When Japanese researchers wanted to see if chimps could learn things from simply viewing a situation just once, they needed to create situations where apes would anticipate a noteworthy event. So they made their own horror films just for apes.
The plots of King Kong Attack and Revenge of King Kong were rudimentary. There was only one set -- a room with two doors, a couple of researchers form Kyoto University, and a few scattered objects. In King Kong Attack, one of the doors opened and a man in an ape suit came barreling through. He made a few threatening motions before the film ended. In Revenge of King Kong, one of the researchers in the room fought back against King Kong, using a specific object.
It probably would have rated very low on the Rotten Tomato Meter if its sole audience weren't chimpanzees and bonobos. The chimps watched the film while they were being monitored by eye-tracking software.
A day later, the chimps watched the film again. Clearly it had some kind of impact. While rewatching King Kong Attack, the chimps steadily looked at the door through which King Kong had entered, and ignored the door through which they didn't expect an attacker. When they watched Revenge of King Kong, they focused on the object that the researcher had used to do battle with the rampaging ape, even if the object was in a different place on the screen.
The researchers write that these results show that, "great apes, just by watching the events once, encoded particular information (location and content) into long-term memory and later retrieved that information at a particular time in anticipation of the impending events."
The apes, meanwhile, look forward to the DVD release, and have commented positively on the films' reliance on practical effects rather than that "CGI crap."