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Interaction Design Basics

Interaction design focuses on creating engaging interfaces with well thought out behaviors. Understanding how users and technology communicate with each other is fundamental to this field. With this understanding, you can anticipate how someone might interact with the system, fix problems early, as well as invent new ways of doing things. 

Best Practices for Designing Interactions

Consider these qualities and associated questions when creating digital products that have an interactive element:

Questions to Consider when Designing for Interaction
Define How Users Can Interact with the Interface
  • What can a user do with their mouse, finger, or stylus to directly interact with the interface? This includes pushing buttons, dragging and dropping across the interface, etc.
  • What commands can a user give, that aren’t directly a part of the product, to interact with it? An example of an “indirect manipulation” is when a user hits “Ctrl+C”, they expect to be able to copy a piece of content.
Give Users Clues about Behavior before Actions are Taken
  • What about the appearance (color, shape, size, etc) gives the user a clue about how it may function? These help the user understand how it can be used.
  • What information do you provide to let a user know what will happen before they perform an action? These tell users what will happen if they decide to move forward with their action. This can include meaningful label on a button, instructions before a final submission, etc.
Anticipate and Mitigate Errors
  • Are there constraints put in place to help prevent errors? The Poka-Yoke Principle says that placing these constraints forces the user to adjust behavior in order to move forward with their intended action.
  • Do error messages provide a way for the user to correct the problem or explain why the error occurred? Helpful error messages provide solutions and context.
Consider System Feedback and Response Time
  • What feedback does a user get once an action is performed? When a user engages and performs an action, the system needs to respond to acknowledge the action and to let the user know what it is doing.
  • How long between an action and a product’s response time? Responsiveness (latency) can be characterized at four levels: immediate (less than 0.1 second), stammer (0.1-1 second), interruption (1-10 seconds), and disruption (more than 10 seconds).
Strategically Think about Each Elements
  • Are the interface elements a reasonable size to interact with? Fitts’ Law says that elements, such as buttons, need to be big enough for a user to be able to click it. This is particularly important in a mobile context that likely includes a touch component.
  • Are edges and corners strategically being used to locate interactive elements like menus? Fitts’ Law also states that since the edge provides a boundary that the mouse or finger cannot go beyond, it tends to be a good location for menus and buttons.
  • Are you following standards? Users have an understanding of how interface elements are supposed to function. You should only depart from the standards if a new way improves upon the old.
Simplify for Learnability
  • Is information chunked into seven (plus or minus two) items at a time? George Miller found that people are only able to keep five to nine items in the short-term memory before they forgot or had errors.
  • Is the user’s end simplified as much as possible? Tesler’s Law of Conservation notes that you need to try to remove complexity as much as possible from the user and instead build the system to take it into account. With that said, he also notes to keep in mind that things can only be simplified to a certain point before they no longer function.
  • Are familiar formats used? Hick’s Law states that decision time is affected by how familiar a format is for a user to follow, how familiar they are with the choices, and the number of choice they need to decide between.