The study entitled "Virtual Reality and notion of control in the treatment of acrophobia by exposure to virtual environments: comparative study," whose principal investigator is Dr. Eric Malbos and whose sponsor is Qualissima, is now open to recruitment. The objective of this study is to evaluate the effectiveness of the control of the virtual environment in the Therapy by Exposure to Virtual Reality in acrophobic patients on their symptoms and psychophysiological responses in situations of height in Virtual Reality. 20 healthy subjects and 40 acrophobic patients will be included.