Hi Jaewon, I have trouble of getting the pupil size (either pupil diameter or area) during the task. I only manage to get the eye position data (x and y) using either eye_postion() or get_analog_data(). For the pupil size, I am sure Eyelink is saving it and I set the Eyelink to send the pupil data in diameter. Is there any function I can use to get 3- column data with x, y and the pupil size?by haozhou.jiang - Questions and Answers