Below are links to seven sample demonstrations of 1 item with a 600 ms mask.
Three file formats are available for viewing:
After selecting a demonstration, fixate on the cross. A single shape (square, circle, triangle, or diamond) will appear. This shape will be surrounded by four dots. Your task is to identify the shape within the four dots. Animated GIF files have a compact file size. You must have javascript-enabled browser to view them. AVI files (Windows) are of a higher quality with greater temporal precision; however, AVI files take longer to download because of their size. Selecting a demo should automatically launch your browser's media player. Ensure that the media player is not set to loop the movie. QuickTime movies are viewable on either Mac or Windows platforms. You must have the QuickTime player to view them. Download Quicktime.
In this situation, most people can see the shape inside the four dots. This is because the single target can be found quickly and attended selectively. Object Substitution occurs only with unattended targets.