Dr. Donelian wants to reduce his students' perception that psychological experiments merely document the obvious. His best strategy would be to ask the students to

I believe the answer is: Predict the outcomes of experiments before they are told the actual results.

By making them predicting the outcome of the experiment, dr. donelian would expose them with the fact that their prediction would often be wrong. After experiencing this, the students would no longer see the experiment as 'documenting the obvious'