Bates says you should remember a perfectly black period. what im wondering is, should you actually find a perfectly black period somewhere and remeber what it looks like? like, for example, would a period in a book be ok to use? and also is it ok to imagine a perfectly white background behind the period? and should you imagine the period moving around instead of static an still since that would be like mentally staring?
This seems to be really more of a personal, "what works for you" thing, but here are my opinions on what you said.
I always find it easier to imagine something I've just seen earlier, I think thats why Bates liked to give a second snellen to his patients for them to hold and view close up, enabling them to better remember exactly what it looked like, fresh in their memory. Its also ok to imagine a perfectly white background behind it, but I think that the background should be of secondary or no concern. Maybe it might make it easier to call forth the dot if you aren't concerned with a background as well? either way I think whatever way makes it easiest for you.
I've heard of many people swinging the dot in their imagination. IE, the imagine the dot as they close their eyes and swing their body, imagining the dot swinging back and forth across their vision.
I can't remember though, didn't Bates go into pretty good detail on this?
