People who knew L. Ron Hubbard, before he started writing Dianetics knew him as a master hypnotist. An old time associate of his named Forrest J. Ackerman had this to say about the man:
“And what I particularly remember about his appearances there was an evening of spectacular hypnotism when hypnotized just about every kid in the club. I remember he gave one young man a... what would you call it... In any event, the boy was convinced that cupped in his hand, he held a little tiny Kangaroo that was hopping around and I remember he came over and showed the Kangaroo to me”.
So Hubbard was good enough hypnotist to convince a person that they had a kangaroo in their hand! Also if you compare the following video and this article from wikihow you can clearly see the similarities. Notice how in both the article and the video they have the person that is being audited/hypnotized close their eye's this is a common occurrence in both Dianetics, Scientology and of course in hypnotism. Also they both tell the person that they will remember everything but that's not necessarily true; it works as a "waking suggestion" which can cause the person being audited/hypnotized put more trust in the auditor/ hypnotist. Also, yet another similarity is that they both have the person then imagine a time or place of being happy or sad. In Dianetics, then tend to concentrate on a sad or negative time but happy memories are also used in some cases.