In order to obtain the data, have the subject sit in a chair 18 inches from the screen.  Start recording and have the volunteer shift gaze from one side of the computer screen to the other multiple times and stop in the middle of the screen.  Once completed, stop recording.  Click and drag over the portion that corresponded to the volunteer’s gaze of the computer length that includes the left and right side of the screen.  Adjust the amplitude scale according to the subject's gaze.  Assuming center is 0%, data of -50% or lower and 50% or higher will be considered off screen.  Once this is set up, have the student watch the control video.  Take note of how many times the gaze is off the screen.  Repeat with each lecture type