3.2: Usability Principles

Question 1

What are the usability concepts

Answer 1

1. affordance
2. signifiers
3. visibility
4. mapping
5. feedback
6. constraints
7. metaphors

Question 2

provide a meaning and example for each of the usability concepts

Answer 2

1. affordance
   - perceived and actual property of an object that allows user to perform action
2. signifiers
   - signal that communicates how to use an object
3. visibility
   - how easily a feature is seen
4. mapping
   - relationship between control and result
5. feedback
   - information that is sent back to the user about action performed
6. constraints
   - limits to the perceived operation of device
7. metaphors
   - visual, actions, and procedures that exploit specific knowledge that users have in other domains

Question 3

what are conceptual models and mental models? What are the differences between them?

Answer 3

conceptual
Simplified explanation or framework for understanding how something works. Formal, structured & logical.

mental
Models people already have of themselves, others, environment, and things they interact with. Informal, incomplete and sometimes erroneous.

differences
Conceptual: Formal, structured & logical.
Mental: Informal, incomplete and sometimes erroneous.

Question 4

What is the system image?

Answer 4

information conveyed by the product that links the conceptual image to users mental image

Question 5

What is the gulf of evaluation and execution

Answer 5

gulf of evaluation
It is the amount of effort a person must exert to interpret the results of their action or state of a system.

gulf of execution
It is the amount of effort a person must exert to tell a system what to do.

Question 6

How do you bridge the gulfs

Answer 6

apply the usability principles
affordance
feedback 
good conceptual model
visibility
constraints

Question 7

Apply Norman’s 7 stages of action to creating a new directory using the command line.

Answer 7

1. forming of goal
2. forming the intention
3. specify sequence of action
4. execution of action sequence
5. perceive state of the system
6. interpret the perceived state
7. evaluate the interpretation