Figure 1.

Experimental setup and stimuli. A, Top view of the experimental setup. An infrared-based eye-tracker was used to measure the horizontal position of the dominant eye. An optical motion capture system recorded the 3D positions of the thumb and index tips. Stimuli were projected on a computer monitor at 54 cm from the subject's eyes and hand position rested at 34 cm from the body midline. B, Frontal view of the stimuli used in the experiments: circle represents fixation target (0.3 degree of radius); rectangles represent saccade and size estimation targets. C, Typical hand posture during the size estimation phase and passive markers (10 mm of radius) attached on the thumb and index nails.