How People Do Things Flashcards
Execution (action cycle)
Execution starts with a goal, then
1. Plan - intend to act
2. Specify - Think of sequences of steps to achieve goal
3. Perform - carry out specific steps
Evaluation (action cycle)
Comparing expectations with what happened
1. Perceive - observe what happened
2. Interpret - make sense of observation
3. Compare - compare what happened with what was wanted
Norman’s Action Cycle
A simplified framework for understanding human action
Gulf of Execution
The difference between the intentions of the user and what the system allows them to do
Gulf of Evaluation
The amount of effort the user must take to interpret the state of the system and how well expectations have been met
Two most important characteristics of good design
Discoverability & Understanding
Discoverability
The quality of letting the user figure out what actions are possible and how to achieve them
Understanding
The state of the user to know how the product is supposed to be used
An interface designer must understand…
Psychology and technology
Fundamental Principles of Interaction
Affordance
Signifiers
Mapping
Feedback
Conceptual model
Affordance
Relationship between the properties of the object and the capabilities of the user
Norman’s 4 principles for screen interfaces
Follow convention
Use words and graphics to describe actions
Use metaphor
Follow a coherent conceptual model
Signifiers
A mechanism to communicate where the action should take place - any mark that communicates behavior to the user
Deliberate Signifier
A signifier left intentionally, for example a push sign on a door
Accidental Signifier
A signifier left unintentionally, for example a trail left by people walking past previously
Mapping
Relationship between control elements and their results
Feedback
A mechanism to communicate the results of an action
Conceptual model/mental model
An explanation of how things work - lets the user predict how things will behave
Transfer Effects
People transfer learning of similar objects to current objects
System image
What can be derived from the interface
System image is responsible for aligning designer’s and users’ mental model
Direct Manipulation
Continuous representation of object of interest
Physical actions to manipulate system
Continuous feedback
Affords rapid learning
