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