Handheld Devices

• Wide variety of shapes

• Often used in an "eye-less mode"
   (due to distraction, adverse light conditions, practice)

        High-tactility keypads necessary
         (elevated keys, sufficient distance between keys, material that feels different than chassis)
         [audio feedback too much dependent on ambient noise level !]

• Saving screen real estate has high priority

- Icons
- Overlapping controls (which automatically appear and disappear)
- Highly targeted information provision (e.g., through personalization)

• Menus should be relatively flat
  Vertical screen size thereby does not seem to play a major role, unless it is very small (i.e. one line only)

• New interaction paradigms possible

Motion-invariant displays
Touchscreen dragging
Hand mirror metaphor
Keyhole/Flashlight Metaphor

Texting: low cost, low intrusion on receipient and others, turn-taking, privacy

Using a handsfree phone while driving is not much safer than using a handheld phone Speaking to other people by phone places a sufficiently dangerous cognitive load on drivers (4 times higher than when talking to a passenger) Increases accident risk by a factor of 4 (equivalent to 0.08% alcohol in blood) (Texting while driving increases the accident risk by a factor of 18)