The design of this study is a 2x2 factorial design, manipulating the independent variables "Number of bystanders" and "Gender" to examine their effects on the dependent variable.
The design of this study appears to be a factorial design, specifically a 2x2 factorial design. In a factorial design, researchers manipulate two or more independent variables, studying their individual and interactive effects on the dependent variable (DV). In this case, the independent variables are "Number of bystanders" with two levels (0 and 10) and "Gender" with two levels (Male and Female).
The DV is "Percent of participants who offered help to a stranger in distress." The inclusion of different levels for each independent variable allows the researchers to examine the main effects of each variable independently, as well as any potential interaction effects between them. This type of design provides a comprehensive understanding of how multiple factors influence the observed behavior.