How Visually Change Blind Are You?

Found an interesting cognitive neuroscience demonstration on Go Cognitive designed to let you test yourself in the change-blindness paradigm.  Change blindness involves making significant changes in a visual scene that go unnoticed.

The demo is fun, gives you a number of scenes to work with and lets you control some key parameters. Experiment a bit, especially with the strategy you use to detect changes. Try defocussing your eyes and looking at the images globally to detect a difference and then try systematically comparing the images item by item. Which gives you a better score?