10. Output devices
Text - Graphics - Sound
Purpose
Give the user the perception of the situation
- What to do - choices
- State of the system
- Results of the info processing
Visual feedback
- tell user what is the situation
- how much processing has occured (time line)
- signify the need for input
- confirm input
- tell that the input was unsuitable
Think of some interface:
- How does the system let you know that it does not understand your input?
- How does the system indicate that it cannot accept input at the moment?
- How does the system indicate that it needs your input in some specific form?
Visualization
Purpose is to give the user understanding of some complex phenomena.
Basic data -- representation
- model - based visualization. computer produces the data and gives a represenation
- visualization of external data - statistics (Statview - Jump)
Visualization requires mapping between the data and the representation.
Easy to change the mapping (in principle).
User can control the representation.
Examples
Word has different views at the text
Excel can give diffenent views at the data
When selecting visualization styles following factors have to be considered
- The amount of data
- The distribution of data
- The source of data
- Classification
Sound Output
Suitable in e.g. following situations
- Sound complements visual interface
- Attention is required on the screen
- Alarm-situations
- Data sonification
- Algorithm animation
Simple techniques for attaching standard or custom sound to standard events (Macintosh or Windows). Can be extended using sampled sounds.
Exercise:
- What would be suitable sound for a e-mail system.
- In which situations sound could be used.
Suggestions
- A short message
- A long message
- A message to an empty mailbox
- A message to a full mailbox
- Mail from a friend
- Mail from office
Example :
Sonic finder for the Mac adds sounds to actions on the Mac Desktop.
See figure 12.4.
Speech Output
Two techniques
- Concatenation (of prerecorded phrases)
- Synthesis-by-rule (text or phonemes to speech)
Uses
- Customer services
- Mail-order service
- Announcements (trains .. )
- Automatic reader