Recent studies say that there can be some short term memory loss. However, that may be filtered thru the fact that many people have only average to poor short term memory anyway. I can remember things better a day later than I can an hour later. I think cannabis use just makes your existing level of retention more obvious to you. And look at the facts that research has shown that cannibiods help repair damage to the brain from diseases. Seems contradictory that it would do damage at the same time.