Answer:
Dependent.
Step-by-step explanation:
In a scientific experiment, there's two kinds of variables: independent variables and dependent variables. The value of the dependent variable depends on the value of the independent variable. The dependent variable is the variable that is being tested during an experiment. The researcher will change the independent variable and register the subsequent changes in the dependent variable.
In this experiment, the independent variable was the researcher, and the students' emotional expressions were the dependent variable. Changes in the independent variable (whether the researcher was present or not) led to changes in the dependent variable (the student's emotional expressions).