There are currently two kinds of manipulations. One blurs the image outside the magic window, and the other makes the areas outside the circle dim. Choose one of the links below to try them out.
If the applet doesn't load for you, you may not have java installed on your own computer. You can download java from:
java.sun.com (download the J2SE 5.0 JRE version)
You can also download the double-clickable application with all the image files: Change Blindness Application (zip file) To use this, right-click on the link and then save it to your desktop. Find the file and then right-click on it to unzip it. Then find the .zip file and uncompress it by clicking on it. Finally, find the ChangeBlindness.jar file and double-click on it to run the program.
To see a movie that describes how to use the application, using this link: Introductory Movie for Application
Here are some articles on Change Blindness: Link to Articles