Schematic representation of the phases of the behavioral paradigm.

<p>At the beginning of the trial the cat has to direct its gaze to a green fixation point projected in the center of a CRT monitor (refresh rate 100 Hz). Then, the animal has to maintain fixation within an acceptance window for 500 ms (fixation phase). If the fixation phase is successfully accomplished, a static random dot pattern appears (at 0 ms), and it remains on the screen for 200-500 ms (static stimulation phase). After this, the dots of same static pattern start to move coherently in a radial center-in or center-out direction (optic flow, dynamic stimulation phase, 1000 ms). As can be seen in the figure, the animal has to hold fixation throughout the stimulation phases. If it manages to do so, the trial is accepted, and the animal is rewarded with a few drops of mashed cat food (reward phase, 500 ms).