System requirements

Q: What kind of computer or mobile device do I need to play Stall Catchers?

A: Stall Catchers is designed to work on an Internet-connected computer running any modern operating system and internet browser with JavaScript enabled.

Q: Do I have to install any software?

A: Nope. Stall Catchers does not require the installation of any special software. It just runs on your Web browser.

Q: Do I need a fast Internet connection to play this?

A: It depends on how patient you are ;) The faster your connection, the less time you will have to wait for each vessel movie to load. With a normal Internet connection, you might not notice any delays at all (and we load the next movie in the background to help). But with a very slow internet connection (~40 kbps) it could take up to 90 seconds for each movie to load. (Each movie is about a 0.5 Mb download).


Q. What is the grand goal of Stall Catchers?

A. To find a treatment for Alzheimer's disease. Researchers at Cornell University have discovered a number of important clues on understanding, preventing and reversing Alzheimer's in mice. But we must answer some key questions before we will be able to find a treatment for humans. We need your help to answer them as fast as possible.

Q. How long will Stall Catchers go on?

A: As long as there are unanswered questions concerning reduced blood flow in the brain that we need to answer to find a promising treatment target. It doesn't look like we'll be running out of research questions to analyze any time soon!

Q: Do I need to be a scientist to contribute to Stall Catchers?

A: Not at all! Anyone can contribute by watching vessel movies and searching for signs of stalls.

Q: Is there an age limit to participate?

A: Nope!

Q: I have doubts about my ability to annotate movies correctly. Can I still participate?

A: Absolutely! Your answers will be combined with those of other participants to produce a “crowd” answer, so you have no reason to worry about getting each answer right. Just give the best answer you can, and have fun!

Q: What do I need to play the game? Does Stall Catchers download anything to my device?

A: All you need is a browser and an internet connection. The game does not require installation of any software.

Q: Why can't scientists do this themselves?

A: Even though scientists at Cornell University have powerful tools to acquire Alzheimer’s research data, the analysis step is so time consuming that it would take decades for a small group of researchers to analyze the data on their own. By playing this game, we could speed up the research by orders of magnitude!

Q: How do I start?

A: View the tutorial video (under “Tutorial”) and, if you feel you need a more in-depth instruction, you can read the written description of “Finding Stalls” on the same page. Then go ahead and Register! You’ll be taken straight to the game after you click on the email confirmation.

Q: Why do I have to register to play the game?

A: In order to produce valid scientific results we have to keep participant answers separate from each other. This also allows us to update your personalized dashboard with your online accomplishments.

Q: I continue to get a message "wrong reCAPTCHA" while registering. What do I do?

A: If you are sure your input is correct, and you have tried several times without luck, it is possible that reCAPTCHA is not working at the moment. reCAPTCHA is an external service that might go offline for reasons beyond our control. Do try again in a few minutes or a few hours at most! Please Email us at info@eyesonalz.com if the problem persists.

Q: I registered on Stall Catchers but I am having trouble logging in. What do I do?

A: First, make sure that you are logging in with the same email address you used to register and that it is typed correctly. If you think you might have forgotten your password, click on the “Forgot password” link and follow the instructions in the password reset email you receive.

Note that if you used Facebook or Google+ to register, you need to follow the respective Facebook/Google+ links on the login page as well (typing your email address & password will not work).

If you are still having trouble logging in, please email us at info@eyesonalz.com and we will resolve it for you!

Q: How do I change my password?

A: Click the login link at the top of the page and then click the “Forgot password” link. You will receive a password reset email. Just follow the instructions in the email to create a new password.

Q: What is EyesOnALZ, and what does it have to do with Stall Catchers?

A: EyesOnALZ is a citizen science project run by the Human Computation Institute, and supported by the BrightFocus Foundation. EyesOnALZ team includes collaborators from The Schaffer-Nishimura Lab at Cornell University, The Space Science Laboratory at U.C. Berkeley, Sebastian Seung’s Laboratory at Princeton University, WiredDifferently, and SciStarter.

Q: Where do I find more information about the game and the project?

A: Check the “About” section on this site, visit the EyesOnALZ project page, and follow our Blog! You can also find us on SciStarter.com.

Q: Where can I get support and report any problems?

A: You can get further support by reporting issues via email - info@eyesonalz.com, or posting on the relevant sections on our Forum. Don’t forget to check the existing threads to make sure nobody else has reported the same issues! We do not provide telephone support, but our active forum will provide quick answers.

Vessel movies

Q: What is the Virtual Microscope?

A: The Virtual Microscope (VM) is a special tool developed by stardust@home citizen science project team. The VM downloads vessel movies from the database and allows you to look into real movies of mouse brain vessels via your web browser.

Q: Where are the vessel movies coming from?

A: Researchers at Cornell University, Schaffer – Nishimura Lab are using two-photon microscopes to look into live mouse brain and acquire high-resolution vessel images. These are then processed to produce vessel movies, and fed into our system for you to annotate!

Q: Have any of the movies been annotated by experts?

A: Some of them. We call these “calibration movies”. They have been fully annotated by researchers at Cornell University (so we know which of them are flowing and stalled). Answering calibration movies right or wrong determines your score. The vast majority of movies, however, have not been seen by experts yet. We call these “real” movies. Real movies are entirely up to the Crowd to annotate!

Q: How many vessel movies are there in the game?

A: We are starting with several thousand vessel movies, but we will add new movies all the time from the Schaffer–Nishimura Lab!

Q: What are “layers” in the vessel movies? What is “layer number”?

A: “Layers” correspond to individual frames in the vessel movies, each corresponding to a layer of brain tissue at a different depth. Therefore, as you scroll through the movie, you are looking at deeper and deeper layers of the brain tissue and the vessel. “Layer number” indicates which layer you are looking at. This is especially useful to track the beginning and the end of the movie while Autoscrolling. It is also useful when commenting on a vessel to let other people know which layer(s) might be relevant to your comments.

Q: What to do if a movie is particularly unclear?

A: Some movies may be out of focus, have misaligned frames or “bad outlines”: outlines that are missing, do not align with a vessel, or jump to a new spot in the same movie. These movies occasionally result as a side-effect of the pre-processing of the vessel movies.

In all cases, always do your best to give an answer, even if a movie is unclear! If it is particularly problematic, simply tick the “Flag movie” box, record your best guess & move on. We will look at all flagged movies & resolve or remove them from Stall Catchers.

Q: What happens to broken vessel outlines?

A: It usually takes less time for an expert to just look at a bad outline and make a final determination about the vessel (whether it is flowing or stalled). So in most cases, bad outlines will not be fixed. Instead, the expert will simply remove the movie from Stall Catchers and, if there is indeed a vessel in the outline, annotate it her/himself.

Q: Can I increase the size of the vessel movies to see them better?

A: At the moment there is no in-game feature to increase the movie size (they are at their maximum resolution), but you can always try zooming a bit in your browser (Control + Plus sign usually works, or Command + Plus sign on Mac). Also see below for tips on changing contrast to see movies better.

Q: Can I change the contrast/brightness of the vessel movies to see them better?

A: There is no in-game feature to change these parameters for the movies, but you could also try changing the contrast of your screen itself to make the movies stand out a little better. A more long-term solution could be inverting the colors in your browser for the Stall Catchers window. Most browsers have plugins for that, e.g. "Invert Colors" on Firefox, "Invert Page Colors" on Chrome etc.

Finding Stalls

Q: How can I tell if a vessel is stalled?

A: If you see at least one dark spot in the vessel that doesn't move, then it is probably stalled. Check also the “Tutorial” section for more tips and examples.

Q: Where can I find more examples of stalled and flowing vessels?

A: The “Tutorial” section contains more examples of stalled and flowing vessels, and tips about annotating movies.

Q: How many vessels am I annotating in each movie?

A: One. Each movie should contain a single vessel segment enclosed within a green outline and following the shape of the outline. If you think the area contains more than one vessel, you can notify us via the Forum. Sometimes more than one vessel appears within an outlined area. When this happens, the vessel you should be annotating is the one that most closely follows the shape of the outline.

Q: Where can I review the tutorial video?

A: Under “Tutorial” tab at the top panel. You can view the tutorial as many times as you like, and there is an in-depth written tutorial there too!


Q: How is my score determined?

A: Your score is roughly a function of the vessel difficulty and your proven ability to detect stalls.

Q: Can my score go down?

A: Your score will never go down :)

Q: What does "level" mean?

A: Level indicates how experienced you are as a stall catcher. Each time your score gets high enough, you go up another level. It takes more points to get promoted at higher levels than at lower levels.

Q: What does "next" indicate?

A: This tells you how high your score needs to get to advance to the next level

Q: How is my rank determined?

A: Your rank is based on your score relative to other participants. The best possible rank is 1. The lowest possible rank depends on the number of participants.

Q: What does the "movies" statistic refer to?

A: The number of vessel movies you have annotated since you became a Stall Catcher

Q: What does the "stalls" number mean?

A: This indicates the number of stalls you have correctly identified as verified by an expert.

Q: What does sensitivity mean?

A: Your sensitivity indicates your ability to distinguish between flowing and stalled vessels. When your sensitivity is higher, you will get more points for each correct annotation. Your more recent activity has a greater impact on this number than your past performance. In general, your sensitivity will fluctuate depending on how alert you are on a given day, and may increase as you become more experienced.

Q: What does the layer number represent?

A: This indicates which layer of brain tissue you are looking at at any given moment. When you move the slider back and forth to watch the vessel movie, you are not only moving backward and forward in time, but also moving upward and downward through layers of brain tissue. These layers are numbered such that layer 1 is at the top of the stack.

Q: What does the "autoscroll" checkbox do?

A: When "autoscroll" is checked, the vessel movies will play automatically and repeatedly so you don't have to use the slider.

Q: What does the "show answer" checkbox do?

A: When "show answer" is checked, each time you give an answer, you will see feedback about how your answer compares to answers from experts or other stall catchers.

Q: What does the "flag movie" checkbox do?

A: When you check the "flag movie" checkbox, that lets our experts know there is something wrong with the vessel movie. Please do not use this box to indicate that the movie is too difficult. It should be used to flag a technical issue; for example, to indicate that the movie did not load properly. It lets us know that we need to look into something related to that movie.

Q: What does a “Maybe!” answer mean? Why is it “up to the Crowd”?

A: Since vessel data analysis is so time-consuming, experts cannot analyze all the movies by themselves. That‘s why some movies in Stall Catchers have not been answered by experts. We call them “real” movies, and we cannot tell you whether you answered correctly, i.e. whether they are flowing or stalled.

This is where the Crowd comes in. We will use the crowd consensus to determine the flowing/status of the movie, when it has been answered by multiple stall catchers! You get points for your contribution in any case!

Q: What does a "flag feedback" mean?

A: Check this box if the Expert feedback seems wrong or confusing, or if there is inappropriate community feedback.

Q: I continue to get a message "wrong reCAPTCHA" while registering. What do I do?

A: If you are sure your input is correct, and you have tried several times without luck, it is possible that reCAPTCHA is not working at the moment. reCAPTCHA is an external service that might come offline for a reason beyond our control. Do try again in a few minutes or a few hours at most! Email us at info@eyesonalz.com if the problem persists.

Q: Redeem button. What do the messages “No points yet” and “Redeem points!” mean?

A: The redeem button allows you to claim back the points you earned for the real movies answered correctly. Since real movies have not been seen by experts, we rely on the crowd to determine whether they are flowing or stalled. When you annotate a real movie you will most often get a “Maybe!” answer, and a few points as a reward. However, as soon as we accumulate enough crowd annotations to know the answer for certain, you will be able to redeem the full points you earned, if you answered the movie correctly. Click on the Redeem button when the message changes to "Redeem points!" to get the full points you earned for redeemable real movies (the amount per movie will compare to that earned for calibration movies). After you have redeemed your points the message will change back to "No points yet", until at least one more of your annotated real movies becomes available to redeem again. If you click on the “No points yet” message, you will be able to see how many movies are in the queue to be redeemed, e.g. "5 movies pending".

Teams and Leagues

Q: What is a “team” in Stall Catchers? Who can create a team?

A: A team is absolutely any group of Stall Catchers players, who choose to pool their scores together and compete with other teams or with each other within a team. Anyone can form a team, although note that you can only belong to one team at a time, so if you create a new team, your membership in the former team will be lost (though you can always rejoin later).

Q: What is “Team Humanity”?

A: Team Humanity is the team which all Stall Catchers belong to - aren’t we all in this for humanity’s sake? Team Humanity does not compete with other teams, and represents the pooled achievements of all players.

Q: How many teams can I contribute to? Will my points be saved when I switch teams?

A: You can contribute to only one team at a time, which is why if you join or create another team, your active membership in the former team will be lost. However, the original team will still retain all the points you contributed, and you can start where you left off if you ever go back. In the meantime, you will have to start contributing points to the new team from scratch. Your individual all-time score will not be affected.

Q: How do I create a team?

A: Navigate to the “Teams” menu and click on “Create a new team”. Fill in a short team registration form, upload a logo, click “Create” and you’re done!

Q: How do I join a team?

A: Navigate to the “Teams” menu, browse the available teams (if you click on their titles you will be taken to their full page), and click “Join” next to the one you like.

Q: How do I leave a team?

A: Navigate to the “Teams” menu & select another team you like to leave your current team. You can also click on the “Leave” button next to your current team name to leave it without selecting a new one. You’ll still belong to Team Humanity though - we all do!

Q: How do I invite new members to join my team?

A: In your team page you can copy & share the link that will lead new Stall Catchers players to register and then automatically join your team. Players who have already registered will be invited to join your team. Otherwise, you can advertise your team (and lure the best players from other teams!) in the EyesOnALZ forum.

Q: What is a “league”? Who can create a league?

A: A league is a group of teams united under one topic, agenda, level or goal - whatever you can think of. E.g., “Fourth graders” league might be formed by multiple 4th grade classrooms that each form a separate team in Stall Catchers, and compete with each other within the league. Anyone can create a league.

Q: How many leagues can one team be a part of?

A: Only one. Any team can choose to compete in one league, and can change it at any time.

Q: How does a team join a league?

A: Only team owners can do this. Navigate to your Team page and click “Edit team”. You will see a dropdown menu for “League” - select the one you want and click “Save”.

Q: How does a team leave the league?

A: Only team owners can do this. Navigate to your Team page and click “Edit team”. You will see a dropdown menu for “League” - select “No league” and click “Save”.

Q: What is the Team score?

A: The Team score is the sum of points of all its former and current members, contributed while part of that team. The individual scores of a player are added to the team score only as long as that player is a member of the team. Once they leave the team, their newly gained points are no longer added to the team score, but the team retains all the points that the player contributed during the period of membership.

Q: What is League rank?

A: League rank is the position of a team in the leaderboard relative to other teams that are part of the same League.

Q: What is Overall team rank?

A: Overall team rank is the position of a team in the overall team leaderboard. This compares all teams to each other regardless of league membership.

Q: What are "Today/This week/All time" team leaderboards?

A: Today/This week/All time team leaderboards on the virtual microscope & the leaderboard pages list teams that are in the lead during the specified time periods. The daily leaderboards reset at 0:00 EST every day, weekly - 0:00 EST every Sunday.