Here is what I propose:

"motor left video": "left button press (visual)",
"motor right audio": "right button press (auditory)",
"motor right": "right button press",
"right-left": "right-left button press"
"checkerboardV": "vertical checkerboard",
"x": "vertical-horizontal checkerboard",
"computation video": "computation (visual cue)",
"computation-sentences video": "computation (visual cue) - sentence reading",
"aa": "right button press (visual cue) vs visual sentence reading",
"ab": "visual instructions",
"ac": "visual - auditory instructions",
"ad": "visual instructions - checkerboard",
"sentences video": "sentence reading",
"af": "sentence reading - checkerboard"

HTH