2.4. Ocular measurement
Eye data were measured using an Eyelink 1000 Plus (SR Research, Mississauga, ON, Canada). An elliptical fitting pupil detection technique was used to record data from the left eye at 1000 Hz. The lighting in the laboratory was kept consistent throughout the experiment to control ambient brightness. Visual stimuli were shown at a screen resolution of 1440 x 900 pixels (60 Hz refresh rate) at a distance of 60 cm from the eyes to the LCD monitor. A 9-point calibration and validation procedure was used to calibrate gaze position and pupil measurement. Spontaneous EBR and pupil diameter were measured during the MIST task and Ocular tasks