I know the thread is a bit old but please don't use the perch method, I don't understand why so many people believe it will work. If anything it will just give the bird even more reason to attack you, I agree with one of the earlier comments. Training is the only way to get through this, before I adopted my male bare eyed cockatoo (his history is for the most part a mystery, but the bit we do know is certainly disturbing) he attacked other members/volumteers at the rescue centre and only responded to me. The only problem was that he would bite me in the face and obviously carve my fingers whenever it was time for me to go. So first thing we did was make sure he was in his cage before I arrived, from there on I started working on getting him to accept treats. Once he started accepting the treats we moved to clicker conditioning (click = treat), as he learned what the click meant I started with target training. I allowed no physical contact during that first day and still remained focussed on training every other time he saw me. It will however be different for you and your cockatoo, I don't believe in using medication in CURING aggression. For now the best thing would be keep him in his cage when you have visitors and just work with him while he is in his cage. It's important that you remember that every time he bites you, there will be damaged done to your relationship so a bite is something you should avoid at all costs. If however he seems nervous and/or aggressive with you NEAR his cage then you have to star with that first and take things from there. Once he's accepting of you and has the basics down (such as target training) then you can use the same methods when socializing him with other people. Good luck and let us know how things go!