I always remember the correct answer for this movie, but I don't understand it

After being shown this movie over and over again, I have learned to mark the vessel as stalled. I always remember now that the vessel is stalled, but I still don’t understand it. The luminescence passes right through the vessel, so why is it considered to be stalled?

What I think happens in this movie, if I’m remembering the right one, is that there are two vessels. The stalled vessel is the thinner fainter one, then there is a different really bright one. The next time this movie comes up for me I will take some screenshots to try to explain it better.

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Mike, I think the key is, as you stated, that the "luminescence passes right through … " There are a few movies like that, I believe. If you focus on the gap (stall), it is stationary, but sometimes the fluorescence washes out the view so you might think it has ‘moved on’ when it really has not. I think I missed this one early on as well.
Mike C.

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Okay, thanks! I guess what confuses me is that recently they added the criterion that the stall has to be present for the entire movie in order for the blood vessel to be considered as stalled. I guess what they mean by that is that the stall has to be visible for the entire movie. Well, here is a case where the stall is only visible immediately before it gets washed out by the luminescence. If the stall has been washed out by the luminescence, how do we know that it is still present?

For me, the assumption here is that the stall is still present even though it’s not visible to the eye. I don’t understand how we can know this just based upon what is visible. The expert knows based on some information, or knowledge that the stall is still there, but how are we supposed to know that? It just seems to me that this is one occasion, and I do believe there are many others, when the expert makes a determination based on something other than what is visible to the eye.

Hi Mike,

I have been playing for awhile and haven’t come across this movie, but I wanted to make a comment. I take the criterion that the stall should be present for the entire movie to mean that the stall should be present the entire time the target vessel is present. I think the experts should clarify this because there are very few movies where the stall is visible in every single frame and I think it is confusing to users.

Something else to keep in mind is that as you move through the movie you are moving both through time and through space in the z direction. Think of each frame as a page in a book, as you read through the book you are moving through time as well as physically moving to another page. So when you say the “luminescence passes right through” it is actually a different bright vessel passing above (or below depending on how they have ordered the slices) the target vessel.

I’ll still keep my eye out for this movie as well as the other one you asked about as I play.

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Okay thanks for the reply! I wish they could include some type of three-dimensional cross-sectional representation in the interface. It would really clarify what we are looking at when we look at these movies. I always forget about the three dimensional aspect of the percept because we don’t see that the third dimension. We are experiencing a three dimensional phenomenon in a two dimensional plane, and I guess that kind of compresses everything together which makes things all the more confusing. Actually, when you think about it it’s actually a four dimensional experience because time is the fourth dimension.

Hi Mike -
I did finally run into this one. Here is the vessel displayed from frame 18 to frame 36 (every other frame). You can see that the dark spot does remain stationary while the vessel is visible. As GnabGib said, you should only be considering the visibility of the stall while the targeted vessel is visible. This vessel gets obscured by another vessel as the movie progresses. Before frame 18 and after frame 36, the targeted vessel is really not visible enough to detect anything else. Cheers.

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Thanks gcalkins for posting those images, that movie still hasn’t popped up for me.

I just wanted to say that I agree with Mike that it would nice to have a 3D representation to help users visualize what is happening. I don’t think it would be feasible or all that helpful to have it for every movie, but maybe somewhere in the introduction or tutorials. It would be nice to see a few examples of the actual data in 3D rather than computer generated animations of blood vessels. I’ve made a couple quick examples of a flowing vessel and a stalled vessel. I’m sure the developers of this site could make some nicer ones than these.


Those 3D images look great! It would be really good if they could put a slider on the image like the one we have in the game, so the image could be rotated manually by the user. Do you think they could do something like that? Thanks for making the videos!

Thanks for the explanation! I still don’t see the dark spot in all of the frames, but I do see it much more clearly in these screenshots than I do on my computer screen when I’m playing the game. What type of software did you use to make these screenshots? I don’t currently have the capability to make screenshots as clear as these are. Your equipment is better than what I have. I guess the resolution would also vary based upon what type of equipment is being used to view the movies. Do you have the ability to magnify the images?

Glad I could help. I’m not sure if it would be feasible to add 3D functionality to every movie. It would mean the app would have to load at least twice as much data and that might make loading too slow for some users. I find that sometimes the movies already load so slow that I stop playing for awhile and I have a decent internet connection. But I’m not a programmer so it would be a question for one of the developers.

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When you use the slider the dark spot is a little more obvious and is quite stationary.

I am using a laptop PC. Trying to use a tablet or other handheld device would be quite difficult to have adequate resolution without some sort of zooming capability. That would be where using the “autoscroll” may come in useful. I personally find the slider more useful and my default screen resolution is adequate, but in order to zoom or use a magnifier it may be necessary to use the autoscroll.

I use the Windows “Snipping Tool” to capture images, which is available with all Windows operating systems. It is in with all of the other Windows accessories. It allows you to capture just what you want on the screen and then save it directly to a JPG image file.