In this experiment, you will first be asked to solve the following
puzzle:

There are three vertical pegs on a board, which are named Tower A,
Tower B, and Tower C from the left to the right.  Initially, there are
several disks of different size on one of the pegs (the 'Source
Tower') with the configuration that each disk lies above the disk(s)
bigger than it is.

YOUR TASK is to transfer those disks to another peg (the 'Target
Tower', which is coloured BLUE) by MOVING ONE DISK AT A TIME to one of
the towers other than the tower on which the disk lies, and by
following the RULES:

(a) You CANNOT PUT A DISK ONTO A DISK that is SMALLER than itself, and 
(b) you CANNOT MOVE A DISK ON WHICH ANOTHER DISK LIES (i.e., you can only
move the topmost disk of a tower).

As the problem is presented on a computer, you will have to use the
mouse to move disks between towers.  

[The program can be used in two separate modes:  

In SOLVE MODE]  
You can move disks between towers by using the mouse cursor to
indicate from and to which tower you want to transfer a disk.

[In SOLVE MODE, each moves counts towards your move total and you can only solve the problem whilst in this mode.

By pressing and holding the <SHIFT> key, the program switches into
EXPLORE MODE.  In this mode, you can move the disks between towers,
but the moves are not counted as part of your solution. This allows
you to explore the consequences of moves without them contributing
towards your total move score.

As soon as the <SHIFT> key is released, the program switches back into
SOLVE MODE and restores the problem to the state at which you switched
into EXPLORE MODE.

(You can use EXPLORE MODE as often as you want, or not at all.)]

To familiarize yourself with the software interface, you will now
receive a simple PRACTICE TRIAL.
  
