I'm as guilty as the next guy at using a lyric sheet or chord sheet on occasion to get through gig. Though it's not something I feel chained to, it helps to have a prompt while trying a new tune. Some of my friends would like to have every aspect of any given performance we do laid out ahead of time and printed up to make it easier for everyone in the group to follow along. I've always enjoyed just getting up and playing what I enjoy without having to stick to a stick form or show. There are merits to each of these approaches and I usually try to find some middle ground compromise to appease everyone involved. I too will many times find myself closing my eyes while performing partly as a means of concentration. It helps to limit distractions. As some singers will place a hand over one ear to limit ambiant sound from interfering with their concentration. I also have a habit of keeping an eye on my fingerboard while I play thus limiting the amount of eye contact I make with my audience. Even at that there's the occasional missed fingering or slide of the bottleneck. I just muscle through as best I can. There are times when I have repeated a line that was totally improved or even a mistake on my part and have been surprised at how it seemed to come from nowhere and how I was even able to remember how to repeat it. Furthermore, I have totally lost a verse of a song at times. Though this is not a common occurence, stuff happens and for one reason or another the words just disappear. Perhaps it's due to exhaustion or dehydration. I remember being at a party and taking a small sip of some particularly potent champagne just before trying to sing a Lazy Larry song, Who Said I Was A Bum, to Utah Philips. It must have been the bubbles because I could not remember a lick after that sip. I have often finished performing a set soaking wet and feeling totally beat. It depends on the gig, who I'm performing with, what kind of material and instrumentaion I'm working with. This process we're all discussing here is called learning. There are as many stages as there are those caught up in the act of trying. Can any of us say we've arrived at the end of this process? I don't think so. My songs always seem to change even as I change and grow and discover more about this thing I'm caught up in, life on the planet.