In the test session (see upper part of figure), respondents had to judge which of the four figures on the right corresponded to the figure in the left frame. For example, the third test item (PF & C) in the left frame shows how a piece of paper is folded and cut out, while in the right frame there are 4 unfolded pieces of paper. The question was, which of the four unfolded pieces of paper in the right frame corresponds to the one folded in the left frame? The correct answers for the three test tasks are: 2, 3 and 4. The training session items in a stepwise presentation showed the solution principles (see lower part of figure).