Using eye-tracking technology, researchers showing specially made movies to chimps and bonobos discovered that the apes not only recall scenes that they’ve watched just once before, but they can also anticipate action sequences. Their work, published in Current Biology this week, suggests that apes encode information about events into their long-term memories and use them later to prepare for things that are about to happen.
"When you watch a shocking, emotional event in a movie, you remember the event well, and later on, when you watch the same movie, you anticipate the event," Kyoto University’s Fumihiro Kano explained in a statement. “Thanks to a recent advance of state-of-the-art eye-tracking technologies, we could examine event anticipation by great apes while watching a movie by means of 'anticipatory looks' to the impending events."
Great apes are known to have excellent memory skills, but previous studies focused mostly on retrieving food. But like humans, apes seem to remember emotional events rather than neutral ones. So, Kano’s team created and starred in two 30-second films with emotionally charged scenes depicting dramatic acts of aggression committed by a researcher dressed in a King Kong costume. In one video, the ape impersonator burst in through a door, and in the other, the fake ape attacked a person who then retaliated using a toy weapon. (You can watch the videos below.)
They then showed the short movies to six chimpanzees and six bonobos on two consecutive days while tracking their eye movements to see if the apes noticed and remembered the major plot points. On the second viewing, the apes looked at the doorway 3 seconds before the fake ape showed up and also at the weapons that were later used against the phony ape. In fact, for the second showing, the weapons were placed in different locations, yet the apes still looked at the object and not its former spot.
“The fact they remembered such details from the previous video was really impressive,” Kano told New Scientist. Being able to anticipate and avoid impending danger or remember what other apes did to negotiate social environments might be important for survival. Not to mention, the chimps and bonobos seemed to enjoy watching the movies too. "We were giving juice while showing the videos to them," Kano adds, "but some of them even forgot to drink [the] juice and stared at the movies!"