[UI] Ch1 Usability of Interactive Systems

(Designing the User Interface, Ben Shneiderman and Catherine Plaisant, Addison-Wesley, 2004, ISBN 0-321-19786-0)

• 1.1 Introduction
• HCI (human-computer interaction) began by combining the data-gathering methods and intellectual framework of experimental psychology with the powerful and widely used tools deveoped from computer science.
• UI changes many people's life
• the motor, perceptual, and cognitive foundations are growing firmer, while the social, economic, and ethical impacts are becoming clearer.
• some designers promote:
  
• persuasive technologies that change users' behavior
• multi-model or gestural interfaces that facilitate use
• affective interfaces that respond to the user's emotional state
  
• 1.2 Usability Requirements
• making a checklist of subjective guidelines: have thorough understanding of the diverse commmunity of users and the tasks that must be accomplished
• when an interactive system is well designed, the interface almost disappears, enabling users to concentrate on their work, exploration, or pleasure.
• goals:
• ascertain the users' needs
• what tasks and subtasks must be carried out
• frequent / occasional / exceptional / repair tasks
  
• ensure proper reliability
• user's trust of systems is fragile
  
• promote appropriate:
  
• standardization - common UI features across multiple app
  
• integration - file formats
  
• consistency - common action sequence...
  
• portability - potential to convert data and share UI across multiple SW and HW environments
  
• complete projects on schedule and within budget
  
• 1.3 Usability Measures
• practical evaluation
• time to learn
• speed of performance
• rate of errors by users
• retention over time
• subjective satisfaction
  
• after multiple design alternatives have been raised, the leading possibilities should be reviewed by designers and users.
• high-fidelity online prototypes create a more realistice environment for expert reviews and usability testing
  
• 1.4 Usability Motivations
• the enormous interest in interface usability arises from:
  
• the growing recognition of how poorly designed many current interfaces are
• the benefits elegant interfaces bring to users
  
• exploratory, creative, and collaborative interfaces:
• users may be knowledgeable in the task domain, but novinces in the underlying computer concepts
• their motivation is high, but so are their expectations
  
• at best, having computer vanish as users become completely when the computer absorbed in their task domains.
• provide direct manipulation representation of the world of action
• then tasks are carried out by rapid familiar selections or gestures, with immediate feedback and new sets of choices
• users can keep their focus on the task, with minimal distraction in operating the interface