User Interface Design. Two major opportunities for design during software development. &. Motivation.
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Three important goals of UI design are to develop software that is:
Easy to use
These three goals definea hierarchy of needs: If it worksI’ll consider it. If it’s easy touse I will be pleased. If it’senjoyable I’ll develop anemotional attachment.
Easy to use
u = 2300
h = 3.5
s = $28
y = 3
2300 * 4 * $28 = $257,600
2300 * 3.5 * 236 * $28 * 10% = $5,319,440
Task analysis involves observing users in order to understand their needs. How do they currently approach their work? What services will they need from the system in order to accomplish their work? The output of task analysis is the information needed to write use cases: categories of users (roles), the goals associated with each type of user and workflows or scenarios leading to goal resolution.
Function analysis looks beyond current work practices to identify the purpose of the observed user activities. For example, task analysis might reveal receptionists making phone calls to patients reminding them of upcoming appointments. The task here is calling patients. The function is to remind patients of an upcoming appointment. Email and text messaging are alternate methods of accomplishing the task.
You and your buddies are driving up a Colorado mountain road on a hot summer day when your car, a ‘85 Chevy Impala,
starts to overheat. There is no room to
pull over. One of your friends suggests turning on the heater. Another laughs
at the idea, noting you want the car
cooler not hotter. What do you do?
When someone asks for an “intuitive” interface what they usually want is a familiar one. Human instincts aren’t of much help when interacting with most programs.
Interfaces are easy to use and easy to learn when they are familiar; when they leverage what we already know; when they provide experiences that are consistent with past experiences.
Is the iPad intuitive or familiar? Is the iPad instinctive to use? Children seen to have no problem using an iPad. Does that make it instinctive?
Simple and natural dialogs
Safe exploration and forgiveness
Use shortcuts and accelerators
Minimize the cognitive costs of your application
Minimize user’s memory load
Help and documentation
Exploration is one of the best ways to learn a new system.
Encourage, or at least don’t do anything to discourage, exploration. You can do this by avoiding unpleasant consequences of exploration. Users are encouraged to explore when your program is forgiving. Forgiveness means that actions on the computer are generally reversible.
Always warn users before they initiate a task that will cause irretrievable data loss. (In a helpful way)
Make actions reversible. Provide multi-level undo
Favor direct manipulation of onscreen objects over commands.
When the user performs operations on the object, the impact of those operations on the object is immediately visible. Allow the user to feel they are directly controlling the object they are working with.
Drag and drop in IE
Changing the length ofa video clip on the timelinein Premiere
Consistency in the interface allows users to transfer their knowledge and skills from one application to another.
There are different levels of consistency:
Consistency within the current instance of your product
Consistency with earlier versions of your product
Consistency within a family of products you offer
Consistency with other products on the same platform
Consistency with user expectations
When there are conflicts, narrow-scope consistency (within an application) have priority over broad-scope consistency (other products on the same platform).
Ctrl-c for copy and Ctrl-v for paste are reflexive for most Windows users.
People like to see immediate gratification from the actions they take. (Skip the splash screen?)
Users should achieve some level of success within the first few seconds of using your software.
Many programs start with ablank document and controlsyou need to begin workingout front.
Just as financial costs are a barrier to purchase, cognitive costs can be a barrier to use. Most people don’t have the time, energy or patience to parse a complicated interface.
Most people will scan the page looking for obvious clues how to proceed. Users look for visual cues like color and form that can be immediately processed rather than invest the time it takes to read and comprehend text
Expecting users to read is such a quaint idea.
The cognitive cost of reading this email was too much for the recipient.
Consciously or unconsciously people tend to use spatial memory to find their way back to objects and commands.
Rearranging controls or menu options can disrupt spatial memory.
Spatial memory is related to consistency
Some applications will allow you to save your panel arrangement
Sorting menu commands by frequency of use isn’t always a welcome feature.