I have thought about this for a while and have come to a semi conclusion but what would happen with someone with amnesia and they sinned and they forgot how are they able to properly confess. I got this idea after watching memento and just was wondering about it.
Any type of forgetfulness, whether willfull or not, represents how the mind cannot grasp or understand itself due to our corruption.
And if you look at some of the prayers in Orthodoxy, the pre-communion prayer of St. John Chrysostom immediately comes to mind, we ask for God's forgiveness of our transgressions, of word and of deed, of knowledge and ignorance.
After a pentitent's confession, the priest says that all I have confessed, those things which I have said or those things which I have forgotten to say, is forgiven. My priest also asks who can truly enumerate all his sins?
My point is that enumerating each and every sin accurately is not nearly as important as God's grace to live and to sin no more. But one should not use that as an excuse to make his sin known before his priest. Does anything I said make sense?