At the beginning of each run, the subject had sufficient time to locate and fixate the fixation point; then the scanning started.
While they fixated on the fixation point, a critical figure was flashed on the screen at the same location as that used for the saccade condition.
Finally, we measured pupil diameter to obtain an independent index of autonomic arousal [15] (eyes open and loosely fixated on a fixation point in both rest and meditation blocks) to determine if there were group differences in autonomic arousal during the task.
For baseline trials, stabilometric activity was recorded while the subject fixated on the fixation point without visual stimulation).
On each trial, subjects fixated a central fixation point for 1 s, followed by the appearance of the two pictures on left and right sides of the screen for 1 s ('choice phase').
Monkeys fixated a red fixation point (0.1° in diameter) on a grey background (21 cd/m) presented centrally on a 20-inch analogue cathode ray tube monitor (85 or 110 Hz, and 1600 × 1200 or 1280 × 1024 pixels, 57 cm from the animal).
Participants were asked to keep their eyes fixated at the fixation point and press as fast as they could, with their right hand on the numeric keyboard, a '1' when the line segment was vertical or a '2' when the line segment was horizontal.
The subject has to fixate a set of centrally positioned fixation points during the measurement.
The participants' task was to fixate on the fixation point, to remember the target position, and to make a saccade towards the remembered target location as soon as the fixation point disappeared from the screen.
To assess participants' ability to estimate the relative length of horizontal vs. vertical dimension of critical figures (rectangle, Kanizsa) while their eyes remained stationary, participants were also given fixation trials where they were only required to fixate on the fixation point without making a saccade.
Monkeys were trained to fixate a red fixation point (FP, 0.1° diameter) on a grey background (38 cd/m) presented centrally on a 20-inch analogue cathode ray tube monitor (110 Hz, 1600 × 1200 pixels, 57 cm from the animal).
