to the nature of the world and of social activities. For us to function in this social, technological world, we need to develop internal models of what things mean, of how they operate.
In design, signifiers are more important than affordances, for they communicate how to use the design. A signifier can be words, a graphical illustration, or just a device whose perceived affordances are unambiguous. Creative designers incorporate the signifying part of the design into a cohesive experience.
Mapping is a technical term, borrowed from mathematics, meaning 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.
The relationship between a control and its results is easiest to learn wherever there is an understandable mapping between the controls, the actions, and the intended result.
Some natural mappings are cultural or biological, as in the universal standard that moving the hand up signifies more, moving it down signifies less, which is why it is appropriate to use vertical position to represent intensity or amount.
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.
Note that there are many mappings that feel “natural” but in fact are specific to a particular culture: what is natural for one culture is not necessarily natural for another.
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 also be informative.
Poor feedback can be worse than no feedback at all, because it is distracting, uninformative, and in many cases irritating and anxiety-provoking.
Too much feedback can be even more annoying than too little.
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 is essential, but not when it gets in the way of other things, including a calm and relaxing environment.
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.
A conceptual model is an explanation, usually highly simplified, of how something works. It doesn’t have to be complete or even accurate as long as it is useful. The files, folders, and icons you see displayed on a computer screen help people create the conceptual model of documents and folders inside the computer,
Mental models, as the name implies, are 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.
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.
How do we form an appropriate conceptual model for the devices we interact with? We cannot talk to the designer, so we rely upon whatever information is available to us: what the device looks like, what we know from using similar things in the past, what was told to us in the sales literature, by salespeople and advertisements, by articles we may have read, by the product website and instruction manuals. I call the combined information available to us the system image.
The system image is what can be perceived from the physical structure that has been built (including documentation, instructions, signifiers, and any information available from websites and help lines). The user’s conceptual model comes from the system image, through interaction with the product, reading, searching for online information, and from whatever manuals are provided.
