Take the 2-minute tour ×
Cognitive Sciences Stack Exchange is a question and answer site for practitioners, researchers, and students in cognitive science, psychology, neuroscience, and psychiatry. It's 100% free, no registration required.

I am currently programming an experiment where participants have to do a divided visual field task. In a paper about the correct methodology about these tasks, it is said that you should use a backward mask (a mask after the target) in order to avoid after-images.

I have no objection of inserting backward masks in my experiment, but I just can't find any rules about how to implement these correctly.

Does it matter if I use a random black/white pixel rectangle where the target was or some symbols (e.g., ### is often used in psycholinguistic experiments) on that location? Or should I put random black/white pixels over the whole screen?

(Location of the target/mask is not important for the participants, so a target-located or a full-screen mask does not change to the goal of my research.)

share|improve this question
1  
    
Interesting question. I was testing an iPhone app for "memory improvement" - repeat the yellow circle pattern seen on the screen. After each pattern it flashed all dots with green color. Your question makes me understand why the author did that. –  Alex Stone Apr 18 '13 at 2:22
add comment

Know someone who can answer? Share a link to this question via email, Google+, Twitter, or Facebook.

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.