The close reflex is triggerd when similar parts of the brain react to an image on a computer screen, like the throat does when fingers or penis are forced into the mouth. Making it related to the gag reflex.
Mark is browsing the internet, when his friend John sends him a link on msn to website called <Insert disgusting shock image website here>. Upon the webpage loading, he instantly looksaway in disgust, and his close reflex kicks in. His hand quickly moves up and to the right and clicks. Causing the web page to be closed within seconds.