A new paper, co-authored by Ph.D. student Noam Josef and Dr. Nadav Shashar of Ben Gurion University’s Department of Life Sciences, suggests that octopi focus on a limited selection of nearby objects in order to determine their disguise. The youtube video is remarkable.
http://blogs.scientificamerican.com/octopus-chronicles/2012/06/01/how-octopuses-make-themselves-invisible/
http://www.youtube.com/watch?v=JJq-wAUmkeg&feature=player_embedded