The second test is slightly luck based.
1) Sometimes the sheep that starts running is offscreen. Time starts running when the sheep appears in the screen, but the running sound starts as soon as the sheep starts running (so you have an advantage if you react by sound instead of images).
2) Sheep that appear in the upper part are much easier to catch than the ones that appear in the bottom.
Also, it seems if you manage to catch a sheep before it is onscreen you get a 0.0 sec reaction time.
(I averaged 200.2 in the first test and around 240 in the second one)