Human-computer Interaction

• Vision, hearing, and touch are the most important senses in HCI. The fingers, voice, eyes, head, and body position are the primary effectors.
• The sound we perceive is (selectively) filtered, which is illustrated by the cocktail party effect: we can notice our name spoken out in a noisy room.
• Emotion involves both physical and cognitive events. Our body responds biologically to an external stimulus, and we interpret that in some way as a particular emotion. That biological response (affect) changes the way we deal with different situations, and this has an impact on the way we interact with computer systems.
• Inappropriate placement of controls and displays can lead to inefficiency, frustration, and sometimes dangerous situations.
• The system's design needs to fit the user's size, position (sitting/standing), comfort, and safety.
• It is no longer sufficient that users can use a system; they have to want to use it as well.
• The sense of flow occurs when there is a balance between anxiety and boredom.
• If we want people to want to use a device or application, we need to understand their personal values.
• Metaphors are used quite successfully to teach new concepts in terms of ones that are already understood. Features:
  • Visibility of the objects of interest.
  • Incremental action at the interface with rapid feedback on all actions.
  • Reversibility of all actions, so that users are encouraged to explore without severe penalties.
  • Syntactic correctness of all actions, so that every user action is a legal operation.
  • Replacement of complex command languages with actions to manipulate directly the visible objects.
    Psychological approach: model-world metaphor (direct engagement): In a system built on the model-world metaphor, the interface is itself a world where the user can act, and which changes state in response to user actions. The world of interest is explicitly represented, and there is no intermediary between the user and the world. Appropriate use of the model-world metaphor can create the sensation in the user of acting upon the objects and task domains themselves: direct engagement.
• The golden rule of design: Understand your material: computers (limitations, capacities, tools, platforms) and people (psychological, social aspects, human error)
  • To err is human: It is the nature of humans to make mistakes, and systems should be designed to reduce the likelihood of those mistakes and to minimize the consequences when mistakes happen.
• Universal design principles

1. Equitable use: useful to people with a range of abilities
2. Flexibility in use: choice of methods of use and adaptivity to the user's pace, precision, and customization.
3. Simple and intuitive to use
4. Perceptive information
5. Tolerance for error
6. Low physical effort
7. Size and space for approach and use