“Welcome. In this task you will see a number of figures appear on the computer screen. After some of these figures, a
lightning bolt will appear. Your task is to try to predict after which figures the lightning bolt will occur. Some figures
will predict this occurrence better than other figures. With each figure presentation, a scale will also appear at the
bottom of the computer screen, on which you can indicate your prediction. This scale runs from 0 to 10, where 0 means
“Certainly no lightning bolt”, 5 means “Maybe”, and 10 “Certainly lightning bolt”. Using the left and right arrows on
the keyboard, you can control your rating. Upon hitting the key, you will either see the lightning bolt appear
or else the screen will remain black. Hence, you can infer the correctness of your prediction. Then the next figure will
appear, and you will have to make a new prediction. Initially, this task may seem a game of chance, but the aim is
that you gradually learn the relationship between the different figures and the occurrence of the lightning bolt. Press
to start the experiment.”