a simple shock question from the mechanically challanged

[MLC]

i almost never ride two up but i did at ROT with screamin and we bottomed out the rear on one real good bump. i bought a shock wrench to carry and thought i'd adjust the rear and try it out. my question is which direction stiffens the shock. i tried a couple notices in each direction and i cant see or feel any difference. there are no markings on the shock and neither the shop or owners manuals say which direction (clock wise or counter clock wise).