Data acquisition using video-oculography

The saccades were recorded by an infrared video-oculography (VOG) device (EyeSeeCam vHIT, EyeSeeTec Fürstenfeldbruck, Germany), that was linked to a MacBook Pro 13” (OS X Version 10.9.5, Apple Inc.) equipped with the EyeSeeCam software (EyeSeeCam VOG HIT System Reversion r3429 and r3444, EyeSeeTec Fürstenfeldbruck, Germany). The EyeSeeCam provides an infrared-illumination and six depth-of field inertial sensors, a laser calibration module and a head mask resembling swimming goggles. The camera is mounted on the head mask above the left eye and records the eye movements through a transparent mirror surface. The fixation of the camera by a ball joint allows to center the pupil. The manual focus can be adjusted by a rotatable lens. The video image is sampled at 220 Hz (every 3.6 ms). The target displacements were predetermined by the software at 5°/15°/30° horizontally and 5°/10°/20° vertically.