Answer:
The answer is experimental design.
Explanation:
In experimental designs, the researchers have control over all the factors of the research. It also allows researches to make predictions about the results and analyse the effects of the variables once the experiments have been carried out.
In this case, the researches are attempting to test the effects of showing both violent and non-violent images (independent variable) to expert and non-expert, in order to see the results (dependent variable).
