So I guess my question is, when I don't see anything except black, or gray, no streaks, no spots, no points of light, and only the slightest bit of movement from one frame to the next, what is going on there? Why is it completely black?
That is simply volume that doesn't contain any blood vessels! The bits of movement could be autofluorescence from other tissues that aren't stained with the dye, but if a volume (a few frames) remains black it's just that there was no dye in that area, indicating no vessels/ associated plasma.
Also, sometimes I'll see something that looks like a stall, but as I move the slider, a large amount of florescence seems to pass through the vessel, yet the expert still scores the vessel as being stalled even though florescence definitely passes through the vessel later in the movie. I always associate florescence with flowing plasma, but sometimes a large amount of florescence doesn't always indicate a flowing blood vessel. Why does the florescence become so very strong at some points even though the blood vessel is stalled?
To quote Nozomi, "The red blood cells are black gaps in the dye because the dye flows around the cells. As you have seen, there are also bright spots, sometimes quite large, through out the tissue. This is because there are some naturally occurring molecules that are also quite fluorescent. Some of these are associated with aggregates of proteins the appear in aging and in injury. To be honest, we don't know exactly what are those molecules. So when there is no dye injection, you can still see occasional dots and "splats" of brightness." So perhaps the expert is able to discern these artifacts by size, brightness, texture etc. noting that the bright white doesn't quite look like the flowing plasma we see in our unstalled vessels (one of the reasons automation of this process is so difficult actually)
Maybe @pietro could share some thoughts on the rest? Thanks for the great questions Mike
As I said in the original question, I believe that in the Eye Wire game, they display a three dimensional image of the cross-section along with a two dimensional image of the area that is being traversed. If there is some way that we could have a three dimensional image of the blood vessel in the stall catcher game, that would make it much more clear as to what is actually going on, although I'm not so sure how much it would help in identifying stalls.
One other thought occurred to me. Why does each movie not have a number, or a code associated with it? If each movie had a number associated with it, then if someone has a question about a movie, he or she could just refer to the number of the movie, and you would know which movie is being asked about. I assume that each movie must have some kind of a number, or code associated with it because otherwise you would have a really difficult time keeping them all straight, and organized, and you need to have some way of referring to them. On the other hand, the thought did occur to me that you can't really show the numbers associated with the movies because if you did, that would be too much of a memory aid for the participants, allowing them to definitely remember whether or not they saw a movie before, and that could lead to presentation effects. However, it would still be nice if there were some way for players to be able to refer to the movies if they have questions about them.