Scientists made ape-centric horror movies to test how our primate cousins react to bone-chilling scenes. As it turns out, they react the same way we do.
Japan’s film industry is notorious for its hair-raising horror genre. Perhaps inspired by their national cinema, primate researchers from Kyoto University decided to use horror movies to test the long-term memory of chimps and bonobos. Previous studies have already established that apes can remember where a scientist hides food, but the Japanese scientists wanted to try something a little less mundane.
Fumihiro Kano and Satoshi Hirata had observed that apes show little interest in typical dramas, but any movies that depict violence catch their attention immediately. So they realized that horror movies might present the perfect way to test how apes access memories of single events. The researchers made two short films that they hoped would have a lasting effect on the apes’ memories. The first film showed human caretakers mimicking the apes’ typical behavior, clutching bananas as they crouched on the ground, until a man dressed in an ape suit suddenly bursts out of a door and attacks them. The second film showed the monster attacking again, but this time the human retaliates with a toy hammer.
Credit: Fumihiro Kano, and Kumamoto Sanctuary, Wildlife Research Center, Kyoto University
They showed each movie twice to a group of six chimps and six bonobos, using eye-tracking technology to observe which parts of the scene the apes focused on. Needless to say, the apes were completely riveted. But intriguingly, the second time the apes watched the films 24 hours later, they kept their eyes fixated on that door even before the monstrous ape-imposter appeared. While watching the second film, the apes also eyed the weapon that the human would use. Not only did the apes remember where and when to expect the attack, but they also expressed agitation by grimacing and vocalizing. They were able to store memories of what they’d seen, and then anticipate the attack before it happened a second time.
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The researchers believe that this type of long-term memory could help apes be prepared for dangerous situations in the wild, or complex social circumstances. It’s the first time they have been able to prove that apes store memories unrelated to food, and that a large portion of their cognition involves past and future events.
This experiment was possible thanks to Kano’s state-of-the-art monitoring technology. These devices are much smaller and easier to use than previous forms of equipment, and can track the apes’ eye movements more precisely. Kano hopes to use the technology, along with his newfound skills in ape-catered filmography, to answer other questions about ape cognition — for example, whether they can perceive the beliefs or intentions of others. This research could even kickstart a whole new genre of ape cinema.