UI terminology or metrics

This encyclopedia contains extremely valuable information about UI design and related topics. [[1]]

Here is a list of proposed UI terminology/metrics I thought the UI group may advocate in our discussions.

Perceptual Analysis

Structure – How does the location of design features and tools, such as menus, or buttons affect the user's ability to navigate the UI and understand the function of the visual space? (This does not mean cursor navigation, only visual.)

Identifiability – How easily can the user recognize an icon or interface widget?

Tool and icon consistency – Does the interface use the same or similar widgets or tools for similar tasks? Do they have visually consistent iconography?

Visibility, legibility and language – How easy is it for the user to visually process the current task? Does an icon accurately invoke an image response for the user, (ie will a user associate an icon with the correct command)? Is the language universally understood? How do color, contrast and size affect the legibility of the words or icons?

Visual and Auditory Feedback – Does performing a task result in efficient user feedback? ie opens a dialog, beeps, invokes a drop down menu

Scan paths and search patterns – If a user is looking for an unknown command or object, does the interface present an intuitive eye scan path for the user to visually search for the desired command? Does color or shape affect where the user looks?

Cognitive Analysis

Decision Processing ie Hick's Law – The time it takes for a user to make a decision as a function of all possible choices. How efficiently can the user reach the desired task/outcome given the current interface options?

Consistency – Does this task/process perform similarly to other features?

Working Memory Burden – How much does the user have to remember during the current task? How many memory channels (aka multiple tasks) must the user balance during a task? Short term memory and channel capacity for the human brain is limited to 7+-2 items ("magic number 7"). A user may only remember the 7 previous menu items, 7 previous tasks they performed, or will only be able to think about 7 tasks in parallel. Actual channel capacity depends on the type of process involved so limiting working memory burden to 5 items will satisfy the majority of users, but reduce the potential complexity of the task.

Long-term Memory Burden – How much does the user have to remember from previous user iteractions? Low long-term memory burden results in higher efficiency only if the interface is intuitive. Large long-term memory burdens negatively impacts learnability.

Efficiency – How quickly can an experienced user perform a known task?

Intuitivism – How intuitive is the design such that an experienced user can re-learn a process quickly?

Learnability – How intuitive is the design such that a new user could understand how to perform a given task?

Error prevention – Does the interface have a means to prevent cognitive error in choosing options? Does this method reduce user functionality (ie do we restrict the user's options to prevent them from doing something most users don't want to do)?

Error recovery – Does the interface have a means for the user to correct errors?

Motor-function Analysis

Cursor navigation efficiency ie Fitt’s Law – the time required for a cursor to rapidly move to a target area, as a function of the distance to the target and the size of the target.

Steering efficiency ie Accot-Zhai Steering law – How long does it take to navigate through a 2-dimensional plane without leaving a specified domain? For example, some hierarchical drop-down menus require the user to stay within the domain of the menu or the menu closes; this law estimates the time it takes to navigate to a second level or higher level menu option. Due to the rarity of menus and UI tools with such criteria, the relevancy of the steering law in most UI's is questionable, but the underlying principle, the difficulty in navigating through specific complex domains, is important.

Interaction type efficiency – How time efficient is the given interaction method? Does the user have to use multiple methods? Interaction methods could be: point and click, point-drag, single click, multi-click, right click, middle click, scroll wheel, on-mouse-over, keyboard, Ctrl+keyboard, Tab navigation, Alt+keyboard, and/or arrow key navigation. For example, scrolling could be performed by mouse wheel, or by point-drag; short distance scrolling is most efficient using the mouse wheel while point-drag is most efficient for long distance scrolling.