Affordances are the relationships (read: possible actions) between an object and an entity (most often a person). For example, a chair affords sitting for a human.
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Affordances enable interactions between entities and objects (similarly, anti-affordances prevent or reduce interactions).
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The presence of an affordance is determined by the properties of the object and of the abilities of the entity who's interacting with the object.
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Signifiers are signals, communication devices. These signs tell you about the possible actions; what to do, and where to do it.
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Signifiers are often visible, but invisible (secret) signifiers do exist, like clicking a YT video to play and pause it, or double-clicking it to full screen it. Sometimes very useful features are "wasted" because they are very difficult to discover; consider making signifiers visible if possible.
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Sometimes it's good design to have a signifier but hide the affordance so that it only reveals itself to the intended user, e.g. a door handle that isn't grab-able, but pops out when it senses the key nearby.
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Conceptual models are (highly simplified) explanations of how something works. They are useful for predicting how something will work and what to do in case something goes wrong.
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People form conceptual models all the time. Once you interact with an object, you form a conceptual model of how it works. It's the responsibility of the designer to help the user form a useful model. The best conceptual models can often be inferred from an object itself.
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Designers have a clear conceptual model when designing the product, but users cannot talk with the designer to understand their design model, so they rely on the product's system image to form a user's model. A system image is whatever information is conveyed by the product. Information such as its shape, form, signifiers, affordances, and documentation in manuals.
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Whenever an object has external labels (e.g. labels added by the user), that's a sign of poor design.
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(highlight:: Gulf of Execution, the mental state where users figure out how to execute
Leads to the concept of discoverability
How do I know what I can do?
What actions are possible? What are my alternatives? What can I do now? How do I do it?)
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(highlight:: Gulf of Evaluation, the mental state where users figure out the response to an action taken
Leads to the concept of feedback
How do I know what happened?
What happened? Did it work? What does it mean? Is this OK? Have I accomplished my goal?)
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(highlight:: Two difficulties of using a product are
lack of discoverability (knowing what to do), and
lack of feedback (knowing what happened))
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The two gulfs connect the user's goal ("What do I want to accomplish") with the state of the world (the world is where actions and everything else occurs). When users have difficulty crossing the gulfs, it's a sign of bad design.
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Crossing the gulfs involves users (consciously or unconsciously asking themselves a series of questions. These seven questions to cross the gulfs serve as a helpful checklist when designing something:
What do I want to accomplish?
What can I do now?
How do I do it?
What happened?
What does it mean?
What are my alternatives?
Have I accomplished my goal?)
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User testing is incredibly important. You should do it early to collect feedback before you start building
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Instead of explaining your design, show it to people and let them try it. Stand back and let them know your job is to improve it and you want their help and honest feedback.
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When someone asks “would it do X”? Don’t answer the question, but instead ask “what would you like to see?” This way you capture valuable ideas.
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Sketching is cheap. Engineering is expensive. Start on paper and get feedback by testing the design on others.
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A wireframe shows the basic information and placement of different elements. Flows are sequences of wireframes. Flows create a UI story in much the same way a comic strip tells a story.
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Predictable Targets is at the confluence of Discoverability, Visibility, and Stability. These three principles are vital to people's comfort and success with visual interfaces.
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Predictable Target should appear high on your list of mandatory rules, only to be violated when it can be proven that another consideration, in a particular circumstance, will result in even greater productivity.
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What do most buyers not want? They don't want to see all kinds of scary-looking controls surrounding a media player. They don't want to see a whole bunch of buttons they don't understand. They don't want to see scroll bars. They do want to see clean screens with smooth lines. Buyers want to buy Ferraris, not tractors, and that's exactly what Apple is selling.
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If you keep your customers happy, they will become unpaid ambassadors for your product. Or, conversely, unpaid disparagers of your products. Ask yourself, what do you put your own faith in, manufacturers' puffery or experienced users' amazon reviews?
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