Human-Computer Interaction Module 2.2 Flashcards
When you’re designing for learnability, you have to be aware of ____________________
How people actually learn
The conventional model for human memory has two components:
Working Memory and Long-term memory
This memory is where you do your conscious thinking.
Working Memory
This memory is probably the least understood part of human cognition.
Long-Term Memory
This is the act of repeating the items to yourself, which fends off this eventual decay of working memory, but doing this requires attention. So, distractions can easily destroy working memory.
Maintenance Rehearsal
The elements of perception and memory are called
Chunks
In one sense, chunks are defined ________; in another sense, a chunk represents the _______________.
symbols; activation of past experience.
Our ability to form chunks in working memory depends strongly on how. . . ?
the information is presented.
This is remembering with the help of a visible cue
Recognition
This is remembering something with no help from the outside world.
Recall
We can think about __________ (and __________ and _________) in terms of a generalized cognitive model for how people use a computer system
learnability, visibility, efficiency
This has been one of the major goals in the evolution of graphical user interfaces over the last few decades.
Better learnability
The earliest computer interface
Command Languages
This interface presents a series of menus or forms to the user.
Menu/Form Interface
the preeminent interface style for graphical user interfaces.
Direct Manipulation
Direct Manipulation is defined by three principles
A continuous visual representation; Physical actions or labeled button presses (clicking on virtual objects and manipulating them via drag and drop type actions); The effects of actions should be rapid, incremental and reversible.
Why is direct manipulation so powerful?
It exploits perceptual and motor skills of the human machine – and depends less on linguistic skills than command or menu/form interfaces. So it’s more natural in a sense, because we learned how to manipulate the physical world long before we learned how to talk, read, and write.
3 Types of Interaction Styles
Command Language, Menu/Form Interface, Direct Manipulation
Comparison of the interaction styles in terms of Learnability?
CL requires significant learning. Users must put a lot of knowledge into their heads in order to use the language, by reading, training, practice, etc. The MF style puts much more information into the world, i.e. into the interface itself. DM also has information in the world, delivered by the affordances, feedback, and constraints of the visual metaphor. Since recognition is so much easier than recall, this means that MF and DM is much more learnable and memorable than CL.
Comparison of interaction styles in terms of Error messages?
CL and MF often have error messages (e.g. you didn’t enter a phone number), but DM rarely needs error messages. There’s no error message when you drag a scrollbar too far, for example; the scrollbar thumb simply stops, and the visual constraints of the scrollbar make it obvious why it stopped.
Comparison interaction styles in terms of efficiency?
Experts can be very efficient with CL, since they don’t need to wait for and visually scan system prompts, and many CL systems have command histories and scripting facilities that allow commands to be reused rather than constantly retyped. Efficient performance with MF interfaces demands good shortcuts (e.g. keyboard shortcuts, tabbing between form fields, typeahead). Efficient performance with DMs is possible when the DM is appropriate to the task; but using DM for a task it isn’t well-suited for may feel like manual labor with a mouse
Comparison of Interaction styles in terms of User Type
CL is generally better for expert users, who keep their knowledge active and who are willing to invest in training and learning in exchange for greater efficiency. MF and DM are generally better for novices and infrequent users.
Comparison of Interaction Styles in terms of Sychrony?
Command languages are synchronous (first the user types a complete command, then the system does it). So are menu systems and forms; e.g., you fill out a web form, and then you submit it. DM, on the other hand, is asynchronous: the user can point the mouse anywhere and do anything at any time. DM interfaces are necessarily event-driven.
Comparison of Interaction Styles in terms of Programming difficulty?
CL interfaces are relatively easy to implement. MF interfaces have substantial toolkit support; e.g., it’s easy to create an MF web site using plain vanilla HTML, or an MF Java program using nothing but Java Swing widgets like textboxes, buttons, and checkboxes. DM is hardest to program
Comparison of Interaction Styles In terms of Accessibility?
CL and MF interfaces are more textual, so they are easier for vision-impaired users to read with screen readers. DM interfaces are much harder for these users.
Regardless of interaction style, learning a new system requires the user to. . .?
Build a mental model of how the system works.
A _____ of a system is a way of describing how the system works.
model
Models in UI Design
System (Implementation) Model, Interface (Manifest) Model, User (Conceptual) Model
This model is how the system actually works.
System model
This model is the model that the system presents to the user through its user interface.
Interface Model
This model is how the user thinks the system works
User Model
. Learnability Principles
Affordances, Natural Mapping, Visibility, Feedback, Consistency
This refers to the perceived and actual properties of a thing, primarily the properties that determine how the thing could be operated.
Affordance
They are how an interface communicates nonverbally
Affordances
Mapping functions to controls
Natural MappingE
Examples of mapping?
Stove Burners, Car turn signals
An essential principle, probably the most important in communicating a model to the user.
Visibility
If the user can’t see an important control, they would have to… ?
guess that it exists and guess where it is.
Final principle of interface, this is what the system does when you perform an action. The response of a system, essentially.
Feedback
The second set of principles fall under the general umbrella of. . . ?
Consistency
Affordances and natural mapping are examples of a general principle of learnability:
Consistency
This rule is often given the hifalutin name the Principle of Least Surprise
Consistency
Three Kinds of Consistency
- internal consistency within your application;
- external consistency with other applications on the same platform; and
- metaphorical consistency with your interface metaphor or similar real-world objects.
One important area of consistency is in _______– where controls and information are displayed on the screen. This is the reason that menu bars appear at the top of the screen (or window).
layout
An important kind of consistency that entails using the same terms throughout your user interface
Consistency in Wording
This consistency in wording is important too. In other words, speak the user’s language as much as possible.
External consistency in wording. (If the user speaks english, the interface should also speak english, don’t use technical jargon that only you can understand)
External Consistency also comes from following. . . ? Many platforms have coded his into a rulebook,
Platform Standards
This is one way you can bring the real world into your interface.
Metaphor
This person finesses the issue of consistency still further. His argument is that consistency should not be treated as a sacred cow, but rather remain subservient to the needs of context and task.
Jonathan Grudin (in Case against Consistency)
Learnable interfaces should clearly communicate. . .?
The correct mental model to the user
Learnable Interfaces should?
- Use affordances, natural mapping, visibility
Consider metaphors. - Be consistent internally, externally, and metaphorically.
- Prefer knowledge in the world over knowledge in the head.
