Information Technology Reference
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Fig. 6.7 The Tower of Hanoi puzzle. In this picture, two towers of disks are shown here, but
only one tower is normally used. The goal is to move a tower, disk-by-disk, to the far peg. The
tower on the left would be easier to work with because the disks are easier to tell apart than the
disks on the right, and because there are fewer disks (five vs. six). An example tower to play with
is on the topic's web site
to perform, and the constraints are relatively clear. It is easy to see the state of the
disks, and it is basically easy to judge how close you are to the goal state. It takes
effort to solve the puzzle, but people can generally solve it, particularly for three or
four disks.
6.3.1 The Importance of Problem Solving
Problem solving occurs when users do not know what to do next. This happens
when they are learning. Novice users will learn a lot, and expert users will learn in
novel and unusual situations. When an expert sees a new type of fault or a novel
combination of faults they will normally have to resort to problem solving. They
have to function at Rasmussen's (
1983
) knowledge level, using knowledge in a
problem solving manner, using strategies such as trial and error, for example. In
the Tower of Hanoi, the user does not know the full sequence of moves, so they
will have to do some problem solving. Some users will reason about the problem
in their head, and consider what moves are possible and where this will take them.
Other users will start by moving disks; it is a little easier to study how these users
problem solve because their behavior is more visible. In both cases, their initial
behavior will be slow and effortful. As they learn to do the task, however, their
performance becomes faster.
6.3.2 Examples of Problem Solving
When you are installing software, you might know the goal state, and you might
even think you know the starting state, but get into trouble because you don't have
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