It depends on what you’re trying to remember. The biggies for enhancing memory (on a single trial; let’s not worry about types of learning) are, in no particular order:
1. Attention
2. Arousal
3. Salience
Some of these sort of descend into each other, but generally, what this means is that the best way to remember something is to give it your full attention; try to remember something that is extremely arousing (not the sexin’ kind of arousing [necessarily]); and try to remember something that is relevant to you somehow.
But arousal and attention can sometimes be effectively the same thing; also, salience doesn’t really have to mean personal salience—something can also be salient because it’s new, because it’s dangerous, because it’s different from what you expected, because it differs sharply from the other things you’re attending to, etc. So these things are all pretty well interrelated.
So what does this have to do with vision? If you’re trying to encode a visual stimulus into your memory, you better have your eyes open, and you better attend to it fully. But if you’re trying to remember an auditory stimulus, you may do better to close your eyes and devote your full attention to the sound.
….I think. If I get a chance, I will ask in class today.