3) Robustness yet requisite unpredictability. Artefacts
should maintain an acceptable level of (physical and
interactive) robustness, while introducing a requisite level
of unpredictability in order to stimulate engagement
through mystery. Dalsgaard terms this as designing for
‘inquisitive use’ [9]. Bowers [3] in his analysis of the work
of designs such as the drift table [13], argues that they are
appealing because they have interactivity which combines
the right kind of unpredictability (so users ‘steer’ the pieces,
rather than control them) with known states that are easy to
get (back) to or recognise if troubles occur.