In an experiment, there are two kinds of variables. The independent variable is the variable that is believed to affect another variable. The dependent variable is the variable that is going to be impacted. Thus, the belief going into the experiment is that changing the independent variable will cause the dependent variable to change.
In your question, there is too little information to determine which variable is dependent and which is independent. Either variable could fit either role, depending on exactly how the experiment is conducted. Let us see why this is so.
In one possible experiment, how long it takes the subject to step away will be the independent variable and the distance between the subject and the interviewer (after the step) is the dependent variable. In this experiment, the interviewer will presumably stand very close (a set distance that does not change) to the subject. Researchers will then time how long it takes for the subject to get nervous and step away. Once the subject steps away, they will measure how far the subject steps. The idea is that the amount of time the subject waits to step away will affect how far they step. Perhaps the people who step away soonest will also step farthest.
The experiment could be changed, though, to make the distance between the two the independent variable. In this experiment, the interviewer stands at various distances from the subject. The researchers then measure how long it takes the subject to step away. The researchers would change how closes the interviewer stands and they would expect that this would affect how soon people stepped away. This would make the distance the independent variable and the time taken to step away the dependent variable.