Answer:
dependent variable
Step-by-step explanation:
The dependent variables is being studied or measured in the experiment or in the study. A dependent variable is a variable that is dependent on another variable in the experiment. It is the effect. When the independent variable changes, the values of the dependent variable also changes.
Thus in the context, when the experimenter manipulates the probability of the attention for slapping, the frequency of the slapping is the example of a dependent variable.